tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
s390: fix register clobbering in CALL_ON_STACK
CALL_ON_STACK defines and initializes register variables. Inline
assembly which follows might trigger compiler to generate memory access
for "stack" argument (e.g. in case of S390_lowcore.nodat_stack). This
memory access produces a function call under kasan with outline
instrumentation which clobbers registers.
Switch "stack" argument in CALL_ON_STACK helper to use memory reference
constraint and perform load instead.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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arch/s390/include/asm/stacktrace.h
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arch/s390/include/asm/stacktrace.h
···
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\
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asm volatile( \
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" la %[_prev],0(15)\n" \
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-
" la 15,0(%[_stack])\n" \
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" lg 15,%[_stack]\n" \
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" stg %[_frame],%[_bc](15)\n" \
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" brasl 14,%[_fn]\n" \
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" la 15,0(%[_prev])\n" \
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: [_prev] "=&a" (prev), CALL_FMT_##nr \
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[_stack] "a" (stack), \
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[_stack] "R" (stack), \
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[_bc] "i" (offsetof(struct stack_frame, back_chain)), \
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[_frame] "d" (frame), \
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[_fn] "X" (fn) : CALL_CLOBBER_##nr); \