alpha: Use new generic strncpy_from_user() and strnlen_user()
Similar to x86/sparc/powerpc implementations except: 1) we implement an extremely efficient has_zero()/find_zero() sequence with both prep_zero_mask() and create_zero_mask() no-operations. 2) Our output from prep_zero_mask() differs in that only the lowest eight bits are used to represent the zero bytes nevertheless it can be safely ORed with other similar masks from prep_zero_mask() and forms input to create_zero_mask(), the two fundamental properties prep_zero_mask() must satisfy. Tests on EV67 and EV68 CPUs revealed that the generic code is essentially as fast (to within 0.5% of CPU cycles) of the old Alpha specific code for large quadword-aligned strings, despite the 30% extra CPU instructions executed. In contrast, the generic code for unaligned strings is substantially slower (by more than a factor of 3) than the old Alpha specific code. Signed-off-by: Michael Cree <mcree@orcon.net.nz> Acked-by: Matt Turner <mattst88@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Michael Cree
Linus Torvalds
parent
d8d5da1298
commit
f2db633d30
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@ -18,6 +18,8 @@ config ALPHA
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select ARCH_HAVE_NMI_SAFE_CMPXCHG
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select GENERIC_SMP_IDLE_THREAD
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select GENERIC_CMOS_UPDATE
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select GENERIC_STRNCPY_FROM_USER
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select GENERIC_STRNLEN_USER
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help
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The Alpha is a 64-bit general-purpose processor designed and
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marketed by the Digital Equipment Corporation of blessed memory,
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@ -433,36 +433,12 @@ clear_user(void __user *to, long len)
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#undef __module_address
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#undef __module_call
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/* Returns: -EFAULT if exception before terminator, N if the entire
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buffer filled, else strlen. */
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#define user_addr_max() \
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(segment_eq(get_fs(), USER_DS) ? TASK_SIZE : ~0UL)
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extern long __strncpy_from_user(char *__to, const char __user *__from, long __to_len);
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extern inline long
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strncpy_from_user(char *to, const char __user *from, long n)
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{
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long ret = -EFAULT;
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if (__access_ok((unsigned long)from, 0, get_fs()))
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ret = __strncpy_from_user(to, from, n);
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return ret;
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}
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/* Returns: 0 if bad, string length+1 (memory size) of string if ok */
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extern long __strlen_user(const char __user *);
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extern inline long strlen_user(const char __user *str)
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{
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return access_ok(VERIFY_READ,str,0) ? __strlen_user(str) : 0;
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}
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/* Returns: 0 if exception before NUL or reaching the supplied limit (N),
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* a value greater than N if the limit would be exceeded, else strlen. */
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extern long __strnlen_user(const char __user *, long);
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extern inline long strnlen_user(const char __user *str, long n)
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{
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return access_ok(VERIFY_READ,str,0) ? __strnlen_user(str, n) : 0;
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}
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extern long strncpy_from_user(char *dest, const char __user *src, long count);
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extern __must_check long strlen_user(const char __user *str);
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extern __must_check long strnlen_user(const char __user *str, long n);
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/*
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* About the exception table:
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@ -0,0 +1,55 @@
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#ifndef _ASM_WORD_AT_A_TIME_H
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#define _ASM_WORD_AT_A_TIME_H
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#include <asm/compiler.h>
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/*
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* word-at-a-time interface for Alpha.
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*/
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/*
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* We do not use the word_at_a_time struct on Alpha, but it needs to be
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* implemented to humour the generic code.
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*/
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struct word_at_a_time {
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const unsigned long unused;
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};
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#define WORD_AT_A_TIME_CONSTANTS { 0 }
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/* Return nonzero if val has a zero */
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static inline unsigned long has_zero(unsigned long val, unsigned long *bits, const struct word_at_a_time *c)
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{
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unsigned long zero_locations = __kernel_cmpbge(0, val);
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*bits = zero_locations;
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return zero_locations;
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}
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static inline unsigned long prep_zero_mask(unsigned long val, unsigned long bits, const struct word_at_a_time *c)
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{
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return bits;
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}
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#define create_zero_mask(bits) (bits)
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static inline unsigned long find_zero(unsigned long bits)
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{
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#if defined(CONFIG_ALPHA_EV6) && defined(CONFIG_ALPHA_EV67)
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/* Simple if have CIX instructions */
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return __kernel_cttz(bits);
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#else
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unsigned long t1, t2, t3;
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/* Retain lowest set bit only */
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bits &= -bits;
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/* Binary search for lowest set bit */
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t1 = bits & 0xf0;
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t2 = bits & 0xcc;
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t3 = bits & 0xaa;
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if (t1) t1 = 4;
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if (t2) t2 = 2;
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if (t3) t3 = 1;
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return t1 + t2 + t3;
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#endif
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}
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#endif /* _ASM_WORD_AT_A_TIME_H */
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@ -74,8 +74,6 @@ EXPORT_SYMBOL(alpha_fp_emul);
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*/
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EXPORT_SYMBOL(__copy_user);
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EXPORT_SYMBOL(__do_clear_user);
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EXPORT_SYMBOL(__strncpy_from_user);
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EXPORT_SYMBOL(__strnlen_user);
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/*
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* SMP-specific symbols.
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@ -31,8 +31,6 @@ lib-y = __divqu.o __remqu.o __divlu.o __remlu.o \
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$(ev6-y)memchr.o \
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$(ev6-y)copy_user.o \
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$(ev6-y)clear_user.o \
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$(ev6-y)strncpy_from_user.o \
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$(ev67-y)strlen_user.o \
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$(ev6-y)csum_ipv6_magic.o \
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$(ev6-y)clear_page.o \
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$(ev6-y)copy_page.o \
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@ -1,424 +0,0 @@
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/*
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* arch/alpha/lib/ev6-strncpy_from_user.S
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* 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
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*
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* Just like strncpy except in the return value:
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*
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* -EFAULT if an exception occurs before the terminator is copied.
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* N if the buffer filled.
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*
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* Otherwise the length of the string is returned.
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*
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* Much of the information about 21264 scheduling/coding comes from:
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* Compiler Writer's Guide for the Alpha 21264
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* abbreviated as 'CWG' in other comments here
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* ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
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* Scheduling notation:
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* E - either cluster
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* U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
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* L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
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* A bunch of instructions got moved and temp registers were changed
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* to aid in scheduling. Control flow was also re-arranged to eliminate
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* branches, and to provide longer code sequences to enable better scheduling.
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* A total rewrite (using byte load/stores for start & tail sequences)
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* is desirable, but very difficult to do without a from-scratch rewrite.
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* Save that for the future.
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*/
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#include <asm/errno.h>
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#include <asm/regdef.h>
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/* Allow an exception for an insn; exit if we get one. */
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#define EX(x,y...) \
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99: x,##y; \
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.section __ex_table,"a"; \
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.long 99b - .; \
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lda $31, $exception-99b($0); \
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.previous
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.set noat
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.set noreorder
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.text
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.globl __strncpy_from_user
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.ent __strncpy_from_user
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.frame $30, 0, $26
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.prologue 0
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.align 4
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__strncpy_from_user:
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and a0, 7, t3 # E : find dest misalignment
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beq a2, $zerolength # U :
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/* Are source and destination co-aligned? */
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mov a0, v0 # E : save the string start
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xor a0, a1, t4 # E :
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EX( ldq_u t1, 0(a1) ) # L : Latency=3 load first quadword
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ldq_u t0, 0(a0) # L : load first (partial) aligned dest quadword
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addq a2, t3, a2 # E : bias count by dest misalignment
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subq a2, 1, a3 # E :
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addq zero, 1, t10 # E :
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and t4, 7, t4 # E : misalignment between the two
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and a3, 7, t6 # E : number of tail bytes
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sll t10, t6, t10 # E : t10 = bitmask of last count byte
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bne t4, $unaligned # U :
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lda t2, -1 # E : build a mask against false zero
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/*
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* We are co-aligned; take care of a partial first word.
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* On entry to this basic block:
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* t0 == the first destination word for masking back in
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* t1 == the first source word.
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*/
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srl a3, 3, a2 # E : a2 = loop counter = (count - 1)/8
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addq a1, 8, a1 # E :
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mskqh t2, a1, t2 # U : detection in the src word
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nop
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/* Create the 1st output word and detect 0's in the 1st input word. */
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mskqh t1, a1, t3 # U :
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mskql t0, a1, t0 # U : assemble the first output word
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ornot t1, t2, t2 # E :
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nop
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cmpbge zero, t2, t8 # E : bits set iff null found
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or t0, t3, t0 # E :
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beq a2, $a_eoc # U :
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bne t8, $a_eos # U : 2nd branch in a quad. Bad.
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/* On entry to this basic block:
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* t0 == a source quad not containing a null.
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* a0 - current aligned destination address
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* a1 - current aligned source address
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* a2 - count of quadwords to move.
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* NOTE: Loop improvement - unrolling this is going to be
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* a huge win, since we're going to stall otherwise.
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* Fix this later. For _really_ large copies, look
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* at using wh64 on a look-ahead basis. See the code
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* in clear_user.S and copy_user.S.
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* Presumably, since (a0) and (a1) do not overlap (by C definition)
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* Lots of nops here:
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* - Separate loads from stores
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* - Keep it to 1 branch/quadpack so the branch predictor
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* can train.
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*/
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$a_loop:
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stq_u t0, 0(a0) # L :
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addq a0, 8, a0 # E :
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nop
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subq a2, 1, a2 # E :
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EX( ldq_u t0, 0(a1) ) # L :
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addq a1, 8, a1 # E :
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cmpbge zero, t0, t8 # E : Stall 2 cycles on t0
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beq a2, $a_eoc # U :
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beq t8, $a_loop # U :
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nop
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nop
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nop
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/* Take care of the final (partial) word store. At this point
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* the end-of-count bit is set in t8 iff it applies.
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*
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* On entry to this basic block we have:
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* t0 == the source word containing the null
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* t8 == the cmpbge mask that found it.
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*/
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$a_eos:
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negq t8, t12 # E : find low bit set
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and t8, t12, t12 # E :
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/* We're doing a partial word store and so need to combine
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our source and original destination words. */
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ldq_u t1, 0(a0) # L :
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subq t12, 1, t6 # E :
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or t12, t6, t8 # E :
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zapnot t0, t8, t0 # U : clear src bytes > null
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zap t1, t8, t1 # U : clear dst bytes <= null
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or t0, t1, t0 # E :
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stq_u t0, 0(a0) # L :
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br $finish_up # L0 :
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nop
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nop
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/* Add the end-of-count bit to the eos detection bitmask. */
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.align 4
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$a_eoc:
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or t10, t8, t8
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br $a_eos
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nop
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nop
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/* The source and destination are not co-aligned. Align the destination
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and cope. We have to be very careful about not reading too much and
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causing a SEGV. */
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.align 4
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$u_head:
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/* We know just enough now to be able to assemble the first
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full source word. We can still find a zero at the end of it
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that prevents us from outputting the whole thing.
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On entry to this basic block:
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t0 == the first dest word, unmasked
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t1 == the shifted low bits of the first source word
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t6 == bytemask that is -1 in dest word bytes */
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EX( ldq_u t2, 8(a1) ) # L : load second src word
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addq a1, 8, a1 # E :
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mskql t0, a0, t0 # U : mask trailing garbage in dst
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extqh t2, a1, t4 # U :
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or t1, t4, t1 # E : first aligned src word complete
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mskqh t1, a0, t1 # U : mask leading garbage in src
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or t0, t1, t0 # E : first output word complete
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or t0, t6, t6 # E : mask original data for zero test
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cmpbge zero, t6, t8 # E :
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beq a2, $u_eocfin # U :
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bne t8, $u_final # U : bad news - 2nd branch in a quad
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lda t6, -1 # E : mask out the bits we have
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mskql t6, a1, t6 # U : already seen
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stq_u t0, 0(a0) # L : store first output word
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or t6, t2, t2 # E :
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cmpbge zero, t2, t8 # E : find nulls in second partial
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addq a0, 8, a0 # E :
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subq a2, 1, a2 # E :
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bne t8, $u_late_head_exit # U :
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nop
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/* Finally, we've got all the stupid leading edge cases taken care
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of and we can set up to enter the main loop. */
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extql t2, a1, t1 # U : position hi-bits of lo word
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EX( ldq_u t2, 8(a1) ) # L : read next high-order source word
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addq a1, 8, a1 # E :
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cmpbge zero, t2, t8 # E :
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beq a2, $u_eoc # U :
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bne t8, $u_eos # U :
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nop
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nop
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/* Unaligned copy main loop. In order to avoid reading too much,
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the loop is structured to detect zeros in aligned source words.
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This has, unfortunately, effectively pulled half of a loop
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iteration out into the head and half into the tail, but it does
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prevent nastiness from accumulating in the very thing we want
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to run as fast as possible.
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On entry to this basic block:
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t1 == the shifted high-order bits from the previous source word
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t2 == the unshifted current source word
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We further know that t2 does not contain a null terminator. */
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/*
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* Extra nops here:
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* separate load quads from store quads
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* only one branch/quad to permit predictor training
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*/
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.align 4
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$u_loop:
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extqh t2, a1, t0 # U : extract high bits for current word
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addq a1, 8, a1 # E :
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extql t2, a1, t3 # U : extract low bits for next time
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addq a0, 8, a0 # E :
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or t0, t1, t0 # E : current dst word now complete
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EX( ldq_u t2, 0(a1) ) # L : load high word for next time
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subq a2, 1, a2 # E :
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nop
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stq_u t0, -8(a0) # L : save the current word
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mov t3, t1 # E :
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cmpbge zero, t2, t8 # E : test new word for eos
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beq a2, $u_eoc # U :
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beq t8, $u_loop # U :
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nop
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nop
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nop
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/* We've found a zero somewhere in the source word we just read.
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If it resides in the lower half, we have one (probably partial)
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word to write out, and if it resides in the upper half, we
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have one full and one partial word left to write out.
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On entry to this basic block:
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t1 == the shifted high-order bits from the previous source word
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t2 == the unshifted current source word. */
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.align 4
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$u_eos:
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extqh t2, a1, t0 # U :
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or t0, t1, t0 # E : first (partial) source word complete
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cmpbge zero, t0, t8 # E : is the null in this first bit?
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nop
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bne t8, $u_final # U :
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stq_u t0, 0(a0) # L : the null was in the high-order bits
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addq a0, 8, a0 # E :
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subq a2, 1, a2 # E :
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.align 4
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$u_late_head_exit:
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extql t2, a1, t0 # U :
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cmpbge zero, t0, t8 # E :
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or t8, t10, t6 # E :
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cmoveq a2, t6, t8 # E :
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/* Take care of a final (probably partial) result word.
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On entry to this basic block:
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t0 == assembled source word
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t8 == cmpbge mask that found the null. */
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.align 4
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$u_final:
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negq t8, t6 # E : isolate low bit set
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and t6, t8, t12 # E :
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ldq_u t1, 0(a0) # L :
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subq t12, 1, t6 # E :
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or t6, t12, t8 # E :
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zapnot t0, t8, t0 # U : kill source bytes > null
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zap t1, t8, t1 # U : kill dest bytes <= null
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or t0, t1, t0 # E :
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stq_u t0, 0(a0) # E :
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br $finish_up # U :
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nop
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nop
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.align 4
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$u_eoc: # end-of-count
|
||||
extqh t2, a1, t0 # U :
|
||||
or t0, t1, t0 # E :
|
||||
cmpbge zero, t0, t8 # E :
|
||||
nop
|
||||
|
||||
.align 4
|
||||
$u_eocfin: # end-of-count, final word
|
||||
or t10, t8, t8 # E :
|
||||
br $u_final # U :
|
||||
nop
|
||||
nop
|
||||
|
||||
/* Unaligned copy entry point. */
|
||||
.align 4
|
||||
$unaligned:
|
||||
|
||||
srl a3, 3, a2 # U : a2 = loop counter = (count - 1)/8
|
||||
and a0, 7, t4 # E : find dest misalignment
|
||||
and a1, 7, t5 # E : find src misalignment
|
||||
mov zero, t0 # E :
|
||||
|
||||
/* Conditionally load the first destination word and a bytemask
|
||||
with 0xff indicating that the destination byte is sacrosanct. */
|
||||
|
||||
mov zero, t6 # E :
|
||||
beq t4, 1f # U :
|
||||
ldq_u t0, 0(a0) # L :
|
||||
lda t6, -1 # E :
|
||||
|
||||
mskql t6, a0, t6 # E :
|
||||
nop
|
||||
nop
|
||||
nop
|
||||
|
||||
.align 4
|
||||
1:
|
||||
subq a1, t4, a1 # E : sub dest misalignment from src addr
|
||||
/* If source misalignment is larger than dest misalignment, we need
|
||||
extra startup checks to avoid SEGV. */
|
||||
cmplt t4, t5, t12 # E :
|
||||
extql t1, a1, t1 # U : shift src into place
|
||||
lda t2, -1 # E : for creating masks later
|
||||
|
||||
beq t12, $u_head # U :
|
||||
mskqh t2, t5, t2 # U : begin src byte validity mask
|
||||
cmpbge zero, t1, t8 # E : is there a zero?
|
||||
nop
|
||||
|
||||
extql t2, a1, t2 # U :
|
||||
or t8, t10, t5 # E : test for end-of-count too
|
||||
cmpbge zero, t2, t3 # E :
|
||||
cmoveq a2, t5, t8 # E : Latency=2, extra map slot
|
||||
|
||||
nop # E : goes with cmov
|
||||
andnot t8, t3, t8 # E :
|
||||
beq t8, $u_head # U :
|
||||
nop
|
||||
|
||||
/* At this point we've found a zero in the first partial word of
|
||||
the source. We need to isolate the valid source data and mask
|
||||
it into the original destination data. (Incidentally, we know
|
||||
that we'll need at least one byte of that original dest word.) */
|
||||
|
||||
ldq_u t0, 0(a0) # L :
|
||||
negq t8, t6 # E : build bitmask of bytes <= zero
|
||||
mskqh t1, t4, t1 # U :
|
||||
and t6, t8, t12 # E :
|
||||
|
||||
subq t12, 1, t6 # E :
|
||||
or t6, t12, t8 # E :
|
||||
zapnot t2, t8, t2 # U : prepare source word; mirror changes
|
||||
zapnot t1, t8, t1 # U : to source validity mask
|
||||
|
||||
andnot t0, t2, t0 # E : zero place for source to reside
|
||||
or t0, t1, t0 # E : and put it there
|
||||
stq_u t0, 0(a0) # L :
|
||||
nop
|
||||
|
||||
.align 4
|
||||
$finish_up:
|
||||
zapnot t0, t12, t4 # U : was last byte written null?
|
||||
and t12, 0xf0, t3 # E : binary search for the address of the
|
||||
cmovne t4, 1, t4 # E : Latency=2, extra map slot
|
||||
nop # E : with cmovne
|
||||
|
||||
and t12, 0xcc, t2 # E : last byte written
|
||||
and t12, 0xaa, t1 # E :
|
||||
cmovne t3, 4, t3 # E : Latency=2, extra map slot
|
||||
nop # E : with cmovne
|
||||
|
||||
bic a0, 7, t0
|
||||
cmovne t2, 2, t2 # E : Latency=2, extra map slot
|
||||
nop # E : with cmovne
|
||||
nop
|
||||
|
||||
cmovne t1, 1, t1 # E : Latency=2, extra map slot
|
||||
nop # E : with cmovne
|
||||
addq t0, t3, t0 # E :
|
||||
addq t1, t2, t1 # E :
|
||||
|
||||
addq t0, t1, t0 # E :
|
||||
addq t0, t4, t0 # add one if we filled the buffer
|
||||
subq t0, v0, v0 # find string length
|
||||
ret # L0 :
|
||||
|
||||
.align 4
|
||||
$zerolength:
|
||||
nop
|
||||
nop
|
||||
nop
|
||||
clr v0
|
||||
|
||||
$exception:
|
||||
nop
|
||||
nop
|
||||
nop
|
||||
ret
|
||||
|
||||
.end __strncpy_from_user
|
||||
|
|
@ -1,107 +0,0 @@
|
|||
/*
|
||||
* arch/alpha/lib/ev67-strlen_user.S
|
||||
* 21264 version contributed by Rick Gorton <rick.gorton@api-networks.com>
|
||||
*
|
||||
* Return the length of the string including the NULL terminator
|
||||
* (strlen+1) or zero if an error occurred.
|
||||
*
|
||||
* In places where it is critical to limit the processing time,
|
||||
* and the data is not trusted, strnlen_user() should be used.
|
||||
* It will return a value greater than its second argument if
|
||||
* that limit would be exceeded. This implementation is allowed
|
||||
* to access memory beyond the limit, but will not cross a page
|
||||
* boundary when doing so.
|
||||
*
|
||||
* Much of the information about 21264 scheduling/coding comes from:
|
||||
* Compiler Writer's Guide for the Alpha 21264
|
||||
* abbreviated as 'CWG' in other comments here
|
||||
* ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
|
||||
* Scheduling notation:
|
||||
* E - either cluster
|
||||
* U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
|
||||
* L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
|
||||
* Try not to change the actual algorithm if possible for consistency.
|
||||
*/
|
||||
|
||||
#include <asm/regdef.h>
|
||||
|
||||
|
||||
/* Allow an exception for an insn; exit if we get one. */
|
||||
#define EX(x,y...) \
|
||||
99: x,##y; \
|
||||
.section __ex_table,"a"; \
|
||||
.long 99b - .; \
|
||||
lda v0, $exception-99b(zero); \
|
||||
.previous
|
||||
|
||||
|
||||
.set noreorder
|
||||
.set noat
|
||||
.text
|
||||
|
||||
.globl __strlen_user
|
||||
.ent __strlen_user
|
||||
.frame sp, 0, ra
|
||||
|
||||
.align 4
|
||||
__strlen_user:
|
||||
ldah a1, 32767(zero) # do not use plain strlen_user() for strings
|
||||
# that might be almost 2 GB long; you should
|
||||
# be using strnlen_user() instead
|
||||
nop
|
||||
nop
|
||||
nop
|
||||
|
||||
.globl __strnlen_user
|
||||
|
||||
.align 4
|
||||
__strnlen_user:
|
||||
.prologue 0
|
||||
EX( ldq_u t0, 0(a0) ) # L : load first quadword (a0 may be misaligned)
|
||||
lda t1, -1(zero) # E :
|
||||
|
||||
insqh t1, a0, t1 # U :
|
||||
andnot a0, 7, v0 # E :
|
||||
or t1, t0, t0 # E :
|
||||
subq a0, 1, a0 # E : get our +1 for the return
|
||||
|
||||
cmpbge zero, t0, t1 # E : t1 <- bitmask: bit i == 1 <==> i-th byte == 0
|
||||
subq a1, 7, t2 # E :
|
||||
subq a0, v0, t0 # E :
|
||||
bne t1, $found # U :
|
||||
|
||||
addq t2, t0, t2 # E :
|
||||
addq a1, 1, a1 # E :
|
||||
nop # E :
|
||||
nop # E :
|
||||
|
||||
.align 4
|
||||
$loop: ble t2, $limit # U :
|
||||
EX( ldq t0, 8(v0) ) # L :
|
||||
nop # E :
|
||||
nop # E :
|
||||
|
||||
cmpbge zero, t0, t1 # E :
|
||||
subq t2, 8, t2 # E :
|
||||
addq v0, 8, v0 # E : addr += 8
|
||||
beq t1, $loop # U :
|
||||
|
||||
$found: cttz t1, t2 # U0 :
|
||||
addq v0, t2, v0 # E :
|
||||
subq v0, a0, v0 # E :
|
||||
ret # L0 :
|
||||
|
||||
$exception:
|
||||
nop
|
||||
nop
|
||||
nop
|
||||
ret
|
||||
|
||||
.align 4 # currently redundant
|
||||
$limit:
|
||||
nop
|
||||
nop
|
||||
subq a1, t2, v0
|
||||
ret
|
||||
|
||||
.end __strlen_user
|
||||
|
|
@ -1,91 +0,0 @@
|
|||
/*
|
||||
* arch/alpha/lib/strlen_user.S
|
||||
*
|
||||
* Return the length of the string including the NUL terminator
|
||||
* (strlen+1) or zero if an error occurred.
|
||||
*
|
||||
* In places where it is critical to limit the processing time,
|
||||
* and the data is not trusted, strnlen_user() should be used.
|
||||
* It will return a value greater than its second argument if
|
||||
* that limit would be exceeded. This implementation is allowed
|
||||
* to access memory beyond the limit, but will not cross a page
|
||||
* boundary when doing so.
|
||||
*/
|
||||
|
||||
#include <asm/regdef.h>
|
||||
|
||||
|
||||
/* Allow an exception for an insn; exit if we get one. */
|
||||
#define EX(x,y...) \
|
||||
99: x,##y; \
|
||||
.section __ex_table,"a"; \
|
||||
.long 99b - .; \
|
||||
lda v0, $exception-99b(zero); \
|
||||
.previous
|
||||
|
||||
|
||||
.set noreorder
|
||||
.set noat
|
||||
.text
|
||||
|
||||
.globl __strlen_user
|
||||
.ent __strlen_user
|
||||
.frame sp, 0, ra
|
||||
|
||||
.align 3
|
||||
__strlen_user:
|
||||
ldah a1, 32767(zero) # do not use plain strlen_user() for strings
|
||||
# that might be almost 2 GB long; you should
|
||||
# be using strnlen_user() instead
|
||||
|
||||
.globl __strnlen_user
|
||||
|
||||
.align 3
|
||||
__strnlen_user:
|
||||
.prologue 0
|
||||
|
||||
EX( ldq_u t0, 0(a0) ) # load first quadword (a0 may be misaligned)
|
||||
lda t1, -1(zero)
|
||||
insqh t1, a0, t1
|
||||
andnot a0, 7, v0
|
||||
or t1, t0, t0
|
||||
subq a0, 1, a0 # get our +1 for the return
|
||||
cmpbge zero, t0, t1 # t1 <- bitmask: bit i == 1 <==> i-th byte == 0
|
||||
subq a1, 7, t2
|
||||
subq a0, v0, t0
|
||||
bne t1, $found
|
||||
|
||||
addq t2, t0, t2
|
||||
addq a1, 1, a1
|
||||
|
||||
.align 3
|
||||
$loop: ble t2, $limit
|
||||
EX( ldq t0, 8(v0) )
|
||||
subq t2, 8, t2
|
||||
addq v0, 8, v0 # addr += 8
|
||||
cmpbge zero, t0, t1
|
||||
beq t1, $loop
|
||||
|
||||
$found: negq t1, t2 # clear all but least set bit
|
||||
and t1, t2, t1
|
||||
|
||||
and t1, 0xf0, t2 # binary search for that set bit
|
||||
and t1, 0xcc, t3
|
||||
and t1, 0xaa, t4
|
||||
cmovne t2, 4, t2
|
||||
cmovne t3, 2, t3
|
||||
cmovne t4, 1, t4
|
||||
addq t2, t3, t2
|
||||
addq v0, t4, v0
|
||||
addq v0, t2, v0
|
||||
nop # dual issue next two on ev4 and ev5
|
||||
subq v0, a0, v0
|
||||
$exception:
|
||||
ret
|
||||
|
||||
.align 3 # currently redundant
|
||||
$limit:
|
||||
subq a1, t2, v0
|
||||
ret
|
||||
|
||||
.end __strlen_user
|
||||
|
|
@ -1,339 +0,0 @@
|
|||
/*
|
||||
* arch/alpha/lib/strncpy_from_user.S
|
||||
* Contributed by Richard Henderson (rth@tamu.edu)
|
||||
*
|
||||
* Just like strncpy except in the return value:
|
||||
*
|
||||
* -EFAULT if an exception occurs before the terminator is copied.
|
||||
* N if the buffer filled.
|
||||
*
|
||||
* Otherwise the length of the string is returned.
|
||||
*/
|
||||
|
||||
|
||||
#include <asm/errno.h>
|
||||
#include <asm/regdef.h>
|
||||
|
||||
|
||||
/* Allow an exception for an insn; exit if we get one. */
|
||||
#define EX(x,y...) \
|
||||
99: x,##y; \
|
||||
.section __ex_table,"a"; \
|
||||
.long 99b - .; \
|
||||
lda $31, $exception-99b($0); \
|
||||
.previous
|
||||
|
||||
|
||||
.set noat
|
||||
.set noreorder
|
||||
.text
|
||||
|
||||
.globl __strncpy_from_user
|
||||
.ent __strncpy_from_user
|
||||
.frame $30, 0, $26
|
||||
.prologue 0
|
||||
|
||||
.align 3
|
||||
$aligned:
|
||||
/* On entry to this basic block:
|
||||
t0 == the first destination word for masking back in
|
||||
t1 == the first source word. */
|
||||
|
||||
/* Create the 1st output word and detect 0's in the 1st input word. */
|
||||
lda t2, -1 # e1 : build a mask against false zero
|
||||
mskqh t2, a1, t2 # e0 : detection in the src word
|
||||
mskqh t1, a1, t3 # e0 :
|
||||
ornot t1, t2, t2 # .. e1 :
|
||||
mskql t0, a1, t0 # e0 : assemble the first output word
|
||||
cmpbge zero, t2, t8 # .. e1 : bits set iff null found
|
||||
or t0, t3, t0 # e0 :
|
||||
beq a2, $a_eoc # .. e1 :
|
||||
bne t8, $a_eos # .. e1 :
|
||||
|
||||
/* On entry to this basic block:
|
||||
t0 == a source word not containing a null. */
|
||||
|
||||
$a_loop:
|
||||
stq_u t0, 0(a0) # e0 :
|
||||
addq a0, 8, a0 # .. e1 :
|
||||
EX( ldq_u t0, 0(a1) ) # e0 :
|
||||
addq a1, 8, a1 # .. e1 :
|
||||
subq a2, 1, a2 # e0 :
|
||||
cmpbge zero, t0, t8 # .. e1 (stall)
|
||||
beq a2, $a_eoc # e1 :
|
||||
beq t8, $a_loop # e1 :
|
||||
|
||||
/* Take care of the final (partial) word store. At this point
|
||||
the end-of-count bit is set in t8 iff it applies.
|
||||
|
||||
On entry to this basic block we have:
|
||||
t0 == the source word containing the null
|
||||
t8 == the cmpbge mask that found it. */
|
||||
|
||||
$a_eos:
|
||||
negq t8, t12 # e0 : find low bit set
|
||||
and t8, t12, t12 # e1 (stall)
|
||||
|
||||
/* For the sake of the cache, don't read a destination word
|
||||
if we're not going to need it. */
|
||||
and t12, 0x80, t6 # e0 :
|
||||
bne t6, 1f # .. e1 (zdb)
|
||||
|
||||
/* We're doing a partial word store and so need to combine
|
||||
our source and original destination words. */
|
||||
ldq_u t1, 0(a0) # e0 :
|
||||
subq t12, 1, t6 # .. e1 :
|
||||
or t12, t6, t8 # e0 :
|
||||
unop #
|
||||
zapnot t0, t8, t0 # e0 : clear src bytes > null
|
||||
zap t1, t8, t1 # .. e1 : clear dst bytes <= null
|
||||
or t0, t1, t0 # e1 :
|
||||
|
||||
1: stq_u t0, 0(a0)
|
||||
br $finish_up
|
||||
|
||||
/* Add the end-of-count bit to the eos detection bitmask. */
|
||||
$a_eoc:
|
||||
or t10, t8, t8
|
||||
br $a_eos
|
||||
|
||||
/*** The Function Entry Point ***/
|
||||
.align 3
|
||||
__strncpy_from_user:
|
||||
mov a0, v0 # save the string start
|
||||
beq a2, $zerolength
|
||||
|
||||
/* Are source and destination co-aligned? */
|
||||
xor a0, a1, t1 # e0 :
|
||||
and a0, 7, t0 # .. e1 : find dest misalignment
|
||||
and t1, 7, t1 # e0 :
|
||||
addq a2, t0, a2 # .. e1 : bias count by dest misalignment
|
||||
subq a2, 1, a2 # e0 :
|
||||
and a2, 7, t2 # e1 :
|
||||
srl a2, 3, a2 # e0 : a2 = loop counter = (count - 1)/8
|
||||
addq zero, 1, t10 # .. e1 :
|
||||
sll t10, t2, t10 # e0 : t10 = bitmask of last count byte
|
||||
bne t1, $unaligned # .. e1 :
|
||||
|
||||
/* We are co-aligned; take care of a partial first word. */
|
||||
|
||||
EX( ldq_u t1, 0(a1) ) # e0 : load first src word
|
||||
addq a1, 8, a1 # .. e1 :
|
||||
|
||||
beq t0, $aligned # avoid loading dest word if not needed
|
||||
ldq_u t0, 0(a0) # e0 :
|
||||
br $aligned # .. e1 :
|
||||
|
||||
|
||||
/* The source and destination are not co-aligned. Align the destination
|
||||
and cope. We have to be very careful about not reading too much and
|
||||
causing a SEGV. */
|
||||
|
||||
.align 3
|
||||
$u_head:
|
||||
/* We know just enough now to be able to assemble the first
|
||||
full source word. We can still find a zero at the end of it
|
||||
that prevents us from outputting the whole thing.
|
||||
|
||||
On entry to this basic block:
|
||||
t0 == the first dest word, unmasked
|
||||
t1 == the shifted low bits of the first source word
|
||||
t6 == bytemask that is -1 in dest word bytes */
|
||||
|
||||
EX( ldq_u t2, 8(a1) ) # e0 : load second src word
|
||||
addq a1, 8, a1 # .. e1 :
|
||||
mskql t0, a0, t0 # e0 : mask trailing garbage in dst
|
||||
extqh t2, a1, t4 # e0 :
|
||||
or t1, t4, t1 # e1 : first aligned src word complete
|
||||
mskqh t1, a0, t1 # e0 : mask leading garbage in src
|
||||
or t0, t1, t0 # e0 : first output word complete
|
||||
or t0, t6, t6 # e1 : mask original data for zero test
|
||||
cmpbge zero, t6, t8 # e0 :
|
||||
beq a2, $u_eocfin # .. e1 :
|
||||
bne t8, $u_final # e1 :
|
||||
|
||||
lda t6, -1 # e1 : mask out the bits we have
|
||||
mskql t6, a1, t6 # e0 : already seen
|
||||
stq_u t0, 0(a0) # e0 : store first output word
|
||||
or t6, t2, t2 # .. e1 :
|
||||
cmpbge zero, t2, t8 # e0 : find nulls in second partial
|
||||
addq a0, 8, a0 # .. e1 :
|
||||
subq a2, 1, a2 # e0 :
|
||||
bne t8, $u_late_head_exit # .. e1 :
|
||||
|
||||
/* Finally, we've got all the stupid leading edge cases taken care
|
||||
of and we can set up to enter the main loop. */
|
||||
|
||||
extql t2, a1, t1 # e0 : position hi-bits of lo word
|
||||
EX( ldq_u t2, 8(a1) ) # .. e1 : read next high-order source word
|
||||
addq a1, 8, a1 # e0 :
|
||||
cmpbge zero, t2, t8 # e1 (stall)
|
||||
beq a2, $u_eoc # e1 :
|
||||
bne t8, $u_eos # e1 :
|
||||
|
||||
/* Unaligned copy main loop. In order to avoid reading too much,
|
||||
the loop is structured to detect zeros in aligned source words.
|
||||
This has, unfortunately, effectively pulled half of a loop
|
||||
iteration out into the head and half into the tail, but it does
|
||||
prevent nastiness from accumulating in the very thing we want
|
||||
to run as fast as possible.
|
||||
|
||||
On entry to this basic block:
|
||||
t1 == the shifted high-order bits from the previous source word
|
||||
t2 == the unshifted current source word
|
||||
|
||||
We further know that t2 does not contain a null terminator. */
|
||||
|
||||
.align 3
|
||||
$u_loop:
|
||||
extqh t2, a1, t0 # e0 : extract high bits for current word
|
||||
addq a1, 8, a1 # .. e1 :
|
||||
extql t2, a1, t3 # e0 : extract low bits for next time
|
||||
addq a0, 8, a0 # .. e1 :
|
||||
or t0, t1, t0 # e0 : current dst word now complete
|
||||
EX( ldq_u t2, 0(a1) ) # .. e1 : load high word for next time
|
||||
stq_u t0, -8(a0) # e0 : save the current word
|
||||
mov t3, t1 # .. e1 :
|
||||
subq a2, 1, a2 # e0 :
|
||||
cmpbge zero, t2, t8 # .. e1 : test new word for eos
|
||||
beq a2, $u_eoc # e1 :
|
||||
beq t8, $u_loop # e1 :
|
||||
|
||||
/* We've found a zero somewhere in the source word we just read.
|
||||
If it resides in the lower half, we have one (probably partial)
|
||||
word to write out, and if it resides in the upper half, we
|
||||
have one full and one partial word left to write out.
|
||||
|
||||
On entry to this basic block:
|
||||
t1 == the shifted high-order bits from the previous source word
|
||||
t2 == the unshifted current source word. */
|
||||
$u_eos:
|
||||
extqh t2, a1, t0 # e0 :
|
||||
or t0, t1, t0 # e1 : first (partial) source word complete
|
||||
|
||||
cmpbge zero, t0, t8 # e0 : is the null in this first bit?
|
||||
bne t8, $u_final # .. e1 (zdb)
|
||||
|
||||
stq_u t0, 0(a0) # e0 : the null was in the high-order bits
|
||||
addq a0, 8, a0 # .. e1 :
|
||||
subq a2, 1, a2 # e1 :
|
||||
|
||||
$u_late_head_exit:
|
||||
extql t2, a1, t0 # .. e0 :
|
||||
cmpbge zero, t0, t8 # e0 :
|
||||
or t8, t10, t6 # e1 :
|
||||
cmoveq a2, t6, t8 # e0 :
|
||||
nop # .. e1 :
|
||||
|
||||
/* Take care of a final (probably partial) result word.
|
||||
On entry to this basic block:
|
||||
t0 == assembled source word
|
||||
t8 == cmpbge mask that found the null. */
|
||||
$u_final:
|
||||
negq t8, t6 # e0 : isolate low bit set
|
||||
and t6, t8, t12 # e1 :
|
||||
|
||||
and t12, 0x80, t6 # e0 : avoid dest word load if we can
|
||||
bne t6, 1f # .. e1 (zdb)
|
||||
|
||||
ldq_u t1, 0(a0) # e0 :
|
||||
subq t12, 1, t6 # .. e1 :
|
||||
or t6, t12, t8 # e0 :
|
||||
zapnot t0, t8, t0 # .. e1 : kill source bytes > null
|
||||
zap t1, t8, t1 # e0 : kill dest bytes <= null
|
||||
or t0, t1, t0 # e1 :
|
||||
|
||||
1: stq_u t0, 0(a0) # e0 :
|
||||
br $finish_up
|
||||
|
||||
$u_eoc: # end-of-count
|
||||
extqh t2, a1, t0
|
||||
or t0, t1, t0
|
||||
cmpbge zero, t0, t8
|
||||
|
||||
$u_eocfin: # end-of-count, final word
|
||||
or t10, t8, t8
|
||||
br $u_final
|
||||
|
||||
/* Unaligned copy entry point. */
|
||||
.align 3
|
||||
$unaligned:
|
||||
|
||||
EX( ldq_u t1, 0(a1) ) # e0 : load first source word
|
||||
|
||||
and a0, 7, t4 # .. e1 : find dest misalignment
|
||||
and a1, 7, t5 # e0 : find src misalignment
|
||||
|
||||
/* Conditionally load the first destination word and a bytemask
|
||||
with 0xff indicating that the destination byte is sacrosanct. */
|
||||
|
||||
mov zero, t0 # .. e1 :
|
||||
mov zero, t6 # e0 :
|
||||
beq t4, 1f # .. e1 :
|
||||
ldq_u t0, 0(a0) # e0 :
|
||||
lda t6, -1 # .. e1 :
|
||||
mskql t6, a0, t6 # e0 :
|
||||
1:
|
||||
subq a1, t4, a1 # .. e1 : sub dest misalignment from src addr
|
||||
|
||||
/* If source misalignment is larger than dest misalignment, we need
|
||||
extra startup checks to avoid SEGV. */
|
||||
|
||||
cmplt t4, t5, t12 # e1 :
|
||||
extql t1, a1, t1 # .. e0 : shift src into place
|
||||
lda t2, -1 # e0 : for creating masks later
|
||||
beq t12, $u_head # e1 :
|
||||
|
||||
mskqh t2, t5, t2 # e0 : begin src byte validity mask
|
||||
cmpbge zero, t1, t8 # .. e1 : is there a zero?
|
||||
extql t2, a1, t2 # e0 :
|
||||
or t8, t10, t5 # .. e1 : test for end-of-count too
|
||||
cmpbge zero, t2, t3 # e0 :
|
||||
cmoveq a2, t5, t8 # .. e1 :
|
||||
andnot t8, t3, t8 # e0 :
|
||||
beq t8, $u_head # .. e1 (zdb)
|
||||
|
||||
/* At this point we've found a zero in the first partial word of
|
||||
the source. We need to isolate the valid source data and mask
|
||||
it into the original destination data. (Incidentally, we know
|
||||
that we'll need at least one byte of that original dest word.) */
|
||||
|
||||
ldq_u t0, 0(a0) # e0 :
|
||||
negq t8, t6 # .. e1 : build bitmask of bytes <= zero
|
||||
mskqh t1, t4, t1 # e0 :
|
||||
and t6, t8, t12 # .. e1 :
|
||||
subq t12, 1, t6 # e0 :
|
||||
or t6, t12, t8 # e1 :
|
||||
|
||||
zapnot t2, t8, t2 # e0 : prepare source word; mirror changes
|
||||
zapnot t1, t8, t1 # .. e1 : to source validity mask
|
||||
|
||||
andnot t0, t2, t0 # e0 : zero place for source to reside
|
||||
or t0, t1, t0 # e1 : and put it there
|
||||
stq_u t0, 0(a0) # e0 :
|
||||
|
||||
$finish_up:
|
||||
zapnot t0, t12, t4 # was last byte written null?
|
||||
cmovne t4, 1, t4
|
||||
|
||||
and t12, 0xf0, t3 # binary search for the address of the
|
||||
and t12, 0xcc, t2 # last byte written
|
||||
and t12, 0xaa, t1
|
||||
bic a0, 7, t0
|
||||
cmovne t3, 4, t3
|
||||
cmovne t2, 2, t2
|
||||
cmovne t1, 1, t1
|
||||
addq t0, t3, t0
|
||||
addq t1, t2, t1
|
||||
addq t0, t1, t0
|
||||
addq t0, t4, t0 # add one if we filled the buffer
|
||||
|
||||
subq t0, v0, v0 # find string length
|
||||
ret
|
||||
|
||||
$zerolength:
|
||||
clr v0
|
||||
$exception:
|
||||
ret
|
||||
|
||||
.end __strncpy_from_user
|
||||
Reference in New Issue