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This patch eliminates one system call per unwind by not using the

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getcontext in libc.

Also cleanup the namespace (check-name-space passes on x86_64 now).
Replace uses of offsets.h with ucontext_i.h.
Rename _x86_64_setcontext to _Ux86_64_setcontext.

TBD: Add CFI annotations for get/setcontext.

Signed-off-by: Paul Pluzhnikov <ppluzhnikov@google.com>
Signed-off-by: Arun Sharma <arun.sharma@google.com>
This commit is contained in:
Arun Sharma 2008-06-16 14:42:16 -06:00 committed by David Mosberger-Tang
parent 649f1fb344
commit ef29eade44
8 changed files with 116 additions and 61 deletions
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12
include/libunwind-x86_64.h
View file

@ -97,22 +97,18 @@ unw_tdep_save_loc_t;
/* On x86_64, we can directly use ucontext_t as the unwind context. */
typedef ucontext_t unw_tdep_context_t;
/* XXX this is not ideal: an application should not be prevented from
using the "getcontext" name just because it's using libunwind. We
can't just use __getcontext() either, because that isn't exported
by glibc... */
#define unw_tdep_getcontext(uc) (getcontext (uc), 0)
#include "libunwind-dynamic.h"
typedef struct
{
/* no x86-64-specific auxiliary proc-info */
}
unw_tdep_proc_info_t;
#include "libunwind-dynamic.h"
#include "libunwind-common.h"
#define unw_tdep_getcontext UNW_ARCH_OBJ(getcontext)
extern int unw_tdep_getcontext (unw_tdep_context_t *);
#define unw_tdep_is_fpreg UNW_ARCH_OBJ(is_fpreg)
extern int unw_tdep_is_fpreg (int);

4
src/Makefile.am
View file

@ -254,7 +254,7 @@ libunwind_la_SOURCES_x86_64_common = $(libunwind_la_SOURCES_common) \
$(dwarf_SOURCES_common) \
elf64.c elf64.h \
x86_64/init.h x86_64/unwind_i.h x86_64/ucontext_i.h \
x86_64/is_fpreg.c x86_64/regname.c x86_64/offsets.h
x86_64/is_fpreg.c x86_64/regname.c
# The list of files that go into libunwind:
libunwind_la_SOURCES_x86_64 = $(libunwind_la_SOURCES_x86_64_common) \
@ -265,7 +265,7 @@ libunwind_la_SOURCES_x86_64 = $(libunwind_la_SOURCES_x86_64_common) \
x86_64/Lcreate_addr_space.c x86_64/Lget_save_loc.c x86_64/Lglobal.c \
x86_64/Linit.c x86_64/Linit_local.c x86_64/Linit_remote.c \
x86_64/Lis_signal_frame.c x86_64/Lget_proc_info.c x86_64/Lregs.c \
x86_64/Lresume.c x86_64/Lstep.c
x86_64/Lresume.c x86_64/Lstep.c x86_64/getcontext.S
# The list of files that go into libunwind-x86_64:
libunwind_x86_64_la_SOURCES_x86_64 = $(libunwind_la_SOURCES_x86_64_common) \

2
src/x86_64/Gresume.c
View file

@ -71,7 +71,7 @@ x86_64_local_resume (unw_addr_space_t as, unw_cursor_t *cursor, void *arg)
{
Debug (8, "resuming at ip=%llx via setcontext()\n",
(unsigned long long) c->dwarf.ip);
_x86_64_setcontext (uc);
_Ux86_64_setcontext (uc);
}
#else
# warning Implement me!

77
src/x86_64/getcontext.S Normal file
View file

@ -0,0 +1,77 @@
/* libunwind - a platform-independent unwind library
Copyright (C) 2008 Google, Inc
Contributed by Paul Pluzhnikov <ppluzhnikov@google.com>
This file is part of libunwind.
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
#include "ucontext_i.h"
/* int _Ux86_64_getcontext (ucontext_t *ucp)
Saves the machine context in UCP necessary for libunwind.
Unlike the libc implementation, we don't save the signal mask
and hence avoid the cost of a system call per unwind.
*/
.global _Ux86_64_getcontext
.type _Ux86_64_getcontext, @function
_Ux86_64_getcontext:
/* Callee saved: RBX, RBP, R12-R15 */
movq %r12, UC_MCONTEXT_GREGS_R12(%rdi)
movq %r13, UC_MCONTEXT_GREGS_R13(%rdi)
movq %r14, UC_MCONTEXT_GREGS_R14(%rdi)
movq %r15, UC_MCONTEXT_GREGS_R15(%rdi)
movq %rbp, UC_MCONTEXT_GREGS_RBP(%rdi)
movq %rbx, UC_MCONTEXT_GREGS_RBX(%rdi)
/* Save argument registers (not strictly needed, but setcontext
restores them, so don't restore garbage). */
movq %r8, UC_MCONTEXT_GREGS_R8(%rdi)
movq %r9, UC_MCONTEXT_GREGS_R9(%rdi)
movq %rdi, UC_MCONTEXT_GREGS_RDI(%rdi)
movq %rsi, UC_MCONTEXT_GREGS_RSI(%rdi)
movq %rdx, UC_MCONTEXT_GREGS_RDX(%rdi)
movq %rax, UC_MCONTEXT_GREGS_RAX(%rdi)
movq %rcx, UC_MCONTEXT_GREGS_RCX(%rdi)
/* Save fp state (not needed, except for setcontext not
restoring garbage). */
leaq UC_MCONTEXT_FPREGS_MEM(%rdi),%r8
movq %r8, UC_MCONTEXT_FPREGS_PTR(%rdi)
fnstenv (%r8)
stmxcsr FPREGS_OFFSET_MXCSR(%r8)
leaq 8(%rsp), %rax /* exclude this call. */
movq %rax, UC_MCONTEXT_GREGS_RSP(%rdi)
movq 0(%rsp), %rax
movq %rax, UC_MCONTEXT_GREGS_RIP(%rdi)
xorq %rax, %rax
retq
#ifdef __linux__
/* We do not need executable stack. */
.section .note.GNU-stack,"",@progbits
#endif

29
src/x86_64/offsets.h
View file

@ -1,29 +0,0 @@
/* This used to be a generated file. But then it breaks cross compilation.
* So use the method used by other architectures.
*/
#ifndef OFFSETS_H
#define OFFSETS_H
#define REG_OFFSET_RAX 144
#define REG_OFFSET_RBX 128
#define REG_OFFSET_RCX 152
#define REG_OFFSET_RDX 136
#define REG_OFFSET_RDI 104
#define REG_OFFSET_RSI 112
#define REG_OFFSET_RSP 160
#define REG_OFFSET_RBP 120
#define REG_OFFSET_R8 40
#define REG_OFFSET_R9 48
#define REG_OFFSET_R10 56
#define REG_OFFSET_R11 64
#define REG_OFFSET_R12 72
#define REG_OFFSET_R13 80
#define REG_OFFSET_R14 88
#define REG_OFFSET_R15 96
#define REG_OFFSET_R15 96
#define REG_OFFSET_R15 96
#define REG_OFFSET_RIP 168
#define REG_OFFSET_FPREGS_PTR 224
#define FPREG_OFFSET_MXCR 24
#endif /* OFFSETS_H */

49
src/x86_64/setcontext.S
View file

@ -23,38 +23,45 @@ LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
#include "offsets.h"
#include "ucontext_i.h"
.global _x86_64_setcontext
_x86_64_setcontext:
/* int _Ux86_64_setcontext (const ucontext_t *ucp)
Restores the machine context provided.
Unlike the libc implementation, doesn't clobber %rax
*/
.global _Ux86_64_setcontext
_Ux86_64_setcontext:
/* restore fp state */
mov REG_OFFSET_FPREGS_PTR(%rdi),%r8
mov UC_MCONTEXT_FPREGS_PTR(%rdi),%r8
fldenv (%r8)
ldmxcsr FPREG_OFFSET_MXCR(%r8)
ldmxcsr FPREGS_OFFSET_MXCSR(%r8)
/* restore the rest of the state */
mov REG_OFFSET_R8(%rdi),%r8
mov REG_OFFSET_R9(%rdi),%r9
mov REG_OFFSET_RBX(%rdi),%rbx
mov REG_OFFSET_RBP(%rdi),%rbp
mov REG_OFFSET_R12(%rdi),%r12
mov REG_OFFSET_R13(%rdi),%r13
mov REG_OFFSET_R14(%rdi),%r14
mov REG_OFFSET_R15(%rdi),%r15
mov REG_OFFSET_RSI(%rdi),%rsi
mov REG_OFFSET_RDX(%rdi),%rdx
mov REG_OFFSET_RAX(%rdi),%rax
mov REG_OFFSET_RCX(%rdi),%rcx
mov REG_OFFSET_RSP(%rdi),%rsp
mov UC_MCONTEXT_GREGS_R8(%rdi),%r8
mov UC_MCONTEXT_GREGS_R9(%rdi),%r9
mov UC_MCONTEXT_GREGS_RBX(%rdi),%rbx
mov UC_MCONTEXT_GREGS_RBP(%rdi),%rbp
mov UC_MCONTEXT_GREGS_R12(%rdi),%r12
mov UC_MCONTEXT_GREGS_R13(%rdi),%r13
mov UC_MCONTEXT_GREGS_R14(%rdi),%r14
mov UC_MCONTEXT_GREGS_R15(%rdi),%r15
mov UC_MCONTEXT_GREGS_RSI(%rdi),%rsi
mov UC_MCONTEXT_GREGS_RDX(%rdi),%rdx
mov UC_MCONTEXT_GREGS_RAX(%rdi),%rax
mov UC_MCONTEXT_GREGS_RCX(%rdi),%rcx
mov UC_MCONTEXT_GREGS_RSP(%rdi),%rsp
/* push the return address on the stack */
mov REG_OFFSET_RIP(%rdi),%rcx
mov UC_MCONTEXT_GREGS_RIP(%rdi),%rcx
push %rcx
mov REG_OFFSET_RCX(%rdi),%rcx
mov REG_OFFSET_RDI(%rdi),%rdi
mov UC_MCONTEXT_GREGS_RCX(%rdi),%rcx
mov UC_MCONTEXT_GREGS_RDI(%rdi),%rdi
retq
#ifdef __linux__

3
src/x86_64/ucontext_i.h
View file

@ -39,3 +39,6 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
#define UC_MCONTEXT_GREGS_RCX 0x98
#define UC_MCONTEXT_GREGS_RSP 0xa0
#define UC_MCONTEXT_GREGS_RIP 0xa8
#define UC_MCONTEXT_FPREGS_PTR 0x1a8
#define UC_MCONTEXT_FPREGS_MEM 0xe0
#define FPREGS_OFFSET_MXCSR 0x18

1
tests/check-namespace.sh.in
View file

@ -121,6 +121,7 @@ check_local_unw_abi () {
match _U${plat}_get_elf_image
match _U${plat}_is_fpreg
match _UL${plat}_dwarf_search_unwind_table
match _U${plat}_setcontext
;;
*)
match _U${plat}_is_fpreg