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s390: correct CALL_ON_STACK back_chain saving

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Currently CALL_ON_STACK saves r15 as back_chain in the first stack frame of
the stack we about to switch to. But if a function which uses CALL_ON_STACK
calls other function it allocates a stack frame for a callee. In this
case r15 is pointing to a callee stack frame and not a stack frame of
function itself. This results in dummy unwinding entry with random
sp and ip values.

Introduce and utilize current_frame_address macro to get an address of
actual function stack frame.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2019-11-22 12:47:52 +01:00
parent 103b4cca60
commit 7579425777
1 changed files with 14 additions and 1 deletions
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15
arch/s390/include/asm/stacktrace.h
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@ -62,6 +62,17 @@ struct stack_frame {
};
#endif
/*
* Unlike current_stack_pointer() which simply returns current value of %r15
* current_frame_address() returns function stack frame address, which matches
* %r15 upon function invocation. It may differ from %r15 later if function
* allocates stack for local variables or new stack frame to call other
* functions.
*/
#define current_frame_address() \
((unsigned long)__builtin_frame_address(0) - \
offsetof(struct stack_frame, back_chain))
#define CALL_ARGS_0() \
register unsigned long r2 asm("2")
#define CALL_ARGS_1(arg1) \
@ -95,18 +106,20 @@ struct stack_frame {
#define CALL_ON_STACK(fn, stack, nr, args...) \
({ \
unsigned long frame = current_frame_address(); \
CALL_ARGS_##nr(args); \
unsigned long prev; \
\
asm volatile( \
" la %[_prev],0(15)\n" \
" la 15,0(%[_stack])\n" \
" stg %[_prev],%[_bc](15)\n" \
" stg %[_frame],%[_bc](15)\n" \
" brasl 14,%[_fn]\n" \
" la 15,0(%[_prev])\n" \
: [_prev] "=&a" (prev), CALL_FMT_##nr \
[_stack] "a" (stack), \
[_bc] "i" (offsetof(struct stack_frame, back_chain)), \
[_frame] "d" (frame), \
[_fn] "X" (fn) : CALL_CLOBBER_##nr); \
r2; \
})