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Message-ID: <20161113001205.GR5749@port70.net> Date: Sun, 13 Nov 2016 01:12:05 +0100 From: Szabolcs Nagy <nsz@...t70.net> To: musl@...ts.openwall.com Subject: [PATCH v2] fix x86_64 sigreturn trampoline so gdb recognizes it gdb can only unwind across signal handlers if it recognizes the trampoline. on x86_64 this means the pc must be in a function called __restore_rt or if gdb cannot determine the symbol name the instruction sequence must match to what gdb expects. a nop is added before __restore_rt, the __restore alias is removed and size annotation is added to make sure gdb maps any pc value within __restore_rt unambigously to the __restore_rt symbol name. and the instruction sequence got fixed to match what gdb expects. --- arch/x86_64/ksigaction.h | 9 +++++++++ src/signal/x86_64/restore.s | 7 +++---- 2 files changed, 12 insertions(+), 4 deletions(-) create mode 100644 arch/x86_64/ksigaction.h diff --git a/arch/x86_64/ksigaction.h b/arch/x86_64/ksigaction.h new file mode 100644 index 0000000..7743c5c --- /dev/null +++ b/arch/x86_64/ksigaction.h @@ -0,0 +1,9 @@ +struct k_sigaction { + void (*handler)(int); + unsigned long flags; + void (*restorer)(void); + unsigned mask[2]; +}; + +void __restore_rt(); +#define __restore __restore_rt diff --git a/src/signal/x86_64/restore.s b/src/signal/x86_64/restore.s index 682af2d..b5c6e37 100644 --- a/src/signal/x86_64/restore.s +++ b/src/signal/x86_64/restore.s @@ -1,8 +1,7 @@ + nop .global __restore_rt -.global __restore .type __restore_rt,@function -.type __restore,@function __restore_rt: -__restore: - movl $15, %eax + mov $15, %rax syscall +.size __restore_rt,.-__restore_rt -- 2.10.2
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