LoongArch: extable: Add a dedicated uaccess handler

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Inspired by commit 2e77a62cb3a6("arm64: extable: add a dedicated uaccess
handler"), do similar to LoongArch to add a dedicated uaccess exception
handler to update registers in exception context and subsequently return
back into the function which faulted, so we remove the need for fixups
specialized to each faulting instruction.

Add gpr-num.h here because we need to map the same GPR names to integer
constants, so that we can use this to build meta-data for the exception
fixups.

The compiler treats gpr 0 as zero rather than $r0, so set it separately
to .L__gpr_num_zero, otherwise the following assembly error will occurs:

{standard input}: Assembler messages:
{standard input}:1074: Error: invalid operands (*UND* and *ABS* sections) for `<<'
{standard input}:1160: Error: invalid operands (*UND* and *ABS* sections) for `<<'
make[1]: *** [scripts/Makefile.build:249: fs/fcntl.o] Error 1

Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

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This commit is contained in:

Youling Tang 2022-12-10 22:39:59 +08:00 • committed by Huacai Chen

parent 26bc824412

commit 672999cfae

5 changed files with 76 additions and 29 deletions

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22

arch/loongarch/include/asm/asm-extable.h

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arch/loongarch/include/asm/futex.h

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22

arch/loongarch/include/asm/gpr-num.h

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17

arch/loongarch/include/asm/uaccess.h

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arch/loongarch/mm/extable.c

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