musl/arch/x32
Rich Felker 54991729fd work around gdb issues recognizing sigreturn trampoline on x86_64
gdb can only backtrace/unwind across signal handlers if it recognizes
the sa_restorer trampoline. for x86_64, gdb first attempts to
determine the symbol name for the function in which the program
counter resides and match it against "__restore_rt". if no name can be
found (e.g. in the case of a stripped binary), the exact instruction
sequence is matched instead.

when matching the function name, however, gdb's unwind code wrongly
considers the interval [sym,sym+size] rather than [sym,sym+size).
thus, if __restore_rt begins immediately after another function, gdb
wrongly identifies pc as lying within the previous adjacent function.
this patch adds a nop before __restore_rt to preclude that
possibility. it also removes the symbol name __restore and replaces it
with a macro since the stability of whether gdb identifies the
function as __restore_rt or __restore is not clear.

for the no-symbols case, the instruction sequence is changed to use
%rax rather than %eax to match what gdb expects.

based on patch by Szabolcs Nagy, with extended description and
corresponding x32 changes added.
2016-11-12 19:54:43 -05:00
..
bits fix preadv2 and pwritev2 syscall numbers on x32 for linux v4.8 2016-10-20 01:27:07 -04:00
atomic_arch.h fix regression disabling use of pause instruction for x86 a_spin 2016-03-29 21:27:28 -04:00
crt_arch.h dynamic linker bootstrap overhaul 2015-04-13 03:04:42 -04:00
ksigaction.h work around gdb issues recognizing sigreturn trampoline on x86_64 2016-11-12 19:54:43 -05:00
pthread_arch.h properly access mcontext_t program counter in cancellation handler 2015-11-02 12:41:49 -05:00
reloc.h new dlstart stage-2 chaining for x86_64 and x32 2015-09-17 07:28:44 +00:00
syscall_arch.h fix dangling pointers in x32 syscall timespec fixup code 2015-05-01 21:22:27 -04:00