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r11 is a volatile register on PPC as per calling conventions. The safe_syscall code uses it to check if the signal_pending is set during the safe_syscall. When a syscall is interrupted on return from signal handling, the r11 might be corrupted before we retry the syscall leading to a crash. The registers r0-r13 are not to be used here as they have volatile/designated/reserved usages. Change the code to use r14 which is non-volatile. Use SP+16 which is a slot for LR, for save/restore of previous value of r14. SP+16 can be used, as LR is preserved across the syscall. Steps to reproduce: On PPC host, issue `qemu-x86_64 /usr/bin/cc -E -` Attempt Ctrl-C, the issue is reproduced. Reference: https://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html#REG https://openpowerfoundation.org/wp-content/uploads/2016/03/ABI64BitOpenPOWERv1.1_16July2015_pub4.pdf Signed-off-by: Shivaprasad G Bhat <sbhat@linux.vnet.ibm.com> Tested-by: Richard Henderson <richard.henderson@linaro.org> Tested-by: Laurent Vivier <laurent@vivier.eu> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Reviewed-by: Laurent Vivier <laurent@vivier.eu> Message-Id: <153301568965.30312.10498134581068746871.stgit@dhcp-9-109-246-16> Signed-off-by: Laurent Vivier <laurent@vivier.eu> |
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