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Subject[PATCH] [3/3] Fix unwind annotations for 64bit kernel
Date

From Jan Beulich <jbeulich@novell.com>

This is an older patch from Jan Beulich to fix various problems
with the dwarf2 CFI unwind annotations in 64bit entry_64.S/head_64.S
CFI annotations are needed for reliable backtraces with
gdb, systemtap and other unwinders.

[AK: I keep forward porting it to to newer kernels for my own use,
but it should be really just included. So I'm submitting it on Jan's
behalf]

Cc: jbeulich@novell.com
Signed-off-by: Andi Kleen <ak@linux.intel.com>

---
arch/x86/kernel/entry_64.S | 193 +++++++++++++++++++++++----------------------
arch/x86/kernel/head_64.S | 13 +++
2 files changed, 115 insertions(+), 91 deletions(-)

Index: linux-2.6.32-ak/arch/x86/kernel/entry_64.S
===================================================================
--- linux-2.6.32-ak.orig/arch/x86/kernel/entry_64.S
+++ linux-2.6.32-ak/arch/x86/kernel/entry_64.S
@@ -38,6 +38,7 @@
*/

#include <linux/linkage.h>
+#include <linux/stringify.h>
#include <asm/segment.h>
#include <asm/cache.h>
#include <asm/errno.h>
@@ -240,21 +241,21 @@ ENDPROC(native_usergs_sysret64)
/*
* initial frame state for interrupts (and exceptions without error code)
*/
- .macro EMPTY_FRAME start=1 offset=0
- .if \start
+ .macro EMPTY_FRAME offset=0
CFI_STARTPROC simple
CFI_SIGNAL_FRAME
- CFI_DEF_CFA rsp,8+\offset
- .else
- CFI_DEF_CFA_OFFSET 8+\offset
- .endif
+ CFI_DEF_CFA rsp,\offset
.endm

/*
* initial frame state for interrupts (and exceptions without error code)
*/
.macro INTR_FRAME start=1 offset=0
- EMPTY_FRAME \start, SS+8+\offset-RIP
+ .if \start
+ EMPTY_FRAME __stringify(SS+8+\offset-RIP)
+ .else
+ CFI_DEF_CFA_OFFSET SS+8+\offset-RIP
+ .endif
/*CFI_REL_OFFSET ss, SS+\offset-RIP*/
CFI_REL_OFFSET rsp, RSP+\offset-RIP
/*CFI_REL_OFFSET rflags, EFLAGS+\offset-RIP*/
@@ -267,15 +268,16 @@ ENDPROC(native_usergs_sysret64)
* with vector already pushed)
*/
.macro XCPT_FRAME start=1 offset=0
- INTR_FRAME \start, RIP+\offset-ORIG_RAX
- /*CFI_REL_OFFSET orig_rax, ORIG_RAX-ORIG_RAX*/
+ INTR_FRAME \start, __stringify(RIP+\offset-ORIG_RAX)
.endm

/*
* frame that enables calling into C.
*/
.macro PARTIAL_FRAME start=1 offset=0
- XCPT_FRAME \start, ORIG_RAX+\offset-ARGOFFSET
+ .if \start >= 0
+ XCPT_FRAME \start, __stringify(ORIG_RAX+\offset-ARGOFFSET)
+ .endif
CFI_REL_OFFSET rdi, RDI+\offset-ARGOFFSET
CFI_REL_OFFSET rsi, RSI+\offset-ARGOFFSET
CFI_REL_OFFSET rdx, RDX+\offset-ARGOFFSET
@@ -291,7 +293,9 @@ ENDPROC(native_usergs_sysret64)
* frame that enables passing a complete pt_regs to a C function.
*/
.macro DEFAULT_FRAME start=1 offset=0
- PARTIAL_FRAME \start, R11+\offset-R15
+ .if \start >= -1
+ PARTIAL_FRAME \start, __stringify(R11+\offset-R15)
+ .endif
CFI_REL_OFFSET rbx, RBX+\offset
CFI_REL_OFFSET rbp, RBP+\offset
CFI_REL_OFFSET r12, R12+\offset
@@ -302,21 +306,23 @@ ENDPROC(native_usergs_sysret64)

/* save partial stack frame */
ENTRY(save_args)
- XCPT_FRAME
+ XCPT_FRAME offset=__stringify(ORIG_RAX-ARGOFFSET+16)
cld
- movq_cfi rdi, RDI+16-ARGOFFSET
- movq_cfi rsi, RSI+16-ARGOFFSET
- movq_cfi rdx, RDX+16-ARGOFFSET
- movq_cfi rcx, RCX+16-ARGOFFSET
- movq_cfi rax, RAX+16-ARGOFFSET
- movq_cfi r8, R8+16-ARGOFFSET
- movq_cfi r9, R9+16-ARGOFFSET
- movq_cfi r10, R10+16-ARGOFFSET
- movq_cfi r11, R11+16-ARGOFFSET
+ movq %rdi, RDI+16-ARGOFFSET(%rsp)
+ movq %rsi, RSI+16-ARGOFFSET(%rsp)
+ movq %rdx, RDX+16-ARGOFFSET(%rsp)
+ movq %rcx, RCX+16-ARGOFFSET(%rsp)
+ movq_cfi rax, __stringify(RAX+16-ARGOFFSET)
+ movq %r8, R8+16-ARGOFFSET(%rsp)
+ movq %r9, R9+16-ARGOFFSET(%rsp)
+ movq %r10, R10+16-ARGOFFSET(%rsp)
+ movq_cfi r11, __stringify(R11+16-ARGOFFSET)

leaq -ARGOFFSET+16(%rsp),%rdi /* arg1 for handler */
movq_cfi rbp, 8 /* push %rbp */
leaq 8(%rsp), %rbp /* mov %rsp, %ebp */
+ CFI_DEF_CFA_REGISTER rbp
+ CFI_ADJUST_CFA_OFFSET -8
testl $3, CS(%rdi)
je 1f
SWAPGS
@@ -328,11 +334,10 @@ ENTRY(save_args)
*/
1: incl PER_CPU_VAR(irq_count)
jne 2f
- popq_cfi %rax /* move return address... */
+ popq %rax /* move return address... */
mov PER_CPU_VAR(irq_stack_ptr),%rsp
- EMPTY_FRAME 0
- pushq_cfi %rbp /* backlink for unwinder */
- pushq_cfi %rax /* ... to the new stack */
+ pushq %rbp /* backlink for unwinder */
+ pushq %rax /* ... to the new stack */
/*
* We entered an interrupt context - irqs are off:
*/
@@ -342,14 +347,14 @@ ENTRY(save_args)
END(save_args)

ENTRY(save_rest)
- PARTIAL_FRAME 1 REST_SKIP+8
+ CFI_STARTPROC
movq 5*8+16(%rsp), %r11 /* save return address */
- movq_cfi rbx, RBX+16
- movq_cfi rbp, RBP+16
- movq_cfi r12, R12+16
- movq_cfi r13, R13+16
- movq_cfi r14, R14+16
- movq_cfi r15, R15+16
+ movq %rbx, RBX+16(%rsp)
+ movq %rbp, RBP+16(%rsp)
+ movq %r12, R12+16(%rsp)
+ movq %r13, R13+16(%rsp)
+ movq %r14, R14+16(%rsp)
+ movq %r15, R15+16(%rsp)
movq %r11, 8(%rsp) /* return address */
FIXUP_TOP_OF_STACK %r11, 16
ret
@@ -359,23 +364,23 @@ END(save_rest)
/* save complete stack frame */
.pushsection .kprobes.text, "ax"
ENTRY(save_paranoid)
- XCPT_FRAME 1 RDI+8
+ XCPT_FRAME offset=__stringify(ORIG_RAX-R15+8)
cld
- movq_cfi rdi, RDI+8
- movq_cfi rsi, RSI+8
- movq_cfi rdx, RDX+8
- movq_cfi rcx, RCX+8
- movq_cfi rax, RAX+8
- movq_cfi r8, R8+8
- movq_cfi r9, R9+8
- movq_cfi r10, R10+8
- movq_cfi r11, R11+8
- movq_cfi rbx, RBX+8
- movq_cfi rbp, RBP+8
- movq_cfi r12, R12+8
- movq_cfi r13, R13+8
- movq_cfi r14, R14+8
- movq_cfi r15, R15+8
+ movq %rdi, RDI+8(%rsp)
+ movq %rsi, RSI+8(%rsp)
+ movq_cfi rdx, __stringify(RDX+8)
+ movq_cfi rcx, __stringify(RCX+8)
+ movq_cfi rax, __stringify(RAX+8)
+ movq %r8, R8+8(%rsp)
+ movq %r9, R9+8(%rsp)
+ movq %r10, R10+8(%rsp)
+ movq %r11, R11+8(%rsp)
+ movq_cfi rbx, __stringify(RBX+8)
+ movq %rbp, RBP+8(%rsp)
+ movq %r12, R12+8(%rsp)
+ movq %r13, R13+8(%rsp)
+ movq %r14, R14+8(%rsp)
+ movq %r15, R15+8(%rsp)
movl $1,%ebx
movl $MSR_GS_BASE,%ecx
rdmsr
@@ -685,7 +690,7 @@ ENTRY(\label)
subq $REST_SKIP, %rsp
CFI_ADJUST_CFA_OFFSET REST_SKIP
call save_rest
- DEFAULT_FRAME 0 8 /* offset 8: return address */
+ DEFAULT_FRAME -2 8 /* offset 8: return address */
leaq 8(%rsp), \arg /* pt_regs pointer */
call \func
jmp ptregscall_common
@@ -702,12 +707,12 @@ END(\label)
ENTRY(ptregscall_common)
DEFAULT_FRAME 1 8 /* offset 8: return address */
RESTORE_TOP_OF_STACK %r11, 8
- movq_cfi_restore R15+8, r15
- movq_cfi_restore R14+8, r14
- movq_cfi_restore R13+8, r13
- movq_cfi_restore R12+8, r12
- movq_cfi_restore RBP+8, rbp
- movq_cfi_restore RBX+8, rbx
+ movq_cfi_restore __stringify(R15+8), r15
+ movq_cfi_restore __stringify(R14+8), r14
+ movq_cfi_restore __stringify(R13+8), r13
+ movq_cfi_restore __stringify(R12+8), r12
+ movq_cfi_restore __stringify(RBP+8), rbp
+ movq_cfi_restore __stringify(RBX+8), rbx
ret $REST_SKIP /* pop extended registers */
CFI_ENDPROC
END(ptregscall_common)
@@ -796,10 +801,12 @@ END(interrupt)

/* 0(%rsp): ~(interrupt number) */
.macro interrupt func
- subq $10*8, %rsp
- CFI_ADJUST_CFA_OFFSET 10*8
+ subq $ORIG_RAX-ARGOFFSET+8, %rsp
+ CFI_ADJUST_CFA_OFFSET ORIG_RAX-ARGOFFSET+8
call save_args
- PARTIAL_FRAME 0
+ PARTIAL_FRAME -1 8
+ CFI_REL_OFFSET rbp, 0
+ CFI_DEF_CFA_REGISTER rbp
call \func
.endm

@@ -1028,10 +1035,10 @@ ENTRY(\sym)
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
- subq $15*8,%rsp
- CFI_ADJUST_CFA_OFFSET 15*8
+ subq $ORIG_RAX-R15, %rsp
+ CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
call error_entry
- DEFAULT_FRAME 0
+ DEFAULT_FRAME -1
movq %rsp,%rdi /* pt_regs pointer */
xorl %esi,%esi /* no error code */
call \do_sym
@@ -1046,8 +1053,10 @@ ENTRY(\sym)
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq $-1 /* ORIG_RAX: no syscall to restart */
CFI_ADJUST_CFA_OFFSET 8
- subq $15*8, %rsp
+ subq $ORIG_RAX-R15, %rsp
+ CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
call save_paranoid
+ DEFAULT_FRAME -1
TRACE_IRQS_OFF
movq %rsp,%rdi /* pt_regs pointer */
xorl %esi,%esi /* no error code */
@@ -1063,8 +1072,10 @@ ENTRY(\sym)
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq $-1 /* ORIG_RAX: no syscall to restart */
CFI_ADJUST_CFA_OFFSET 8
- subq $15*8, %rsp
+ subq $ORIG_RAX-R15, %rsp
+ CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
call save_paranoid
+ DEFAULT_FRAME -1
TRACE_IRQS_OFF
movq %rsp,%rdi /* pt_regs pointer */
xorl %esi,%esi /* no error code */
@@ -1081,10 +1092,10 @@ END(\sym)
ENTRY(\sym)
XCPT_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
- subq $15*8,%rsp
- CFI_ADJUST_CFA_OFFSET 15*8
+ subq $ORIG_RAX-R15, %rsp
+ CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
call error_entry
- DEFAULT_FRAME 0
+ DEFAULT_FRAME -1
movq %rsp,%rdi /* pt_regs pointer */
movq ORIG_RAX(%rsp),%rsi /* get error code */
movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */
@@ -1099,10 +1110,10 @@ END(\sym)
ENTRY(\sym)
XCPT_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
- subq $15*8,%rsp
- CFI_ADJUST_CFA_OFFSET 15*8
+ subq $ORIG_RAX-R15, %rsp
+ CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
call save_paranoid
- DEFAULT_FRAME 0
+ DEFAULT_FRAME -1
TRACE_IRQS_OFF
movq %rsp,%rdi /* pt_regs pointer */
movq ORIG_RAX(%rsp),%rsi /* get error code */
@@ -1400,7 +1411,7 @@ paranoidzeroentry machine_check *machine

/* ebx: no swapgs flag */
ENTRY(paranoid_exit)
- INTR_FRAME
+ DEFAULT_FRAME
DISABLE_INTERRUPTS(CLBR_NONE)
TRACE_IRQS_OFF
testl %ebx,%ebx /* swapgs needed? */
@@ -1450,25 +1461,24 @@ END(paranoid_exit)
* returns in "no swapgs flag" in %ebx.
*/
ENTRY(error_entry)
- XCPT_FRAME
- CFI_ADJUST_CFA_OFFSET 15*8
+ XCPT_FRAME offset=__stringify(ORIG_RAX-R15+8)
/* oldrax contains error code */
cld
- movq_cfi rdi, RDI+8
- movq_cfi rsi, RSI+8
- movq_cfi rdx, RDX+8
- movq_cfi rcx, RCX+8
- movq_cfi rax, RAX+8
- movq_cfi r8, R8+8
- movq_cfi r9, R9+8
- movq_cfi r10, R10+8
- movq_cfi r11, R11+8
- movq_cfi rbx, RBX+8
- movq_cfi rbp, RBP+8
- movq_cfi r12, R12+8
- movq_cfi r13, R13+8
- movq_cfi r14, R14+8
- movq_cfi r15, R15+8
+ movq %rdi, RDI+8(%rsp)
+ movq %rsi, RSI+8(%rsp)
+ movq %rdx, RDX+8(%rsp)
+ movq %rcx, RCX+8(%rsp)
+ movq %rax, RAX+8(%rsp)
+ movq %r8, R8+8(%rsp)
+ movq %r9, R9+8(%rsp)
+ movq %r10, R10+8(%rsp)
+ movq %r11, R11+8(%rsp)
+ movq_cfi rbx, __stringify(RBX+8)
+ movq %rbp, RBP+8(%rsp)
+ movq %r12, R12+8(%rsp)
+ movq %r13, R13+8(%rsp)
+ movq %r14, R14+8(%rsp)
+ movq %r15, R15+8(%rsp)
xorl %ebx,%ebx
testl $3,CS+8(%rsp)
je error_kernelspace
@@ -1477,7 +1487,6 @@ error_swapgs:
error_sti:
TRACE_IRQS_OFF
ret
- CFI_ENDPROC

/*
* There are two places in the kernel that can potentially fault with
@@ -1487,6 +1496,7 @@ error_sti:
* compat mode. Check for these here too.
*/
error_kernelspace:
+ CFI_REL_OFFSET rcx, RCX+8
incl %ebx
leaq irq_return(%rip),%rcx
cmpq %rcx,RIP+8(%rsp)
@@ -1497,6 +1507,7 @@ error_kernelspace:
cmpq $gs_change,RIP+8(%rsp)
je error_swapgs
jmp error_sti
+ CFI_ENDPROC
END(error_entry)


@@ -1525,10 +1536,10 @@ ENTRY(nmi)
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
pushq_cfi $-1
- subq $15*8, %rsp
- CFI_ADJUST_CFA_OFFSET 15*8
+ subq $ORIG_RAX-R15, %rsp
+ CFI_ADJUST_CFA_OFFSET ORIG_RAX-R15
call save_paranoid
- DEFAULT_FRAME 0
+ DEFAULT_FRAME -1
/* paranoidentry do_nmi, 0; without TRACE_IRQS_OFF */
movq %rsp,%rdi
movq $-1,%rsi
Index: linux-2.6.32-ak/arch/x86/kernel/head_64.S
===================================================================
--- linux-2.6.32-ak.orig/arch/x86/kernel/head_64.S
+++ linux-2.6.32-ak/arch/x86/kernel/head_64.S
@@ -285,6 +285,8 @@ early_idt_handlers:

ENTRY(early_idt_handler)
#ifdef CONFIG_EARLY_PRINTK
+#include <asm/calling.h>
+#include <asm/dwarf2.h>
cmpl $2,early_recursion_flag(%rip)
jz 1f
incl early_recursion_flag(%rip)
@@ -300,6 +302,16 @@ ENTRY(early_idt_handler)
testl $0x27d00,%eax
je 0f
popq %r8 # get error code
+
+ CFI_STARTPROC simple
+ CFI_SIGNAL_FRAME
+ CFI_DEF_CFA rsp, SS+8-RIP
+# CFI_REL_OFFSET ss, SS-RIP
+ CFI_REL_OFFSET rsp, RSP-RIP
+# CFI_REL_OFFSET rflags, EFLAGS-RIP
+# CFI_REL_OFFSET cs, CS-RIP
+ CFI_REL_OFFSET rip, RIP-RIP
+
0: movq 0(%rsp),%rcx # get ip
movq 8(%rsp),%rdx # get cs
xorl %eax,%eax
@@ -313,6 +325,7 @@ ENTRY(early_idt_handler)
movq 0(%rsp),%rsi # get rip again
call __print_symbol
#endif
+ CFI_ENDPROC
#endif /* EARLY_PRINTK */
1: hlt
jmp 1b

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