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gthr_aux: Backport assembly changes from master
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@lhmouse
lhmouse committed Oct 29, 2024
1 parent 7946e54 commit 25c836e
Showing 1 changed file with 66 additions and 63 deletions.
129 changes: 66 additions & 63 deletions mcfgthread/gthr_aux.c
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Original file line number Diff line number Diff line change
Expand Up @@ -11,24 +11,20 @@
#include "gthr_aux.h"
#include "xglobals.h"

__MCF_DLLEXPORT
void
__MCF_gthr_call_once_seh_take_over(_MCF_once* once, __MCF_cxa_dtor_cdecl* init_proc, void* arg);
__cdecl
__MCF_gthr_do_call_once_seh_take_over(_MCF_once* once, __MCF_cxa_dtor_union init_proc, void* arg);

__asm__ (
# ifdef DLL_EXPORT
".section \".drectve\" \n\t"
".ascii \" -export:\\\"__MCF_gthr_call_once_seh_take_over\\\"\" \n\t"
# endif
#if defined __i386__ || defined __amd64__
/* This is required by Clang, where `-masm=intel` doesn't affect basic asm. */
".intel_syntax noprefix \n\t"
".intel_syntax noprefix \n"
#endif
#if defined __i386__
/* On x86, SEH is stack-based. */
".text \n\t"
".globl ___MCF_gthr_call_once_seh_take_over \n\t"
".def ___MCF_gthr_call_once_seh_take_over; .scl 2; .type 32; .endef \n\t"
"___MCF_gthr_call_once_seh_take_over: \n\t"
".globl ___MCF_gthr_do_call_once_seh_take_over \n"
".def ___MCF_gthr_do_call_once_seh_take_over; .scl 2; .type 32; .endef \n"
"___MCF_gthr_do_call_once_seh_take_over: \n"
/* The stack is used as follows:
*
* -24: argument to subroutines
Expand All @@ -44,35 +40,33 @@ __asm__ (
* 16: `arg`
*/
# define __MCF_SEH_ONCE_PTR_DISPLACEMENT 16
" push ebp \n\t"
" mov ebp, esp \n\t"
" sub esp, 24 \n\t"
" push ebp \n"
" mov ebp, esp \n"
/* Install an SEH handler. */
" mov eax, DWORD PTR fs:[0] \n\t"
" lea ecx, DWORD PTR [ebp - 8] \n\t"
" mov DWORD PTR [ecx], eax \n\t"
" mov DWORD PTR [ecx + 4], OFFSET _do_call_once_seh_uhandler \n\t"
" mov DWORD PTR fs:[0], ecx \n\t"
/* Make the call `(*init_proc) (arg)`. */
" mov eax, DWORD PTR [ebp + 12] \n\t"
" mov ecx, DWORD PTR [ebp + 16] \n\t"
" mov DWORD PTR [ebp - 24], ecx \n\t"
" call eax \n\t"
" push OFFSET _do_call_once_seh_uhandler \n"
" push fs:[0] \n"
" mov fs:[0], esp \n"
/* Make the call `(*init_proc) (arg)`. The argument is passed both via the
* ECX register and on the stack, to allow both `__cdecl` and `__thiscall`
* functions to work properly. */
" mov ecx, [ebp + 16] \n"
" sub esp, 12 \n"
" push ecx \n"
" call [ebp + 12] \n"
/* Dismantle the SEH handler. */
" mov ecx, DWORD PTR [ebp - 8] \n\t"
" mov DWORD PTR fs:[0], ecx \n\t"
" add esp, 16 \n"
" pop fs:[0] \n"
/* Disarm the once flag with a tail call. */
" leave \n\t"
" jmp __MCF_once_release \n\t"
" leave \n"
" jmp __MCF_once_release \n"
#else
/* Otherwise, SEH is table-based. `@unwind` without `@except` works only on
* x86-64 and not on ARM, so let's keep both for simplicity. */
".text \n\t"
".globl __MCF_gthr_call_once_seh_take_over \n\t"
".def __MCF_gthr_call_once_seh_take_over; .scl 2; .type 32; .endef \n\t"
"__MCF_gthr_call_once_seh_take_over: \n\t"
".seh_proc __MCF_gthr_call_once_seh_take_over \n\t"
".seh_handler do_call_once_seh_uhandler, @except, @unwind \n\t"
".globl __MCF_gthr_do_call_once_seh_take_over \n"
".def __MCF_gthr_do_call_once_seh_take_over; .scl 2; .type 32; .endef \n"
"__MCF_gthr_do_call_once_seh_take_over: \n"
".seh_proc __MCF_gthr_do_call_once_seh_take_over \n"
".seh_handler do_call_once_seh_uhandler, @except, @unwind \n"
# if defined __amd64__
/* The stack is used as follows:
*
Expand All @@ -88,22 +82,24 @@ __asm__ (
* 40: unused
*/
# define __MCF_SEH_ONCE_PTR_DISPLACEMENT 16
" push rbp \n\t"
".seh_pushreg rbp \n\t"
" mov rbp, rsp \n\t"
".seh_setframe rbp, 0 \n\t"
" sub rsp, 32 \n\t"
".seh_stackalloc 32 \n\t"
".seh_endprologue \n\t"
" push rbp \n"
".seh_pushreg rbp \n"
" mov rbp, rsp \n"
".seh_setframe rbp, 0 \n"
" sub rsp, 32 \n"
".seh_stackalloc 32 \n"
".seh_endprologue \n"
/* Stash `once` for the handler. */
" mov QWORD PTR [rbp + 16], rcx \n\t"
" mov [rbp + 16], rcx \n"
/* Make the call `(*init_proc) (arg)`. */
" mov rcx, r8 \n\t"
" call rdx \n\t"
/* Disarm the once flag with a tail call. */
" mov rcx, QWORD PTR [rbp + 16] \n\t"
" leave \n\t"
" jmp _MCF_once_release \n\t"
" mov rcx, r8 \n"
" call rdx \n"
/* Disarm the once flag with a tail call. The x64 stack unwinder recognizes
* `add rsp, SIZE` as the start of the epilogue. */
" mov rcx, [rbp + 16] \n"
" add rsp, 32 \n"
" pop rbp \n"
" jmp _MCF_once_release \n"
# elif defined __aarch64__
/* The stack is used as follows:
*
Expand All @@ -114,25 +110,25 @@ __asm__ (
* ENT 32: establisher frame
*/
# define __MCF_SEH_ONCE_PTR_DISPLACEMENT -16
" stp fp, lr, [sp, #-32]! \n\t"
".seh_save_fplr_x 32 \n\t"
" mov fp, sp \n\t"
".seh_set_fp \n\t"
".seh_endprologue \n\t"
" stp fp, lr, [sp, #-32]! \n"
".seh_save_fplr_x 32 \n"
" mov fp, sp \n"
".seh_set_fp \n"
".seh_endprologue \n"
/* Stash `once` for the handler. */
" str x0, [sp, #16] \n\t"
" str x0, [sp, #16] \n"
/* Make the call `(*init_proc) (arg)`. */
" mov x0, x2 \n\t"
" blr x1 \n\t"
" mov x0, x2 \n"
" blr x1 \n"
/* Disarm the once flag with a tail call. */
" ldr x0, [sp, #16] \n\t"
".seh_startepilogue \n\t"
" ldp fp, lr, [sp], #32 \n\t"
".seh_save_fplr_x 32 \n\t"
".seh_endepilogue \n\t"
" b _MCF_once_release \n\t"
" ldr x0, [sp, #16] \n"
".seh_startepilogue \n"
" ldp fp, lr, [sp], #32 \n"
".seh_save_fplr_x 32 \n"
".seh_endepilogue \n"
" b _MCF_once_release \n"
# endif
".seh_endproc \n\t"
".seh_endproc \n"
#endif
);

Expand All @@ -153,6 +149,13 @@ do_call_once_seh_uhandler(EXCEPTION_RECORD* rec, PVOID estab_frame, CONTEXT* ctx
return ExceptionContinueSearch;
}

__MCF_DLLEXPORT
void
__MCF_gthr_call_once_seh_take_over(_MCF_once* once, __MCF_cxa_dtor_union init_proc, void* arg)
{
__MCF_gthr_do_call_once_seh_take_over(once, init_proc, arg);
}

__MCF_DLLEXPORT
int64_t
__MCF_gthr_timeout_from_timespec(const __MCF_timespec* abs_time)
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