619b6e18fc
This complements the generic R4000/R4400 errata workaround code and adds bits for the daddiu problem. In most places it just modifies handwritten assembly code so that the assembler is allowed to use a temporary register as daddiu may now be treated as a macro that expands to a sequence of li and daddu. It is the AT register or, where AT is unavailable or used explicitly for another purpose, an explicitly-named register is selected, using the .set at=<reg> feature added recently to gas. This feature is only used if CONFIG_CPU_DADDI_WORKAROUNDS has been set, so if the workaround remains disabled, the required version of binutils stays unchanged. Similarly, daddiu instructions put in branch delay slots in noreorder fragments are now taken out of them and the assembler is allowed to reorder them itself as possible (which it does making the whole idea of scheduling them into delay slots manually questionable). Also in the very few places where such a simple conversion was not possible, a handcoded longer sequence is implemented. Other than that there are changes to code responsible for building the TLB fault and page clear/copy handlers to avoid daddiu as appropriate. These are only effective if the erratum is verified to be present at the run time. Finally there is a trivial update to __delay(), because it uses daddiu in a branch delay slot. Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
59 lines
1.3 KiB
ArmAsm
59 lines
1.3 KiB
ArmAsm
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (c) 1996, 1999 by Ralf Baechle
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*/
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#include <linux/errno.h>
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#include <asm/asm.h>
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#include <asm/asm-offsets.h>
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#include <asm/regdef.h>
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#define EX(insn,reg,addr,handler) \
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9: insn reg, addr; \
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.section __ex_table,"a"; \
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PTR 9b, handler; \
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.previous
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/*
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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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*/
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/*
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* Ugly special case have to check: we might get passed a user space
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* pointer which wraps into the kernel space. We don't deal with that. If
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* it happens at most some bytes of the exceptions handlers will be copied.
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*/
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LEAF(__strncpy_from_user_asm)
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LONG_L v0, TI_ADDR_LIMIT($28) # pointer ok?
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and v0, a1
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bnez v0, fault
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FEXPORT(__strncpy_from_user_nocheck_asm)
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move v0, zero
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move v1, a1
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.set noreorder
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1: EX(lbu, t0, (v1), fault)
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PTR_ADDIU v1, 1
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beqz t0, 2f
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sb t0, (a0)
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PTR_ADDIU v0, 1
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.set reorder
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PTR_ADDIU a0, 1
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bne v0, a2, 1b
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2: PTR_ADDU t0, a1, v0
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xor t0, a1
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bltz t0, fault
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jr ra # return n
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END(__strncpy_from_user_asm)
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fault: li v0, -EFAULT
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jr ra
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.section __ex_table,"a"
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PTR 1b, fault
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.previous
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