* [PATCH] x86-64: relax pvops stub clobber specifications
@ 2017-02-03 9:03 Jan Beulich
2017-03-01 9:46 ` [tip:x86/asm] x86/entry/64: Relax " tip-bot for Jan Beulich
0 siblings, 1 reply; 2+ messages in thread
From: Jan Beulich @ 2017-02-03 9:03 UTC (permalink / raw)
To: mingo, tglx, hpa; +Cc: linux-kernel
Except for the error_exit case, none of the code paths following the
{DIS,EN}ABLE_INTERRUPTS() invocations being modified here make any
assumptions on register values, so all registers can be clobbered
there. In the error_exit case a minor adjustment to register usage
(at once eliminating an instruction) also allows for this to be true.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
arch/x86/entry/entry_64.S | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
--- 4.10-rc6/arch/x86/entry/entry_64.S
+++ 4.10-rc6-x86_64-relax-clobbers/arch/x86/entry/entry_64.S
@@ -212,7 +212,7 @@ entry_SYSCALL_64_fastpath:
* If we see that no exit work is required (which we are required
* to check with IRQs off), then we can go straight to SYSRET64.
*/
- DISABLE_INTERRUPTS(CLBR_NONE)
+ DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
movq PER_CPU_VAR(current_task), %r11
testl $_TIF_ALLWORK_MASK, TASK_TI_flags(%r11)
@@ -233,7 +233,7 @@ entry_SYSCALL_64_fastpath:
* raise(3) will trigger this, for example. IRQs are off.
*/
TRACE_IRQS_ON
- ENABLE_INTERRUPTS(CLBR_NONE)
+ ENABLE_INTERRUPTS(CLBR_ANY)
SAVE_EXTRA_REGS
movq %rsp, %rdi
call syscall_return_slowpath /* returns with IRQs disabled */
@@ -343,7 +343,7 @@ ENTRY(stub_ptregs_64)
* Called from fast path -- disable IRQs again, pop return address
* and jump to slow path
*/
- DISABLE_INTERRUPTS(CLBR_NONE)
+ DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
popq %rax
jmp entry_SYSCALL64_slow_path
@@ -518,7 +518,7 @@ common_interrupt:
interrupt do_IRQ
/* 0(%rsp): old RSP */
ret_from_intr:
- DISABLE_INTERRUPTS(CLBR_NONE)
+ DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
decl PER_CPU_VAR(irq_count)
@@ -1051,7 +1051,7 @@ END(paranoid_entry)
* On entry, ebx is "no swapgs" flag (1: don't need swapgs, 0: need it)
*/
ENTRY(paranoid_exit)
- DISABLE_INTERRUPTS(CLBR_NONE)
+ DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF_DEBUG
testl %ebx, %ebx /* swapgs needed? */
jnz paranoid_exit_no_swapgs
@@ -1156,10 +1156,9 @@ END(error_entry)
* 0: user gsbase is loaded, we need SWAPGS and standard preparation for return to usermode
*/
ENTRY(error_exit)
- movl %ebx, %eax
- DISABLE_INTERRUPTS(CLBR_NONE)
+ DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
- testl %eax, %eax
+ testl %ebx, %ebx
jnz retint_kernel
jmp retint_user
END(error_exit)
^ permalink raw reply [flat|nested] 2+ messages in thread
* [tip:x86/asm] x86/entry/64: Relax pvops stub clobber specifications
2017-02-03 9:03 [PATCH] x86-64: relax pvops stub clobber specifications Jan Beulich
@ 2017-03-01 9:46 ` tip-bot for Jan Beulich
0 siblings, 0 replies; 2+ messages in thread
From: tip-bot for Jan Beulich @ 2017-03-01 9:46 UTC (permalink / raw)
To: linux-tip-commits
Cc: JBeulich, bp, jbeulich, jpoimboe, dvlasenk, hpa, luto, tglx,
linux-kernel, peterz, torvalds, brgerst, mingo
Commit-ID: 2140a9942b84dd4bf559dd1215b8f43c36ece5b5
Gitweb: http://git.kernel.org/tip/2140a9942b84dd4bf559dd1215b8f43c36ece5b5
Author: Jan Beulich <JBeulich@suse.com>
AuthorDate: Fri, 3 Feb 2017 02:03:25 -0700
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 1 Mar 2017 10:16:35 +0100
x86/entry/64: Relax pvops stub clobber specifications
Except for the error_exit case, none of the code paths following the
{DIS,EN}ABLE_INTERRUPTS() invocations being modified here make any
assumptions on register values, so all registers can be clobbered
there. In the error_exit case a minor adjustment to register usage
(at once eliminating an instruction) also allows for this to be true.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/5894556D02000078001366D3@prv-mh.provo.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/entry/entry_64.S | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 044d18e..d2b2a2948 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -212,7 +212,7 @@ entry_SYSCALL_64_fastpath:
* If we see that no exit work is required (which we are required
* to check with IRQs off), then we can go straight to SYSRET64.
*/
- DISABLE_INTERRUPTS(CLBR_NONE)
+ DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
movq PER_CPU_VAR(current_task), %r11
testl $_TIF_ALLWORK_MASK, TASK_TI_flags(%r11)
@@ -233,7 +233,7 @@ entry_SYSCALL_64_fastpath:
* raise(3) will trigger this, for example. IRQs are off.
*/
TRACE_IRQS_ON
- ENABLE_INTERRUPTS(CLBR_NONE)
+ ENABLE_INTERRUPTS(CLBR_ANY)
SAVE_EXTRA_REGS
movq %rsp, %rdi
call syscall_return_slowpath /* returns with IRQs disabled */
@@ -343,7 +343,7 @@ ENTRY(stub_ptregs_64)
* Called from fast path -- disable IRQs again, pop return address
* and jump to slow path
*/
- DISABLE_INTERRUPTS(CLBR_NONE)
+ DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
popq %rax
jmp entry_SYSCALL64_slow_path
@@ -518,7 +518,7 @@ common_interrupt:
interrupt do_IRQ
/* 0(%rsp): old RSP */
ret_from_intr:
- DISABLE_INTERRUPTS(CLBR_NONE)
+ DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
decl PER_CPU_VAR(irq_count)
@@ -1051,7 +1051,7 @@ END(paranoid_entry)
* On entry, ebx is "no swapgs" flag (1: don't need swapgs, 0: need it)
*/
ENTRY(paranoid_exit)
- DISABLE_INTERRUPTS(CLBR_NONE)
+ DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF_DEBUG
testl %ebx, %ebx /* swapgs needed? */
jnz paranoid_exit_no_swapgs
@@ -1156,10 +1156,9 @@ END(error_entry)
* 0: user gsbase is loaded, we need SWAPGS and standard preparation for return to usermode
*/
ENTRY(error_exit)
- movl %ebx, %eax
- DISABLE_INTERRUPTS(CLBR_NONE)
+ DISABLE_INTERRUPTS(CLBR_ANY)
TRACE_IRQS_OFF
- testl %eax, %eax
+ testl %ebx, %ebx
jnz retint_kernel
jmp retint_user
END(error_exit)
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2017-03-01 9:51 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-02-03 9:03 [PATCH] x86-64: relax pvops stub clobber specifications Jan Beulich
2017-03-01 9:46 ` [tip:x86/asm] x86/entry/64: Relax " tip-bot for Jan Beulich
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).