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c4fca4fdea
Correct a regression introduced with 8453eebd [MIPS: Fix strnlen_user() return value in case of overlong strings.] causing assembler warnings and broken code generated in __strnlen_kernel_nocheck_asm: arch/mips/lib/strnlen_user.S: Assembler messages: arch/mips/lib/strnlen_user.S:64: Warning: Macro instruction expanded into multiple instructions in a branch delay slot with the CPU_DADDI_WORKAROUNDS option set, resulting in the function looping indefinitely upon mounting NFS root. Use conditional assembly to avoid a microMIPS code size regression. Using $at unconditionally would cause such a regression as there are no 16-bit instruction encodings available for ALU operations using this register. Using $v1 unconditionally would produce short microMIPS encodings, but would prevent this register from being used across calls to this function. The extra LI operation introduced is free, replacing a NOP originally scheduled into the delay slot of the branch that follows. Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/10205/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
84 lines
1.8 KiB
ArmAsm
84 lines
1.8 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, 1998, 1999, 2004 by Ralf Baechle
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* Copyright (c) 1999 Silicon Graphics, Inc.
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*/
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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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* Return the size of a string including the ending NUL character up to a
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* maximum of a1 or 0 in case of error.
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*
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* Note: for performance reasons we deliberately accept that a user may
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* make strlen_user and strnlen_user access the first few KSEG0
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* bytes. There's nothing secret there. On 64-bit accessing beyond
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* the maximum is a tad hairier ...
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*/
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.macro __BUILD_STRNLEN_ASM func
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LEAF(__strnlen_\func\()_asm)
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LONG_L v0, TI_ADDR_LIMIT($28) # pointer ok?
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and v0, a0
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bnez v0, .Lfault\@
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FEXPORT(__strnlen_\func\()_nocheck_asm)
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move v0, a0
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PTR_ADDU a1, a0 # stop pointer
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1:
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#ifdef CONFIG_CPU_DADDI_WORKAROUNDS
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.set noat
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li AT, 1
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#endif
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beq v0, a1, 1f # limit reached?
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.ifeqs "\func", "kernel"
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EX(lb, t0, (v0), .Lfault\@)
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.else
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EX(lbe, t0, (v0), .Lfault\@)
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.endif
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.set noreorder
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bnez t0, 1b
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1:
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#ifndef CONFIG_CPU_DADDI_WORKAROUNDS
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PTR_ADDIU v0, 1
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#else
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PTR_ADDU v0, AT
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.set at
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#endif
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.set reorder
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PTR_SUBU v0, a0
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jr ra
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END(__strnlen_\func\()_asm)
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.Lfault\@:
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move v0, zero
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jr ra
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.endm
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#ifndef CONFIG_EVA
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/* Set aliases */
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.global __strnlen_user_asm
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.global __strnlen_user_nocheck_asm
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.set __strnlen_user_asm, __strnlen_kernel_asm
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.set __strnlen_user_nocheck_asm, __strnlen_kernel_nocheck_asm
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#endif
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__BUILD_STRNLEN_ASM kernel
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#ifdef CONFIG_EVA
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.set push
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.set eva
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__BUILD_STRNLEN_ASM user
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.set pop
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#endif
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