ftrace, ia64: IA64 dynamic ftrace support
IA64 dynamic ftrace support. The original _mcount stub for each function is like: alloc r40=ar.pfs,12,8,0 mov r43=r0;; mov r42=b0 mov r41=r1 nop.i 0x0 br.call.sptk.many b0 = _mcount;; The patch convert it to below for nop: [MII] nop.m 0x0 mov r3=ip nop.i 0x0 [MLX] nop.m 0x0 nop.x 0x0;; This isn't completely nop, as there is one instuction 'mov r3=ip', but it should be light and harmless for code follow it. And below is for call [MII] nop.m 0x0 mov r3=ip nop.i 0x0 [MLX] nop.m 0x0 brl.many .;; In this way, only one instruction is changed to convert code between nop and call. This should meet dyn-ftrace's requirement. But this requires CPU support brl instruction, so dyn-ftrace isn't supported for old Itanium system. Assume there are quite few such old system running. Signed-off-by: Shaohua Li <shaohua.li@intel.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Shaohua Li
Ingo Molnar
parent
d3e75ff14b
commit
a14a07b801
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@ -21,6 +21,8 @@ config IA64
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select HAVE_OPROFILE
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select HAVE_KPROBES
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select HAVE_KRETPROBES
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select HAVE_FTRACE_MCOUNT_RECORD
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select HAVE_DYNAMIC_FTRACE if (!ITANIUM)
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select HAVE_FUNCTION_TRACER
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select HAVE_DMA_ATTRS
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select HAVE_KVM
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@ -8,6 +8,19 @@
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extern void _mcount(unsigned long pfs, unsigned long r1, unsigned long b0, unsigned long r0);
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#define mcount _mcount
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#include <asm/kprobes.h>
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/* In IA64, MCOUNT_ADDR is set in link time, so it's not a constant at compile time */
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#define MCOUNT_ADDR (((struct fnptr *)mcount)->ip)
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#define FTRACE_ADDR (((struct fnptr *)ftrace_caller)->ip)
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static inline unsigned long ftrace_call_adjust(unsigned long addr)
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{
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/* second bundle, insn 2 */
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return addr - 0x12;
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}
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struct dyn_arch_ftrace {
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};
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#endif
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#endif /* CONFIG_FUNCTION_TRACER */
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@ -2,6 +2,10 @@
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# Makefile for the linux kernel.
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#
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ifdef CONFIG_DYNAMIC_FTRACE
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CFLAGS_REMOVE_ftrace.o = -pg
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endif
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extra-y := head.o init_task.o vmlinux.lds
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obj-y := acpi.o entry.o efi.o efi_stub.o gate-data.o fsys.o ia64_ksyms.o irq.o irq_ia64.o \
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@ -28,6 +32,7 @@ obj-$(CONFIG_IA64_CYCLONE) += cyclone.o
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obj-$(CONFIG_CPU_FREQ) += cpufreq/
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obj-$(CONFIG_IA64_MCA_RECOVERY) += mca_recovery.o
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obj-$(CONFIG_KPROBES) += kprobes.o jprobes.o
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obj-$(CONFIG_DYNAMIC_FTRACE) += ftrace.o
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obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o crash.o
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obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
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obj-$(CONFIG_IA64_UNCACHED_ALLOCATOR) += uncached.o
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@ -1406,6 +1406,56 @@ GLOBAL_ENTRY(unw_init_running)
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END(unw_init_running)
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#ifdef CONFIG_FUNCTION_TRACER
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#ifdef CONFIG_DYNAMIC_FTRACE
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GLOBAL_ENTRY(_mcount)
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br ftrace_stub
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END(_mcount)
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.here:
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br.ret.sptk.many b0
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GLOBAL_ENTRY(ftrace_caller)
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alloc out0 = ar.pfs, 8, 0, 4, 0
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mov out3 = r0
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;;
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mov out2 = b0
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add r3 = 0x20, r3
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mov out1 = r1;
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br.call.sptk.many b0 = ftrace_patch_gp
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//this might be called from module, so we must patch gp
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ftrace_patch_gp:
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movl gp=__gp
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mov b0 = r3
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;;
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.global ftrace_call;
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ftrace_call:
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{
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.mlx
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nop.m 0x0
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movl r3 = .here;;
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}
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alloc loc0 = ar.pfs, 4, 4, 2, 0
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;;
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mov loc1 = b0
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mov out0 = b0
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mov loc2 = r8
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mov loc3 = r15
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;;
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adds out0 = -MCOUNT_INSN_SIZE, out0
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mov out1 = in2
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mov b6 = r3
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br.call.sptk.many b0 = b6
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;;
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mov ar.pfs = loc0
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mov b0 = loc1
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mov r8 = loc2
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mov r15 = loc3
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br ftrace_stub
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;;
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END(ftrace_caller)
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#else
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GLOBAL_ENTRY(_mcount)
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movl r2 = ftrace_stub
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movl r3 = ftrace_trace_function;;
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@ -1435,6 +1485,7 @@ GLOBAL_ENTRY(_mcount)
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br ftrace_stub
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;;
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END(_mcount)
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#endif
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GLOBAL_ENTRY(ftrace_stub)
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mov r3 = b0
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@ -0,0 +1,206 @@
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/*
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* Dynamic function tracing support.
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*
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* Copyright (C) 2008 Shaohua Li <shaohua.li@intel.com>
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*
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* For licencing details, see COPYING.
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*
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* Defines low-level handling of mcount calls when the kernel
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* is compiled with the -pg flag. When using dynamic ftrace, the
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* mcount call-sites get patched lazily with NOP till they are
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* enabled. All code mutation routines here take effect atomically.
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*/
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <asm/cacheflush.h>
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#include <asm/patch.h>
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/* In IA64, each function will be added below two bundles with -pg option */
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static unsigned char __attribute__((aligned(8)))
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ftrace_orig_code[MCOUNT_INSN_SIZE] = {
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0x02, 0x40, 0x31, 0x10, 0x80, 0x05, /* alloc r40=ar.pfs,12,8,0 */
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0xb0, 0x02, 0x00, 0x00, 0x42, 0x40, /* mov r43=r0;; */
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0x05, 0x00, 0xc4, 0x00, /* mov r42=b0 */
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0x11, 0x48, 0x01, 0x02, 0x00, 0x21, /* mov r41=r1 */
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0x00, 0x00, 0x00, 0x02, 0x00, 0x00, /* nop.i 0x0 */
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0x08, 0x00, 0x00, 0x50 /* br.call.sptk.many b0 = _mcount;; */
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};
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struct ftrace_orig_insn {
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u64 dummy1, dummy2, dummy3;
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u64 dummy4:64-41+13;
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u64 imm20:20;
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u64 dummy5:3;
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u64 sign:1;
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u64 dummy6:4;
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};
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/* mcount stub will be converted below for nop */
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static unsigned char ftrace_nop_code[MCOUNT_INSN_SIZE] = {
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0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
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0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
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0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
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0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* nop.x 0x0;; */
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0x00, 0x00, 0x04, 0x00
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};
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static unsigned char *ftrace_nop_replace(void)
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{
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return ftrace_nop_code;
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}
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/*
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* mcount stub will be converted below for call
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* Note: Just the last instruction is changed against nop
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* */
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static unsigned char __attribute__((aligned(8)))
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ftrace_call_code[MCOUNT_INSN_SIZE] = {
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0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
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0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
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0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
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0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
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0xff, 0xff, 0xff, 0xff, 0x7f, 0x00, /* brl.many .;;*/
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0xf8, 0xff, 0xff, 0xc8
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};
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struct ftrace_call_insn {
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u64 dummy1, dummy2;
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u64 dummy3:48;
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u64 imm39_l:16;
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u64 imm39_h:23;
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u64 dummy4:13;
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u64 imm20:20;
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u64 dummy5:3;
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u64 i:1;
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u64 dummy6:4;
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};
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static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
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{
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struct ftrace_call_insn *code = (void *)ftrace_call_code;
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unsigned long offset = addr - (ip + 0x10);
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code->imm39_l = offset >> 24;
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code->imm39_h = offset >> 40;
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code->imm20 = offset >> 4;
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code->i = offset >> 63;
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return ftrace_call_code;
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}
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static int
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ftrace_modify_code(unsigned long ip, unsigned char *old_code,
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unsigned char *new_code, int do_check)
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{
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unsigned char replaced[MCOUNT_INSN_SIZE];
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/*
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* Note: Due to modules and __init, code can
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* disappear and change, we need to protect against faulting
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* as well as code changing. We do this by using the
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* probe_kernel_* functions.
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*
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* No real locking needed, this code is run through
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* kstop_machine, or before SMP starts.
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*/
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if (!do_check)
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goto skip_check;
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/* read the text we want to modify */
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if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* Make sure it is what we expect it to be */
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if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
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return -EINVAL;
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skip_check:
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/* replace the text with the new text */
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if (probe_kernel_write(((void *)ip), new_code, MCOUNT_INSN_SIZE))
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return -EPERM;
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flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);
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return 0;
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}
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static int ftrace_make_nop_check(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned char __attribute__((aligned(8))) replaced[MCOUNT_INSN_SIZE];
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unsigned long ip = rec->ip;
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if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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if (rec->flags & FTRACE_FL_CONVERTED) {
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struct ftrace_call_insn *call_insn, *tmp_call;
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call_insn = (void *)ftrace_call_code;
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tmp_call = (void *)replaced;
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call_insn->imm39_l = tmp_call->imm39_l;
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call_insn->imm39_h = tmp_call->imm39_h;
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call_insn->imm20 = tmp_call->imm20;
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call_insn->i = tmp_call->i;
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if (memcmp(replaced, ftrace_call_code, MCOUNT_INSN_SIZE) != 0)
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return -EINVAL;
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return 0;
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} else {
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struct ftrace_orig_insn *call_insn, *tmp_call;
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call_insn = (void *)ftrace_orig_code;
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tmp_call = (void *)replaced;
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call_insn->sign = tmp_call->sign;
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call_insn->imm20 = tmp_call->imm20;
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if (memcmp(replaced, ftrace_orig_code, MCOUNT_INSN_SIZE) != 0)
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return -EINVAL;
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return 0;
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}
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}
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int ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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int ret;
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char *new;
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ret = ftrace_make_nop_check(rec, addr);
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if (ret)
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return ret;
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new = ftrace_nop_replace();
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return ftrace_modify_code(rec->ip, NULL, new, 0);
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}
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned long ip = rec->ip;
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unsigned char *old, *new;
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old= ftrace_nop_replace();
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new = ftrace_call_replace(ip, addr);
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return ftrace_modify_code(ip, old, new, 1);
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}
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/* in IA64, _mcount can't directly call ftrace_stub. Only jump is ok */
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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unsigned long ip;
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unsigned long addr = ((struct fnptr *)ftrace_call)->ip;
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if (func == ftrace_stub)
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return 0;
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ip = ((struct fnptr *)func)->ip;
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ia64_patch_imm64(addr + 2, ip);
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flush_icache_range(addr, addr + 16);
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return 0;
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}
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/* run from kstop_machine */
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int __init ftrace_dyn_arch_init(void *data)
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{
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*(unsigned long *)data = 0;
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return 0;
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}
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