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[patches] Backport x86/x86_64 unwind fixes
- To: patches@xxxxxxxxxx
- Subject: [patches] Backport x86/x86_64 unwind fixes
- From: "Joseph S. Myers" <joseph@xxxxxxxxxxxxxxxx>
- Date: Sat, 9 Jun 2007 14:50:57 +0000 (UTC)
I've applied this patch to EGLIBC 2.5 branch to backport some fixes to x86
/ x86_64 unwind information. This fixes various GDB test failures on
x86_64.
Index: sysdeps/unix/sysv/linux/i386/clone.S
===================================================================
--- sysdeps/unix/sysv/linux/i386/clone.S (revision 2455)
+++ sysdeps/unix/sysv/linux/i386/clone.S (working copy)
@@ -120,6 +120,9 @@
ret
L(thread_start):
+ cfi_startproc;
+ /* Clearing frame pointer is insufficient, use CFI. */
+ cfi_undefined (eip);
/* Note: %esi is zero. */
movl %esi,%ebp /* terminate the stack frame */
#ifdef RESET_PID
@@ -152,6 +155,7 @@
jmp L(haspid)
.previous
#endif
+ cfi_endproc;
cfi_startproc
PSEUDO_END (BP_SYM (__clone))
Index: sysdeps/unix/sysv/linux/x86_64/ucontext_i.sym
===================================================================
--- sysdeps/unix/sysv/linux/x86_64/ucontext_i.sym (revision 2455)
+++ sysdeps/unix/sysv/linux/x86_64/ucontext_i.sym (working copy)
@@ -18,6 +18,8 @@
oRBX mreg (RBX)
oR8 mreg (R8)
oR9 mreg (R9)
+oR10 mreg (R10)
+oR11 mreg (R11)
oR12 mreg (R12)
oR13 mreg (R13)
oR14 mreg (R14)
@@ -28,6 +30,7 @@
oRAX mreg (RAX)
oRCX mreg (RCX)
oRIP mreg (RIP)
+oEFL mreg (EFL)
oFPREGS mcontext (fpregs)
oSIGMASK ucontext (uc_sigmask)
oFPREGSMEM ucontext (__fpregs_mem)
Index: sysdeps/unix/sysv/linux/x86_64/clone.S
===================================================================
--- sysdeps/unix/sysv/linux/x86_64/clone.S (revision 2455)
+++ sysdeps/unix/sysv/linux/x86_64/clone.S (working copy)
@@ -89,6 +89,9 @@
ret
L(thread_start):
+ cfi_startproc;
+ /* Clearing frame pointer is insufficient, use CFI. */
+ cfi_undefined (rip);
/* Clear the frame pointer. The ABI suggests this be done, to mark
the outermost frame obviously. */
xorl %ebp, %ebp
@@ -113,6 +116,7 @@
/* Call exit with return value from function call. */
movq %rax, %rdi
call HIDDEN_JUMPTARGET (_exit)
+ cfi_endproc;
cfi_startproc;
PSEUDO_END (BP_SYM (__clone))
Index: sysdeps/unix/sysv/linux/x86_64/Makefile
===================================================================
--- sysdeps/unix/sysv/linux/x86_64/Makefile (revision 2455)
+++ sysdeps/unix/sysv/linux/x86_64/Makefile (working copy)
@@ -10,6 +10,6 @@
sysdep_routines += __start_context
endif
-ifeq ($(subdir),stdlib)
+ifeq ($(subdir),csu)
gen-as-const-headers += ucontext_i.sym
endif
Index: sysdeps/unix/sysv/linux/x86_64/sigaction.c
===================================================================
--- sysdeps/unix/sysv/linux/x86_64/sigaction.c (revision 2455)
+++ sysdeps/unix/sysv/linux/x86_64/sigaction.c (working copy)
@@ -33,6 +33,8 @@
translate it here. */
#include <kernel_sigaction.h>
+#include "ucontext_i.h"
+
/* We do not globally define the SA_RESTORER flag so do it here. */
#define SA_RESTORER 0x04000000
@@ -95,18 +97,95 @@
signal handlers work right. Important are both the names
(__restore_rt) and the exact instruction sequence.
If you ever feel the need to make any changes, please notify the
- appropriate GDB maintainer. */
+ appropriate GDB maintainer.
+ The unwind information starts a byte before __restore_rt, so that
+ it is found when unwinding, to get an address the unwinder assumes
+ will be in the middle of a call instruction. See the Linux kernel
+ (the i386 vsyscall, in particular) for an explanation of the complex
+ unwind information used here in order to get the traditional CFA.
+ We do not restore cs - it's only stored as two bytes here so that's
+ a bit tricky. We don't use the gas cfi directives, so that we can
+ reliably add .cfi_signal_frame. */
+
+#define do_cfa_expr \
+ " .byte 0x0f\n" /* DW_CFA_def_cfa_expression */ \
+ " .uleb128 2f-1f\n" /* length */ \
+ "1: .byte 0x77\n" /* DW_OP_breg7 */ \
+ " .sleb128 " CFI_STRINGIFY (oRSP) "\n" \
+ " .byte 0x06\n" /* DW_OP_deref */ \
+ "2:"
+
+#define do_expr(regno, offset) \
+ " .byte 0x10\n" /* DW_CFA_expression */ \
+ " .uleb128 " CFI_STRINGIFY (regno) "\n" \
+ " .uleb128 2f-1f\n" /* length */ \
+ "1: .byte 0x77\n" /* DW_OP_breg7 */ \
+ " .sleb128 " CFI_STRINGIFY (offset) "\n" \
+ "2:"
+
#define RESTORE(name, syscall) RESTORE2 (name, syscall)
# define RESTORE2(name, syscall) \
-asm \
- ( \
- ".align 16\n" \
- CFI_STARTPROC "\n" \
- "__" #name ":\n" \
- " movq $" #syscall ", %rax\n" \
- " syscall\n" \
- CFI_ENDPROC "\n" \
+asm \
+ ( \
+ /* `nop' for debuggers assuming `call' should not disalign the code. */ \
+ " nop\n" \
+ ".align 16\n" \
+ ".LSTART_" #name ":\n" \
+ " .type __" #name ",@function\n" \
+ "__" #name ":\n" \
+ " movq $" #syscall ", %rax\n" \
+ " syscall\n" \
+ ".LEND_" #name ":\n" \
+ ".section .eh_frame,\"a\",@progbits\n" \
+ ".LSTARTFRAME_" #name ":\n" \
+ " .long .LENDCIE_" #name "-.LSTARTCIE_" #name "\n" \
+ ".LSTARTCIE_" #name ":\n" \
+ " .long 0\n" /* CIE ID */ \
+ " .byte 1\n" /* Version number */ \
+ " .string \"zRS\"\n" /* NUL-terminated augmentation string */ \
+ " .uleb128 1\n" /* Code alignment factor */ \
+ " .sleb128 -8\n" /* Data alignment factor */ \
+ " .uleb128 16\n" /* Return address register column (rip) */ \
+ /* Augmentation value length */ \
+ " .uleb128 .LENDAUGMNT_" #name "-.LSTARTAUGMNT_" #name "\n" \
+ ".LSTARTAUGMNT_" #name ":\n" \
+ " .byte 0x1b\n" /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */ \
+ ".LENDAUGMNT_" #name ":\n" \
+ " .align 8\n" \
+ ".LENDCIE_" #name ":\n" \
+ " .long .LENDFDE_" #name "-.LSTARTFDE_" #name "\n" /* FDE len */ \
+ ".LSTARTFDE_" #name ":\n" \
+ " .long .LSTARTFDE_" #name "-.LSTARTFRAME_" #name "\n" /* CIE */ \
+ /* `LSTART_' is subtracted 1 as debuggers assume a `call' here. */ \
+ " .long (.LSTART_" #name "-1)-.\n" /* PC-relative start addr. */ \
+ " .long .LEND_" #name "-(.LSTART_" #name "-1)\n" \
+ " .uleb128 0\n" /* FDE augmentation length */ \
+ do_cfa_expr \
+ do_expr (8 /* r8 */, oR8) \
+ do_expr (9 /* r9 */, oR9) \
+ do_expr (10 /* r10 */, oR10) \
+ do_expr (11 /* r11 */, oR11) \
+ do_expr (12 /* r12 */, oR12) \
+ do_expr (13 /* r13 */, oR13) \
+ do_expr (14 /* r14 */, oR14) \
+ do_expr (15 /* r15 */, oR15) \
+ do_expr (5 /* rdi */, oRDI) \
+ do_expr (4 /* rsi */, oRSI) \
+ do_expr (6 /* rbp */, oRBP) \
+ do_expr (3 /* rbx */, oRBX) \
+ do_expr (1 /* rdx */, oRDX) \
+ do_expr (0 /* rax */, oRAX) \
+ do_expr (2 /* rcx */, oRCX) \
+ do_expr (7 /* rsp */, oRSP) \
+ do_expr (16 /* rip */, oRIP) \
+ /* libgcc-4.1.1 has only `DWARF_FRAME_REGISTERS == 17'. */ \
+ /* do_expr (49 |* rflags *|, oEFL) */ \
+ /* `cs'/`ds'/`fs' are unaligned and a different size. */ \
+ /* gas: Error: register save offset not a multiple of 8 */ \
+ " .align 8\n" \
+ ".LENDFDE_" #name ":\n" \
+ " .previous\n" \
);
/* The return code for realtime-signals. */
RESTORE (restore_rt, __NR_rt_sigreturn)
Index: ChangeLog.eglibc
===================================================================
--- ChangeLog.eglibc (revision 2455)
+++ ChangeLog.eglibc (working copy)
@@ -1,3 +1,26 @@
+2007-06-09 Joseph Myers <joseph@xxxxxxxxxxxxxxxx>
+
+ Backport from FSF mainline:
+
+ 2006-11-30 Jan Kratochvil <jan.kratochvil@xxxxxxxxxx>
+
+ * sysdeps/unix/sysv/linux/i386/clone.S: Provide CFI for the outermost
+ `clone' function to ensure proper unwinding stop of gdb.
+ * sysdeps/unix/sysv/linux/x86_64/clone.S: Likewise.
+
+ 2006-12-01 Jan Kratochvil <jan.kratochvil@xxxxxxxxxx>
+ * sysdeps/unix/sysv/linux/x86_64/sigaction.c: Fix compatibility with
+ libgcc not supporting `rflags' unwinding (register # >= 17).
+
+ 2006-11-29 Daniel Jacobowitz <dan@xxxxxxxxxxxxxxxx>
+ Jakub Jelinek <jakub@xxxxxxxxxx>
+ Jan Kratochvil <jan.kratochvil@xxxxxxxxxx>
+ * sysdeps/unix/sysv/linux/x86_64/sigaction.c (restore_rt): Add correct
+ unwind information.
+ * sysdeps/unix/sysv/linux/x86_64/Makefile: Provide symbols for
+ 'restore_rt' even in the 'signal' directory.
+ * sysdeps/unix/sysv/linux/x86_64/ucontext_i.sym: Extend the regs list.
+
2007-05-26 Jim Blandy <jimb@xxxxxxxxxxxxxxxx>
* Makefile (TAGS): Avoid backslashes in single-quoted strings.
--
Joseph S. Myers
joseph@xxxxxxxxxxxxxxxx