Commit 4ac24c09 authored Nov 25, 2019 by Vasily Gorbik

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>

parent f44fa79b

arch/s390/include/asm/stacktrace.h

+2 −2

Original line number	Diff line number	Diff line
		@@ -112,12 +112,12 @@ struct stack_frame {
		\
		asm volatile( \
		" la %[_prev],0(15)\n" \
		" la 15,0(%[_stack])\n" \
		" lg 15,%[_stack]\n" \
		" stg %[_frame],%[_bc](15)\n" \
		" brasl 14,%[_fn]\n" \
		" la 15,0(%[_prev])\n" \
		: [_prev] "=&a" (prev), CALL_FMT_##nr \
		[_stack] "a" (stack), \
		[_stack] "R" (stack), \
		[_bc] "i" (offsetof(struct stack_frame, back_chain)), \
		[_frame] "d" (frame), \
		[_fn] "X" (fn) : CALL_CLOBBER_##nr); \

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