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Make libunwind pass C++ exceptions correctly

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When libunwind is linked with a C++ program that throws exceptions,
the exception that's thrown is passed in %rax. However, libc's
setcontext clears %rax, causing problems.

This patch implements a setcontext that doesn't clobber rax.

TBD: Add dwarf CFI annotations

Signed-off-by: Arun Sharma <arun.sharma@google.com>
This commit is contained in:
Arun Sharma 2007-04-05 20:40:41 -06:00 committed by David Mosberger-Tang
parent 55fe524775
commit 31440e9796
3 changed files with 151 additions and 3 deletions
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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", Debug (8, "resuming at ip=%llx via setcontext()\n",
(unsigned long long) c->dwarf.ip); (unsigned long long) c->dwarf.ip);
setcontext (uc); _x86_64_setcontext (uc);
} }
#else #else
# warning Implement me! # warning Implement me!

73
src/x86_64/gen-offsets.c Normal file
View file

@ -0,0 +1,73 @@
#include <ucontext.h>
#include <stdio.h>
#include <stddef.h>
#define REG_OFFSET(reg) (offsetof(struct ucontext, uc_mcontext.gregs[REG_##reg]))
# define REG_R8 0
# define REG_R9 1
# define REG_R10 2
# define REG_R11 3
# define REG_R12 4
# define REG_R13 5
# define REG_R14 6
# define REG_R15 7
# define REG_RDI 8
# define REG_RSI 9
# define REG_RBP 10
# define REG_RBX 11
# define REG_RDX 12
# define REG_RAX 13
# define REG_RCX 14
# define REG_RSP 15
# define REG_RIP 16
char *regs[] = { "RAX",
"RBX",
"RCX",
"RDX",
"RDI",
"RSI",
"RSP",
"RBP",
"R8",
"R9",
"R10",
"R11",
"R12",
"R13",
"R14",
"R15",
"RIP",
};
main()
{
printf("#define REG_OFFSET_%s\t%d\n" , regs[0], REG_OFFSET(RAX));
printf("#define REG_OFFSET_%s\t%d\n" , regs[1], REG_OFFSET(RBX));
printf("#define REG_OFFSET_%s\t%d\n" , regs[2], REG_OFFSET(RCX));
printf("#define REG_OFFSET_%s\t%d\n" , regs[3], REG_OFFSET(RDX));
printf("#define REG_OFFSET_%s\t%d\n" , regs[4], REG_OFFSET(RDI));
printf("#define REG_OFFSET_%s\t%d\n" , regs[5], REG_OFFSET(RSI));
printf("#define REG_OFFSET_%s\t%d\n" , regs[6], REG_OFFSET(RSP));
printf("#define REG_OFFSET_%s\t%d\n" , regs[7], REG_OFFSET(RBP));
printf("#define REG_OFFSET_%s\t%d\n" , regs[8], REG_OFFSET(R8));
printf("#define REG_OFFSET_%s\t%d\n" , regs[9], REG_OFFSET(R9));
printf("#define REG_OFFSET_%s\t%d\n" , regs[10], REG_OFFSET(R10));
printf("#define REG_OFFSET_%s\t%d\n" , regs[11], REG_OFFSET(R11));
printf("#define REG_OFFSET_%s\t%d\n" , regs[12], REG_OFFSET(R12));
printf("#define REG_OFFSET_%s\t%d\n" , regs[13], REG_OFFSET(R13));
printf("#define REG_OFFSET_%s\t%d\n" , regs[14], REG_OFFSET(R14));
printf("#define REG_OFFSET_%s\t%d\n" , regs[15], REG_OFFSET(R15));
printf("#define REG_OFFSET_%s\t%d\n" , regs[15], REG_OFFSET(R15));
printf("#define REG_OFFSET_%s\t%d\n" , regs[15], REG_OFFSET(R15));
printf("#define REG_OFFSET_%s\t%d\n" , regs[16], REG_OFFSET(RIP));
printf("#define REG_OFFSET_FPREGS_PTR\t%d\n" , offsetof(struct ucontext, uc_mcontext.fpregs));
printf("#define FPREG_OFFSET_MXCR\t%d\n" , offsetof(struct _libc_fpstate, mxcsr));
}

79
src/x86_64/setcontext.S
View file

@ -1,4 +1,79 @@
.global _UI_setcontext /* libunwind - a platform-independent unwind library
Copyright (C) 2007 Google, Inc
Contributed by Arun Sharma <arun.sharma@google.com>
_UI_setcontext: 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. */
#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
.global _x86_64_setcontext
_x86_64_setcontext:
/* restore fp state */
mov REG_OFFSET_FPREGS_PTR(%rdi),%r8
fldenv (%r8)
ldmxcsr FPREG_OFFSET_MXCR(%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
/* push the return address on the stack */
mov REG_OFFSET_RIP(%rdi),%rcx
push %rcx
mov REG_OFFSET_RCX(%rdi),%rcx
mov REG_OFFSET_RDI(%rdi),%rdi
retq retq