s390/stack: fix possible register corruption with stack switch helper
commit 67147e96 upstream. The CALL_ON_STACK macro is used to call a C function from inline assembly, and therefore must consider the C ABI, which says that only registers 6-13, and 15 are non-volatile (restored by the called function). The inline assembly incorrectly marks all registers used to pass parameters to the called function as read-only input operands, instead of operands that are read and written to. This might result in register corruption depending on usage, compiler, and compile options. Fix this by marking all operands used to pass parameters as read/write operands. To keep the code simple even register 6, if used, is marked as read-write operand. Fixes: ff340d24 ("s390: add stack switch helper") Cc: <stable@kernel.org> # 4.20 Reviewed-by:Vasily Gorbik <gor@linux.ibm.com> Signed-off-by:
Heiko Carstens <hca@linux.ibm.com> Signed-off-by:
Vasily Gorbik <gor@linux.ibm.com> Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
parent
57378c52
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