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signal/mips: Update (_save|_restore)_fp_context to fail with -EFAULT

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When an instruction to save or restore a register from the stack fails
in _save_fp_context or _restore_fp_context return with -EFAULT.  This
change was made to r2300_fpu.S[1] but it looks like it got lost with
the introduction of EX2[2].  This is also what the other implementation
of _save_fp_context and _restore_fp_context in r4k_fpu.S does, and
what is needed for the callers to be able to handle the error.

Furthermore calling do_exit(SIGSEGV) from bad_stack is wrong because
it does not terminate the entire process it just terminates a single
thread.

As the changed code was the only caller of arch/mips/kernel/syscall.c:bad_stack
remove the problematic and now unused helper function.

Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Maciej Rozycki <macro@orcam.me.uk>
Cc: linux-mips@vger.kernel.org
[1] 35938a00ba86 ("MIPS: Fix ISA I FP sigcontext access violation handling")
[2] f92722dc4545 ("MIPS: Correct MIPS I FP sigcontext layout")
Cc: stable@vger.kernel.org
Fixes: f92722dc4545 ("MIPS: Correct MIPS I FP sigcontext layout")
Acked-by: Maciej W. Rozycki <macro@orcam.me.uk>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Link: https://lkml.kernel.org/r/20211020174406.17889-5-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2021-10-20 12:43:51 -05:00
parent 97cae84827
commit 95bf9d646c
2 changed files with 2 additions and 11 deletions
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4
arch/mips/kernel/r2300_fpu.S
View File

@ -29,8 +29,8 @@
#define EX2(a,b) \
9: a,##b; \
.section __ex_table,"a"; \
PTR 9b,bad_stack; \
PTR 9b+4,bad_stack; \
PTR 9b,fault; \
PTR 9b+4,fault; \
.previous
.set mips1

9
arch/mips/kernel/syscall.c
View File

@ -240,12 +240,3 @@ SYSCALL_DEFINE3(cachectl, char *, addr, int, nbytes, int, op)
{
return -ENOSYS;
}
/*
* If we ever come here the user sp is bad. Zap the process right away.
* Due to the bad stack signaling wouldn't work.
*/
asmlinkage void bad_stack(void)
{
do_exit(SIGSEGV);
}