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Date: Thu, 20 Nov 2008 16:04:12 +0100
From: Ingo Molnar <mingo@...e.hu>
To: Alexander van Heukelum <heukelum@...lshack.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Andi Kleen <andi@...stfloor.org>,
"H. Peter Anvin" <hpa@...or.com>,
Jan Beulich <jbeulich@...ell.com>,
Glauber Costa <gcosta@...hat.com>,
Matt Mackall <mpm@...enic.com>,
Thomas Gleixner <tglx@...utronix.de>,
Nick Piggin <nickpiggin@...oo.com.au>,
Cyrill Gorcunov <gorcunov@...il.com>
Subject: Re: [PATCH] x86: clean up after: move entry_64.S register saving
out of the macros
* Alexander van Heukelum <heukelum@...lshack.com> wrote:
> This add-on patch to x86: move entry_64.S register saving out of the
> macros visually cleans up the appearance of the code by introducing
> some basic helper macro's. It also adds some cfi annotations which
> were missing.
>
> Signed-off-by: Alexander van Heukelum <heukelum@...tmail.fm>
> ---
> arch/x86/kernel/entry_64.S | 220 ++++++++++++++++++++++----------------------
> 1 files changed, 112 insertions(+), 108 deletions(-)
>
> Hello Ingo,
>
> This patch improves the CFI-situation in entry_64.S, but restricted
> mostly to the areas touched by "x86: move entry_64.S register saving
> out of the macros". I'm sure there will be some small errors
> somewhere, but it compiles and runs fine.
very nice cleanup! This is exactly what should be done. Applied to
tip/x86/irq.
Note, i did a small rename:
cfi_pushq => pushq_cfi
cfi_popq => popq_cfi
cfi_store => movq_cfi
as the goal is to have the actual source code read mostly as regular
assembly code. The fact that the macro is equivalent to a
default-annotated pushq/popq/movq instruction is much more important
than the fact that it also does CFI annotations.
Also, while cfi_store is correct as well, the usual x86 assembly term
(and instruction used here) is movq.
Find below how the commit ended up looking like.
Thanks,
Ingo
----------------->
>From 250f351f57022f125c19178af1b0335503f1a02d Mon Sep 17 00:00:00 2001
From: Alexander van Heukelum <heukelum@...lshack.com>
Date: Thu, 20 Nov 2008 14:40:11 +0100
Subject: [PATCH] x86: clean up after: move entry_64.S register saving out of the macros
This add-on patch to x86: move entry_64.S register saving out
of the macros visually cleans up the appearance of the code by
introducing some basic helper macro's. It also adds some cfi
annotations which were missing.
Signed-off-by: Alexander van Heukelum <heukelum@...tmail.fm>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
---
arch/x86/kernel/entry_64.S | 220 ++++++++++++++++++++++----------------------
1 files changed, 112 insertions(+), 108 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index 5a12432..6df9d31 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -60,6 +60,23 @@
#define __AUDIT_ARCH_LE 0x40000000
.code64
+/*
+ * Some macro's to hide the most frequently occuring CFI annotations.
+ */
+ .macro pushq_cfi reg
+ pushq \reg
+ CFI_ADJUST_CFA_OFFSET 8
+ .endm
+
+ .macro popq_cfi reg
+ popq \reg
+ CFI_ADJUST_CFA_OFFSET -8
+ .endm
+
+ .macro movq_cfi reg offset=0
+ movq %\reg, \offset(%rsp)
+ CFI_REL_OFFSET \reg, \offset
+ .endm
#ifdef CONFIG_FUNCTION_TRACER
#ifdef CONFIG_DYNAMIC_FTRACE
@@ -213,84 +230,84 @@ ENTRY(native_usergs_sysret64)
CFI_ADJUST_CFA_OFFSET -(6*8)
.endm
- .macro CFI_DEFAULT_STACK start=1
+/*
+ * initial frame state for interrupts (and exceptions without error code)
+ */
+ .macro EMPTY_FRAME start=1 offset=0
.if \start
- CFI_STARTPROC simple
+ CFI_STARTPROC simple
CFI_SIGNAL_FRAME
- CFI_DEF_CFA rsp,SS+8
+ CFI_DEF_CFA rsp,8+\offset
.else
- CFI_DEF_CFA_OFFSET SS+8
+ CFI_DEF_CFA_OFFSET 8+\offset
.endif
- CFI_REL_OFFSET r15,R15
- CFI_REL_OFFSET r14,R14
- CFI_REL_OFFSET r13,R13
- CFI_REL_OFFSET r12,R12
- CFI_REL_OFFSET rbp,RBP
- CFI_REL_OFFSET rbx,RBX
- CFI_REL_OFFSET r11,R11
- CFI_REL_OFFSET r10,R10
- CFI_REL_OFFSET r9,R9
- CFI_REL_OFFSET r8,R8
- CFI_REL_OFFSET rax,RAX
- CFI_REL_OFFSET rcx,RCX
- CFI_REL_OFFSET rdx,RDX
- CFI_REL_OFFSET rsi,RSI
- CFI_REL_OFFSET rdi,RDI
- CFI_REL_OFFSET rip,RIP
- /*CFI_REL_OFFSET cs,CS*/
- /*CFI_REL_OFFSET rflags,EFLAGS*/
- CFI_REL_OFFSET rsp,RSP
- /*CFI_REL_OFFSET ss,SS*/
.endm
/*
- * initial frame state for interrupts and exceptions
+ * initial frame state for interrupts (and exceptions without error code)
*/
- .macro _frame ref
- CFI_STARTPROC simple
- CFI_SIGNAL_FRAME
- CFI_DEF_CFA rsp,SS+8-\ref
- /*CFI_REL_OFFSET ss,SS-\ref*/
- CFI_REL_OFFSET rsp,RSP-\ref
- /*CFI_REL_OFFSET rflags,EFLAGS-\ref*/
- /*CFI_REL_OFFSET cs,CS-\ref*/
- CFI_REL_OFFSET rip,RIP-\ref
+ .macro INTR_FRAME start=1 offset=0
+ EMPTY_FRAME \start, (SS+8-RIP)+\offset
+ /*CFI_REL_OFFSET ss, SS-RIP+\offset*/
+ CFI_REL_OFFSET rsp, RSP-RIP+\offset
+ /*CFI_REL_OFFSET rflags, EFLAGS-RIP+\offset*/
+ /*CFI_REL_OFFSET cs, CS-RIP+\offset*/
+ CFI_REL_OFFSET rip, RIP-RIP+\offset
.endm
/*
- * initial frame state for interrupts (and exceptions without error code)
- */
-#define INTR_FRAME _frame RIP
-/*
* initial frame state for exceptions with error code (and interrupts
* with vector already pushed)
*/
-#define XCPT_FRAME _frame ORIG_RAX
+ .macro XCPT_FRAME start=1 offset=0
+ INTR_FRAME \start, (RIP-ORIG_RAX)+\offset
+ /*CFI_REL_OFFSET orig_rax, ORIG_RAX-ORIG_RAX*/
+ .endm
+
+/*
+ * frame that enables calling into C.
+ */
+ .macro PARTIAL_FRAME start=1 offset=0
+ XCPT_FRAME \start, (ORIG_RAX-ARGOFFSET)+\offset
+ CFI_REL_OFFSET rdi, (RDI-ARGOFFSET)+\offset
+ CFI_REL_OFFSET rsi, (RSI-ARGOFFSET)+\offset
+ CFI_REL_OFFSET rdx, (RDX-ARGOFFSET)+\offset
+ CFI_REL_OFFSET rcx, (RCX-ARGOFFSET)+\offset
+ CFI_REL_OFFSET rax, (RAX-ARGOFFSET)+\offset
+ CFI_REL_OFFSET r8, (R8-ARGOFFSET)+\offset
+ CFI_REL_OFFSET r9, (R9-ARGOFFSET)+\offset
+ CFI_REL_OFFSET r10, (R10-ARGOFFSET)+\offset
+ CFI_REL_OFFSET r11, (R11-ARGOFFSET)+\offset
+ .endm
+
+/*
+ * frame that enables passing a complete pt_regs to a C function.
+ */
+ .macro DEFAULT_FRAME start=1 offset=0
+ PARTIAL_FRAME \start, (R11-R15)+\offset
+ CFI_REL_OFFSET rbx, RBX+\offset
+ CFI_REL_OFFSET rbp, RBP+\offset
+ CFI_REL_OFFSET r12, R12+\offset
+ CFI_REL_OFFSET r13, R13+\offset
+ CFI_REL_OFFSET r14, R14+\offset
+ CFI_REL_OFFSET r15, R15+\offset
+ .endm
/* save partial stack frame */
ENTRY(save_args)
XCPT_FRAME
cld
- movq %rdi, 8*8+16(%rsp)
- CFI_REL_OFFSET rdi, 8*8+16
- movq %rsi, 7*8+16(%rsp)
- CFI_REL_OFFSET rsi, 7*8+16
- movq %rdx, 6*8+16(%rsp)
- CFI_REL_OFFSET rdx, 6*8+16
- movq %rcx, 5*8+16(%rsp)
- CFI_REL_OFFSET rcx, 5*8+16
- movq %rax, 4*8+16(%rsp)
- CFI_REL_OFFSET rax, 4*8+16
- movq %r8, 3*8+16(%rsp)
- CFI_REL_OFFSET r8, 3*8+16
- movq %r9, 2*8+16(%rsp)
- CFI_REL_OFFSET r9, 2*8+16
- movq %r10, 1*8+16(%rsp)
- CFI_REL_OFFSET r10, 1*8+16
- movq %r11, 0*8+16(%rsp)
- CFI_REL_OFFSET r11, 0*8+16
+ movq_cfi rdi, (RDI-ARGOFFSET)+16
+ movq_cfi rsi, (RSI-ARGOFFSET)+16
+ movq_cfi rdx, (RDX-ARGOFFSET)+16
+ movq_cfi rcx, (RCX-ARGOFFSET)+16
+ movq_cfi rax, (RAX-ARGOFFSET)+16
+ movq_cfi r8, (R8-ARGOFFSET)+16
+ movq_cfi r9, (R9-ARGOFFSET)+16
+ movq_cfi r10, (R10-ARGOFFSET)+16
+ movq_cfi r11, (R11-ARGOFFSET)+16
leaq -ARGOFFSET+16(%rsp),%rdi /* arg1 for handler */
- movq %rbp, 8(%rsp) /* push %rbp */
+ movq_cfi rbp, 8 /* push %rbp */
leaq 8(%rsp), %rbp /* mov %rsp, %ebp */
testl $3, CS(%rdi)
je 1f
@@ -303,9 +320,10 @@ ENTRY(save_args)
*/
1: incl %gs:pda_irqcount
jne 2f
- pop %rax /* move return address... */
+ popq_cfi %rax /* move return address... */
mov %gs:pda_irqstackptr,%rsp
- push %rax /* ... to the new stack */
+ EMPTY_FRAME 0
+ pushq_cfi %rax /* ... to the new stack */
/*
* We entered an interrupt context - irqs are off:
*/
@@ -319,7 +337,7 @@ END(save_args)
*/
/* rdi: prev */
ENTRY(ret_from_fork)
- CFI_DEFAULT_STACK
+ DEFAULT_FRAME
push kernel_eflags(%rip)
CFI_ADJUST_CFA_OFFSET 8
popf # reset kernel eflags
@@ -732,6 +750,7 @@ END(interrupt)
subq $10*8, %rsp
CFI_ADJUST_CFA_OFFSET 10*8
call save_args
+ PARTIAL_FRAME 0
call \func
.endm
@@ -949,11 +968,11 @@ END(spurious_interrupt)
.macro zeroentry sym
INTR_FRAME
PARAVIRT_ADJUST_EXCEPTION_FRAME
- pushq $-1 /* ORIG_RAX: no syscall to restart */
- CFI_ADJUST_CFA_OFFSET 8
+ pushq_cfi $-1 /* ORIG_RAX: no syscall to restart */
subq $15*8,%rsp
CFI_ADJUST_CFA_OFFSET 15*8
call error_entry
+ DEFAULT_FRAME 0
movq %rsp,%rdi /* pt_regs pointer */
xorl %esi,%esi /* no error code */
call \sym
@@ -967,6 +986,7 @@ END(spurious_interrupt)
subq $15*8,%rsp
CFI_ADJUST_CFA_OFFSET 15*8
call error_entry
+ DEFAULT_FRAME 0
movq %rsp,%rdi /* pt_regs pointer */
movq ORIG_RAX(%rsp),%rsi /* get error code */
movq $-1,ORIG_RAX(%rsp) /* no syscall to restart */
@@ -1079,40 +1099,25 @@ paranoid_schedule\trace:
* returns in "no swapgs flag" in %ebx.
*/
KPROBE_ENTRY(error_entry)
- _frame RDI
+ XCPT_FRAME
CFI_ADJUST_CFA_OFFSET 15*8
/* oldrax contains error code */
cld
- movq %rdi,14*8+8(%rsp)
- CFI_REL_OFFSET rdi,RDI+8
- movq %rsi,13*8+8(%rsp)
- CFI_REL_OFFSET rsi,RSI+8
- movq %rdx,12*8+8(%rsp)
- CFI_REL_OFFSET rdx,RDX+8
- movq %rcx,11*8+8(%rsp)
- CFI_REL_OFFSET rcx,RCX+8
- movq %rax,10*8+8(%rsp)
- CFI_REL_OFFSET rax,RAX+8
- movq %r8, 9*8+8(%rsp)
- CFI_REL_OFFSET r8,R8+8
- movq %r9, 8*8+8(%rsp)
- CFI_REL_OFFSET r9,R9+8
- movq %r10,7*8+8(%rsp)
- CFI_REL_OFFSET r10,R10+8
- movq %r11,6*8+8(%rsp)
- CFI_REL_OFFSET r11,R11+8
- movq %rbx,5*8+8(%rsp)
- CFI_REL_OFFSET rbx,RBX+8
- movq %rbp,4*8+8(%rsp)
- CFI_REL_OFFSET rbp,RBP+8
- movq %r12,3*8+8(%rsp)
- CFI_REL_OFFSET r12,R12+8
- movq %r13,2*8+8(%rsp)
- CFI_REL_OFFSET r13,R13+8
- movq %r14,1*8+8(%rsp)
- CFI_REL_OFFSET r14,R14+8
- movq %r15,0*8+8(%rsp)
- CFI_REL_OFFSET r15,R15+8
+ 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
xorl %ebx,%ebx
testl $3,CS+8(%rsp)
je error_kernelspace
@@ -1146,7 +1151,7 @@ KPROBE_END(error_entry)
/* ebx: no swapgs flag (1: don't need swapgs, 0: need it) */
KPROBE_ENTRY(error_exit)
- _frame R15
+ DEFAULT_FRAME
movl %ebx,%eax
RESTORE_REST
DISABLE_INTERRUPTS(CLBR_NONE)
@@ -1455,7 +1460,7 @@ ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
see the correct pointer to the pt_regs */
movq %rdi, %rsp # we don't return, adjust the stack frame
CFI_ENDPROC
- CFI_DEFAULT_STACK
+ DEFAULT_FRAME
11: incl %gs:pda_irqcount
movq %rsp,%rbp
CFI_DEF_CFA_REGISTER rbp
@@ -1483,10 +1488,13 @@ END(do_hypervisor_callback)
# with its current contents: any discrepancy means we in category 1.
*/
ENTRY(xen_failsafe_callback)
- framesz = (RIP-0x30) /* workaround buggy gas */
- _frame framesz
- CFI_REL_OFFSET rcx, 0
- CFI_REL_OFFSET r11, 8
+ INTR_FRAME 1 (6*8)
+ /*CFI_REL_OFFSET gs,GS*/
+ /*CFI_REL_OFFSET fs,FS*/
+ /*CFI_REL_OFFSET es,ES*/
+ /*CFI_REL_OFFSET ds,DS*/
+ CFI_REL_OFFSET r11,8
+ CFI_REL_OFFSET rcx,0
movw %ds,%cx
cmpw %cx,0x10(%rsp)
CFI_REMEMBER_STATE
@@ -1507,12 +1515,9 @@ ENTRY(xen_failsafe_callback)
CFI_RESTORE r11
addq $0x30,%rsp
CFI_ADJUST_CFA_OFFSET -0x30
- pushq $0
- CFI_ADJUST_CFA_OFFSET 8
- pushq %r11
- CFI_ADJUST_CFA_OFFSET 8
- pushq %rcx
- CFI_ADJUST_CFA_OFFSET 8
+ pushq_cfi $0 /* RIP */
+ pushq_cfi %r11
+ pushq_cfi %rcx
jmp general_protection
CFI_RESTORE_STATE
1: /* Segment mismatch => Category 1 (Bad segment). Retry the IRET. */
@@ -1522,8 +1527,7 @@ ENTRY(xen_failsafe_callback)
CFI_RESTORE r11
addq $0x30,%rsp
CFI_ADJUST_CFA_OFFSET -0x30
- pushq $0
- CFI_ADJUST_CFA_OFFSET 8
+ pushq_cfi $0
SAVE_ALL
jmp error_exit
CFI_ENDPROC
--
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