Fix unwind info for sysenter entry point.

Add unwind info for sigreturn entry points.

arch/i386/Makefile

@@ -114,6 +114,15 @@ zdisk bzdisk: vmlinux
 install fdimage fdimage144 fdimage288: vmlinux
 	$(Q)$(MAKE) $(build)=$(boot) BOOTIMAGE=$(BOOTIMAGE) $@
 
+prepare: include/asm-$(ARCH)/asm_offsets.h
+CLEAN_FILES += include/asm-$(ARCH)/asm_offsets.h
+
+arch/$(ARCH)/kernel/asm-offsets.s: include/asm include/linux/version.h \
+				   include/config/MARKER
+
+include/asm-$(ARCH)/asm_offsets.h: arch/$(ARCH)/kernel/asm-offsets.s
+	$(call filechk,gen-asm-offsets)
+
 archclean:
 	$(Q)$(MAKE) $(clean)=arch/i386/boot
 

arch/i386/kernel/asm-offsets.c

+/*
+ * Generate definitions needed by assembly language modules.
+ * This code generates raw asm output which is post-processed
+ * to extract and format the required data.
+ */
+
+#include <linux/signal.h>
+#include <asm/ucontext.h>
+#include "sigframe.h"
+
+#define DEFINE(sym, val) \
+        asm volatile("\n->" #sym " %0 " #val : : "i" (val))
+
+#define BLANK() asm volatile("\n->" : : )
+
+void foo(void)
+{
+	DEFINE(SIGCONTEXT_eax, offsetof (struct sigcontext, eax));
+	DEFINE(SIGCONTEXT_ebx, offsetof (struct sigcontext, ebx));
+	DEFINE(SIGCONTEXT_ecx, offsetof (struct sigcontext, ecx));
+	DEFINE(SIGCONTEXT_edx, offsetof (struct sigcontext, edx));
+	DEFINE(SIGCONTEXT_esi, offsetof (struct sigcontext, esi));
+	DEFINE(SIGCONTEXT_edi, offsetof (struct sigcontext, edi));
+	DEFINE(SIGCONTEXT_ebp, offsetof (struct sigcontext, ebp));
+	DEFINE(SIGCONTEXT_esp, offsetof (struct sigcontext, esp));
+	DEFINE(SIGCONTEXT_eip, offsetof (struct sigcontext, eip));
+	BLANK();
+
+	DEFINE(RT_SIGFRAME_sigcontext,
+	       offsetof (struct rt_sigframe, uc.uc_mcontext));
+}

arch/i386/kernel/sigframe.h

+struct sigframe
+{
+	char *pretcode;
+	int sig;
+	struct sigcontext sc;
+	struct _fpstate fpstate;
+	unsigned long extramask[_NSIG_WORDS-1];
+	char retcode[8];
+};
+
+struct rt_sigframe
+{
+	char *pretcode;
+	int sig;
+	struct siginfo *pinfo;
+	void *puc;
+	struct siginfo info;
+	struct ucontext uc;
+	struct _fpstate fpstate;
+	char retcode[8];
+};

arch/i386/kernel/signal.c

@@ -23,6 +23,7 @@
 #include <asm/ucontext.h>
 #include <asm/uaccess.h>
 #include <asm/i387.h>
+#include "sigframe.h"
 
 #define DEBUG_SIG 0
 
@@ -126,28 +127,6 @@ sys_sigaltstack(const stack_t *uss, stack_t *uoss)
  * Do a signal return; undo the signal stack.
  */
 
-struct sigframe
-{
-	char *pretcode;
-	int sig;
-	struct sigcontext sc;
-	struct _fpstate fpstate;
-	unsigned long extramask[_NSIG_WORDS-1];
-	char retcode[8];
-};
-
-struct rt_sigframe
-{
-	char *pretcode;
-	int sig;
-	struct siginfo *pinfo;
-	void *puc;
-	struct siginfo info;
-	struct ucontext uc;
-	struct _fpstate fpstate;
-	char retcode[8];
-};
-
 static int
 restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *peax)
 {

arch/i386/kernel/vsyscall-sigreturn.S

@@ -7,6 +7,7 @@
  */
 
 #include <asm/unistd.h>
+#include <asm/asm_offsets.h>
 
 
 /* XXX
@@ -18,21 +19,124 @@
 	.globl __kernel_sigreturn
 	.type __kernel_sigreturn,@function
 __kernel_sigreturn:
-.LSTART_kernel_sigreturn:
+.LSTART_sigreturn:
 	popl %eax		/* XXX does this mean it needs unwind info? */
 	movl $__NR_sigreturn, %eax
 	int $0x80
 .LEND_sigreturn:
 	.size __kernel_sigreturn,.-.LSTART_sigreturn
 
-	.text
 	.balign 32
 	.globl __kernel_rt_sigreturn
 	.type __kernel_rt_sigreturn,@function
 __kernel_rt_sigreturn:
-.LSTART_kernel_rt_sigreturn:
+.LSTART_rt_sigreturn:
 	movl $__NR_rt_sigreturn, %eax
 	int $0x80
 .LEND_rt_sigreturn:
 	.size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn
 	.previous
+
+	.section .eh_frame,"a",@progbits
+.LSTARTFRAMEDLSI1:
+	.long .LENDCIEDLSI1-.LSTARTCIEDLSI1
+.LSTARTCIEDLSI1:
+	.long 0			/* CIE ID */
+	.byte 1			/* Version number */
+	.string "zR"		/* NUL-terminated augmentation string */
+	.uleb128 1		/* Code alignment factor */
+	.sleb128 -4		/* Data alignment factor */
+	.byte 8			/* Return address register column */
+	.uleb128 1		/* Augmentation value length */
+	.byte 0x1b		/* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */
+	.byte 0			/* DW_CFA_nop */
+	.align 4
+.LENDCIEDLSI1:
+	.long .LENDFDEDLSI1-.LSTARTFDEDLSI1 /* Length FDE */
+.LSTARTFDEDLSI1:
+	.long .LSTARTFDEDLSI1-.LSTARTFRAMEDLSI1 /* CIE pointer */
+	/* HACK: The dwarf2 unwind routines will subtract 1 from the
+	   return address to get an address in the middle of the
+	   presumed call instruction.  Since we didn't get here via
+	   a call, we need to include the nop before the real start
+	   to make up for it.  */
+	.long .LSTART_sigreturn-1-.	/* PC-relative start address */
+	.long .LEND_sigreturn-.LSTART_sigreturn+1
+	.uleb128 0			/* Augmentation */
+	/* What follows are the instructions for the table generation.
+	   We record the locations of each register saved.  This is
+	   complicated by the fact that the "CFA" is always assumed to
+	   be the value of the stack pointer in the caller.  This means
+	   that we must define the CFA of this body of code to be the
+	   saved value of the stack pointer in the sigcontext.  Which
+	   also means that there is no fixed relation to the other 
+	   saved registers, which means that we must use DW_CFA_expression
+	   to compute their addresses.  It also means that when we 
+	   adjust the stack with the popl, we have to do it all over again.  */
+
+#define do_cfa_expr(offset)						\
+	.byte 0x0f;			/* DW_CFA_def_cfa_expression */	\
+	.uleb128 1f-0f;			/*   length */			\
+0:	.byte 0x74;			/*     DW_OP_breg4 */		\
+	.sleb128 offset;		/*      offset */		\
+	.byte 0x06;			/*     DW_OP_deref */		\
+1:
+
+#define do_expr(regno, offset)						\
+	.byte 0x10;			/* DW_CFA_expression */		\
+	.uleb128 regno;			/*   regno */			\
+	.uleb128 1f-0f;			/*   length */			\
+0:	.byte 0x74;			/*     DW_OP_breg4 */		\
+	.sleb128 offset;		/*       offset */		\
+1:
+
+	do_cfa_expr(SIGCONTEXT_esp+4)
+	do_expr(0, SIGCONTEXT_eax+4)
+	do_expr(1, SIGCONTEXT_ecx+4)
+	do_expr(2, SIGCONTEXT_edx+4)
+	do_expr(3, SIGCONTEXT_ebx+4)
+	do_expr(5, SIGCONTEXT_ebp+4)
+	do_expr(6, SIGCONTEXT_esi+4)
+	do_expr(7, SIGCONTEXT_edi+4)
+	do_expr(8, SIGCONTEXT_eip+4)
+
+	.byte 0x42	/* DW_CFA_advance_loc 2 -- nop; popl eax. */
+
+	do_cfa_expr(SIGCONTEXT_esp)
+	do_expr(0, SIGCONTEXT_eax)
+	do_expr(1, SIGCONTEXT_ecx)
+	do_expr(2, SIGCONTEXT_edx)
+	do_expr(3, SIGCONTEXT_ebx)
+	do_expr(5, SIGCONTEXT_ebp)
+	do_expr(6, SIGCONTEXT_esi)
+	do_expr(7, SIGCONTEXT_edi)
+	do_expr(8, SIGCONTEXT_eip)
+
+	.align 4
+.LENDFDEDLSI1:
+
+	.long .LENDFDEDLSI2-.LSTARTFDEDLSI2 /* Length FDE */
+.LSTARTFDEDLSI2:
+	.long .LSTARTFDEDLSI2-.LSTARTFRAMEDLSI1 /* CIE pointer */
+	/* HACK: See above wrt unwind library assumptions.  */
+	.long .LSTART_rt_sigreturn-1-.	/* PC-relative start address */
+	.long .LEND_rt_sigreturn-.LSTART_rt_sigreturn+1
+	.uleb128 0			/* Augmentation */
+	/* What follows are the instructions for the table generation.
+	   We record the locations of each register saved.  This is
+	   slightly less complicated than the above, since we don't
+	   modify the stack pointer in the process.  */
+
+	do_cfa_expr(RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_esp)
+	do_expr(0, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_eax)
+	do_expr(1, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_ecx)
+	do_expr(2, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_edx)
+	do_expr(3, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_ebx)
+	do_expr(5, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_ebp)
+	do_expr(6, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_esi)
+	do_expr(7, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_edi)
+	do_expr(8, RT_SIGFRAME_sigcontext-4 + SIGCONTEXT_eip)
+
+	.align 4
+.LENDFDEDLSI2:
+	.previous

arch/i386/kernel/vsyscall-sysenter.S

@@ -74,11 +74,13 @@ SYSENTER_RETURN:
 	.long .Lenter_kernel-.Lpush_edx
 	.byte 0x0e		/* DW_CFA_def_cfa_offset */
 	.byte 0x10		/* RA at offset 16 now */
+	.byte 0x85, 0x04	/* DW_CFA_offset %ebp -16 */
 	/* Finally the epilogue.  */
 	.byte 0x04		/* DW_CFA_advance_loc4 */
 	.long .Lpop_ebp-.Lenter_kernel
 	.byte 0x0e		/* DW_CFA_def_cfa_offset */
 	.byte 0x12		/* RA at offset 12 now */
+	.byte 0xc5		/* DW_CFA_restore %ebp */
 	.byte 0x04		/* DW_CFA_advance_loc4 */
 	.long .Lpop_edx-.Lpop_ebp
 	.byte 0x0e		/* DW_CFA_def_cfa_offset */