diff options
| author | Peter Maydell <peter.maydell@linaro.org> | 2016-06-06 19:56:54 +0100 |
|---|---|---|
| committer | Riku Voipio <riku.voipio@linaro.org> | 2016-06-08 10:13:45 +0300 |
| commit | 9e024732f53b368abdd578e1795bf3d2779ea88a (patch) | |
| tree | aa25d253d5e503ebd13a489e9cb33b38da299d78 /linux-user | |
| parent | 90c0f080fe6fdd8b18691e6e38c853c8a996ad92 (diff) | |
linux-user: provide frame information in x86-64 safe_syscall
Use cfi directives in the x86-64 safe_syscall to allow gdb to get
backtraces right from within it. (In particular this will be
quite a common situation if the user interrupts QEMU while it's
in a blocked safe-syscall: at the point of the syscall insn RBP
is in use for something else, and so gdb can't find the frame then
without assistance.)
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
Diffstat (limited to 'linux-user')
| -rw-r--r-- | linux-user/host/x86_64/safe-syscall.inc.S | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/linux-user/host/x86_64/safe-syscall.inc.S b/linux-user/host/x86_64/safe-syscall.inc.S index dde434c8d7..e09368d450 100644 --- a/linux-user/host/x86_64/safe-syscall.inc.S +++ b/linux-user/host/x86_64/safe-syscall.inc.S @@ -24,6 +24,7 @@ * -1-and-errno-set convention is done by the calling wrapper. */ safe_syscall_base: + .cfi_startproc /* This saves a frame pointer and aligns the stack for the syscall. * (It's unclear if the syscall ABI has the same stack alignment * requirements as the userspace function call ABI, but better safe than @@ -31,6 +32,8 @@ safe_syscall_base: * does not list any ABI differences regarding stack alignment.) */ push %rbp + .cfi_adjust_cfa_offset 8 + .cfi_rel_offset rbp, 0 /* The syscall calling convention isn't the same as the * C one: @@ -70,12 +73,19 @@ safe_syscall_start: safe_syscall_end: /* code path for having successfully executed the syscall */ pop %rbp + .cfi_remember_state + .cfi_def_cfa_offset 8 + .cfi_restore rbp ret return_ERESTARTSYS: /* code path when we didn't execute the syscall */ + .cfi_restore_state mov $-TARGET_ERESTARTSYS, %rax pop %rbp + .cfi_def_cfa_offset 8 + .cfi_restore rbp ret + .cfi_endproc .size safe_syscall_base, .-safe_syscall_base |