* [PATCH 1/2] x86/speculation: Change STIPB to STIBP
@ 2018-12-05 19:49 Waiman Long
2018-12-05 19:49 ` [PATCH 2/2] x86/speculation: switch_to_cond_stibp on is the likely case Waiman Long
2018-12-06 11:06 ` [tip:x86/pti] x86/speculation: Change misspelled STIPB to STIBP tip-bot for Waiman Long
0 siblings, 2 replies; 7+ messages in thread
From: Waiman Long @ 2018-12-05 19:49 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov
Cc: x86, linux-kernel, Peter Zijlstra, Tim Chen, Josh Poimboeuf, Waiman Long
STIBP stands for Single Thread Indirect Branch Predictors. The acronym,
however, can be easily mis-spelled as STIPB. It is perhaps due to the
presence of another related term - IBPB (Indirect Branch Predictor
Barrier).
Fix the mis-spelling in the code.
Signed-off-by: Waiman Long <longman@redhat.com>
---
arch/x86/kernel/cpu/bugs.c | 6 +++---
arch/x86/kernel/process.h | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 500278f..a68b32c 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -54,7 +54,7 @@
u64 __ro_after_init x86_amd_ls_cfg_base;
u64 __ro_after_init x86_amd_ls_cfg_ssbd_mask;
-/* Control conditional STIPB in switch_to() */
+/* Control conditional STIBP in switch_to() */
DEFINE_STATIC_KEY_FALSE(switch_to_cond_stibp);
/* Control conditional IBPB in switch_mm() */
DEFINE_STATIC_KEY_FALSE(switch_mm_cond_ibpb);
@@ -379,12 +379,12 @@ static void __init spec_v2_user_print_cond(const char *reason, bool secure)
"always-on" : "conditional");
}
- /* If enhanced IBRS is enabled no STIPB required */
+ /* If enhanced IBRS is enabled no STIBP required */
if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
return;
/*
- * If SMT is not possible or STIBP is not available clear the STIPB
+ * If SMT is not possible or STIBP is not available clear the STIBP
* mode.
*/
if (!smt_possible || !boot_cpu_has(X86_FEATURE_STIBP))
diff --git a/arch/x86/kernel/process.h b/arch/x86/kernel/process.h
index 898e97c..320ab97 100644
--- a/arch/x86/kernel/process.h
+++ b/arch/x86/kernel/process.h
@@ -19,7 +19,7 @@ static inline void switch_to_extra(struct task_struct *prev,
if (IS_ENABLED(CONFIG_SMP)) {
/*
* Avoid __switch_to_xtra() invocation when conditional
- * STIPB is disabled and the only different bit is
+ * STIBP is disabled and the only different bit is
* TIF_SPEC_IB. For CONFIG_SMP=n TIF_SPEC_IB is not
* in the TIF_WORK_CTXSW masks.
*/
--
1.8.3.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH 2/2] x86/speculation: switch_to_cond_stibp on is the likely case
2018-12-05 19:49 [PATCH 1/2] x86/speculation: Change STIPB to STIBP Waiman Long
@ 2018-12-05 19:49 ` Waiman Long
2018-12-06 8:41 ` Peter Zijlstra
2018-12-06 11:06 ` [tip:x86/pti] x86/speculation: Change misspelled STIPB to STIBP tip-bot for Waiman Long
1 sibling, 1 reply; 7+ messages in thread
From: Waiman Long @ 2018-12-05 19:49 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Borislav Petkov
Cc: x86, linux-kernel, Peter Zijlstra, Tim Chen, Josh Poimboeuf, Waiman Long
Since conditional STIBP is the default, it should be treated as
the likely case. Changes the use of static_branch_unlikely() to
static_branch_likely() for switch_to_cond_stibp.
Signed-off-by: Waiman Long <longman@redhat.com>
---
arch/x86/kernel/cpu/bugs.c | 2 +-
arch/x86/kernel/process.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index a68b32c..bd11119 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -153,7 +153,7 @@ void __init check_bugs(void)
hostval |= ssbd_tif_to_spec_ctrl(ti->flags);
/* Conditional STIBP enabled? */
- if (static_branch_unlikely(&switch_to_cond_stibp))
+ if (static_branch_likely(&switch_to_cond_stibp))
hostval |= stibp_tif_to_spec_ctrl(ti->flags);
if (hostval != guestval) {
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 7d31192..39a21ae 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -434,7 +434,7 @@ static __always_inline void __speculation_ctrl_update(unsigned long tifp,
* otherwise avoid the MSR write.
*/
if (IS_ENABLED(CONFIG_SMP) &&
- static_branch_unlikely(&switch_to_cond_stibp)) {
+ static_branch_likely(&switch_to_cond_stibp)) {
updmsr |= !!(tif_diff & _TIF_SPEC_IB);
msr |= stibp_tif_to_spec_ctrl(tifn);
}
--
1.8.3.1
^ permalink raw reply related [flat|nested] 7+ messages in thread* Re: [PATCH 2/2] x86/speculation: switch_to_cond_stibp on is the likely case
2018-12-05 19:49 ` [PATCH 2/2] x86/speculation: switch_to_cond_stibp on is the likely case Waiman Long
@ 2018-12-06 8:41 ` Peter Zijlstra
2018-12-06 15:38 ` Waiman Long
0 siblings, 1 reply; 7+ messages in thread
From: Peter Zijlstra @ 2018-12-06 8:41 UTC (permalink / raw)
To: Waiman Long
Cc: Thomas Gleixner, Ingo Molnar, Borislav Petkov, x86, linux-kernel,
Tim Chen, Josh Poimboeuf
On Wed, Dec 05, 2018 at 02:49:28PM -0500, Waiman Long wrote:
> Since conditional STIBP is the default, it should be treated as
> the likely case. Changes the use of static_branch_unlikely() to
> static_branch_likely() for switch_to_cond_stibp.
So now you're making kernels on 'fixed' or unaffected hardware slower.
> Signed-off-by: Waiman Long <longman@redhat.com>
> ---
> arch/x86/kernel/cpu/bugs.c | 2 +-
> arch/x86/kernel/process.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
> index a68b32c..bd11119 100644
> --- a/arch/x86/kernel/cpu/bugs.c
> +++ b/arch/x86/kernel/cpu/bugs.c
> @@ -153,7 +153,7 @@ void __init check_bugs(void)
> hostval |= ssbd_tif_to_spec_ctrl(ti->flags);
>
> /* Conditional STIBP enabled? */
> - if (static_branch_unlikely(&switch_to_cond_stibp))
> + if (static_branch_likely(&switch_to_cond_stibp))
> hostval |= stibp_tif_to_spec_ctrl(ti->flags);
>
> if (hostval != guestval) {
> diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
> index 7d31192..39a21ae 100644
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -434,7 +434,7 @@ static __always_inline void __speculation_ctrl_update(unsigned long tifp,
> * otherwise avoid the MSR write.
> */
> if (IS_ENABLED(CONFIG_SMP) &&
> - static_branch_unlikely(&switch_to_cond_stibp)) {
> + static_branch_likely(&switch_to_cond_stibp)) {
> updmsr |= !!(tif_diff & _TIF_SPEC_IB);
> msr |= stibp_tif_to_spec_ctrl(tifn);
> }
> --
> 1.8.3.1
>
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 2/2] x86/speculation: switch_to_cond_stibp on is the likely case
2018-12-06 8:41 ` Peter Zijlstra
@ 2018-12-06 15:38 ` Waiman Long
2018-12-07 8:52 ` Peter Zijlstra
0 siblings, 1 reply; 7+ messages in thread
From: Waiman Long @ 2018-12-06 15:38 UTC (permalink / raw)
To: Peter Zijlstra
Cc: Thomas Gleixner, Ingo Molnar, Borislav Petkov, x86, linux-kernel,
Tim Chen, Josh Poimboeuf
On 12/06/2018 03:41 AM, Peter Zijlstra wrote:
> On Wed, Dec 05, 2018 at 02:49:28PM -0500, Waiman Long wrote:
>> Since conditional STIBP is the default, it should be treated as
>> the likely case. Changes the use of static_branch_unlikely() to
>> static_branch_likely() for switch_to_cond_stibp.
> So now you're making kernels on 'fixed' or unaffected hardware slower.
Good point.
The reason I sent out this patch is because of the inconsistency in the
use of likely/unlikely hints.
arch/x86/kernel/cpu/bugs.c:156: if
(static_branch_unlikely(&switch_to_cond_stibp))
arch/x86/kernel/process.c:440:
static_branch_unlikely(&switch_to_cond_stibp)) {
arch/x86/kernel/process.h:26: if
(!static_branch_likely(&switch_to_cond_stibp)) {
So if we are aiming to optimize for "fixed" or unaffected hardware,
maybe we should modify the likely hint to unlikely then.
Cheers,
Longman
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 2/2] x86/speculation: switch_to_cond_stibp on is the likely case
2018-12-06 15:38 ` Waiman Long
@ 2018-12-07 8:52 ` Peter Zijlstra
2018-12-07 9:33 ` Thomas Gleixner
0 siblings, 1 reply; 7+ messages in thread
From: Peter Zijlstra @ 2018-12-07 8:52 UTC (permalink / raw)
To: Waiman Long
Cc: Thomas Gleixner, Ingo Molnar, Borislav Petkov, x86, linux-kernel,
Tim Chen, Josh Poimboeuf
On Thu, Dec 06, 2018 at 10:38:00AM -0500, Waiman Long wrote:
> On 12/06/2018 03:41 AM, Peter Zijlstra wrote:
> > On Wed, Dec 05, 2018 at 02:49:28PM -0500, Waiman Long wrote:
> >> Since conditional STIBP is the default, it should be treated as
> >> the likely case. Changes the use of static_branch_unlikely() to
> >> static_branch_likely() for switch_to_cond_stibp.
> > So now you're making kernels on 'fixed' or unaffected hardware slower.
>
> Good point.
>
> The reason I sent out this patch is because of the inconsistency in the
> use of likely/unlikely hints.
>
> arch/x86/kernel/cpu/bugs.c:156: if
> (static_branch_unlikely(&switch_to_cond_stibp))
> arch/x86/kernel/process.c:440:
> static_branch_unlikely(&switch_to_cond_stibp)) {
> arch/x86/kernel/process.h:26: if
> (!static_branch_likely(&switch_to_cond_stibp)) {
>
> So if we are aiming to optimize for "fixed" or unaffected hardware,
> maybe we should modify the likely hint to unlikely then.
Right, I think that makes sense, Thomas?
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: [PATCH 2/2] x86/speculation: switch_to_cond_stibp on is the likely case
2018-12-07 8:52 ` Peter Zijlstra
@ 2018-12-07 9:33 ` Thomas Gleixner
0 siblings, 0 replies; 7+ messages in thread
From: Thomas Gleixner @ 2018-12-07 9:33 UTC (permalink / raw)
To: Peter Zijlstra
Cc: Waiman Long, Ingo Molnar, Borislav Petkov, x86, linux-kernel,
Tim Chen, Josh Poimboeuf
[-- Attachment #1: Type: text/plain, Size: 1192 bytes --]
On Fri, 7 Dec 2018, Peter Zijlstra wrote:
> On Thu, Dec 06, 2018 at 10:38:00AM -0500, Waiman Long wrote:
> > On 12/06/2018 03:41 AM, Peter Zijlstra wrote:
> > > On Wed, Dec 05, 2018 at 02:49:28PM -0500, Waiman Long wrote:
> > >> Since conditional STIBP is the default, it should be treated as
> > >> the likely case. Changes the use of static_branch_unlikely() to
> > >> static_branch_likely() for switch_to_cond_stibp.
> > > So now you're making kernels on 'fixed' or unaffected hardware slower.
> >
> > Good point.
> >
> > The reason I sent out this patch is because of the inconsistency in the
> > use of likely/unlikely hints.
> >
> > arch/x86/kernel/cpu/bugs.c:156: if
> > (static_branch_unlikely(&switch_to_cond_stibp))
> > arch/x86/kernel/process.c:440:
> > static_branch_unlikely(&switch_to_cond_stibp)) {
> > arch/x86/kernel/process.h:26: if
> > (!static_branch_likely(&switch_to_cond_stibp)) {
> >
> > So if we are aiming to optimize for "fixed" or unaffected hardware,
> > maybe we should modify the likely hint to unlikely then.
>
> Right, I think that makes sense, Thomas?
Yeah, I probably got that wrong in some places. Let me look.
Thanks,
Thomas
^ permalink raw reply [flat|nested] 7+ messages in thread
* [tip:x86/pti] x86/speculation: Change misspelled STIPB to STIBP
2018-12-05 19:49 [PATCH 1/2] x86/speculation: Change STIPB to STIBP Waiman Long
2018-12-05 19:49 ` [PATCH 2/2] x86/speculation: switch_to_cond_stibp on is the likely case Waiman Long
@ 2018-12-06 11:06 ` tip-bot for Waiman Long
1 sibling, 0 replies; 7+ messages in thread
From: tip-bot for Waiman Long @ 2018-12-06 11:06 UTC (permalink / raw)
To: linux-tip-commits
Cc: tglx, ak, karahmed, hpa, jkosina, linux-kernel, mingo, longman,
mingo, x86, bp, tim.c.chen, konrad.wilk, peterz, jpoimboe, dwmw
Commit-ID: aa77bfb354c495fc4361199e63fc5765b9e1e783
Gitweb: https://git.kernel.org/tip/aa77bfb354c495fc4361199e63fc5765b9e1e783
Author: Waiman Long <longman@redhat.com>
AuthorDate: Wed, 5 Dec 2018 14:49:27 -0500
Committer: Borislav Petkov <bp@suse.de>
CommitDate: Thu, 6 Dec 2018 11:49:15 +0100
x86/speculation: Change misspelled STIPB to STIBP
STIBP stands for Single Thread Indirect Branch Predictors. The acronym,
however, can be easily mis-spelled as STIPB. It is perhaps due to the
presence of another related term - IBPB (Indirect Branch Predictor
Barrier).
Fix the mis-spelling in the code.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: KarimAllah Ahmed <karahmed@amazon.de>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/1544039368-9009-1-git-send-email-longman@redhat.com
---
arch/x86/kernel/cpu/bugs.c | 6 +++---
arch/x86/kernel/process.h | 2 +-
2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 500278f5308e..a68b32cb845a 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -54,7 +54,7 @@ static u64 __ro_after_init x86_spec_ctrl_mask = SPEC_CTRL_IBRS;
u64 __ro_after_init x86_amd_ls_cfg_base;
u64 __ro_after_init x86_amd_ls_cfg_ssbd_mask;
-/* Control conditional STIPB in switch_to() */
+/* Control conditional STIBP in switch_to() */
DEFINE_STATIC_KEY_FALSE(switch_to_cond_stibp);
/* Control conditional IBPB in switch_mm() */
DEFINE_STATIC_KEY_FALSE(switch_mm_cond_ibpb);
@@ -379,12 +379,12 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
"always-on" : "conditional");
}
- /* If enhanced IBRS is enabled no STIPB required */
+ /* If enhanced IBRS is enabled no STIBP required */
if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
return;
/*
- * If SMT is not possible or STIBP is not available clear the STIPB
+ * If SMT is not possible or STIBP is not available clear the STIBP
* mode.
*/
if (!smt_possible || !boot_cpu_has(X86_FEATURE_STIBP))
diff --git a/arch/x86/kernel/process.h b/arch/x86/kernel/process.h
index 898e97cf6629..320ab978fb1f 100644
--- a/arch/x86/kernel/process.h
+++ b/arch/x86/kernel/process.h
@@ -19,7 +19,7 @@ static inline void switch_to_extra(struct task_struct *prev,
if (IS_ENABLED(CONFIG_SMP)) {
/*
* Avoid __switch_to_xtra() invocation when conditional
- * STIPB is disabled and the only different bit is
+ * STIBP is disabled and the only different bit is
* TIF_SPEC_IB. For CONFIG_SMP=n TIF_SPEC_IB is not
* in the TIF_WORK_CTXSW masks.
*/
^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2018-12-07 9:33 UTC | newest]
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2018-12-05 19:49 [PATCH 1/2] x86/speculation: Change STIPB to STIBP Waiman Long
2018-12-05 19:49 ` [PATCH 2/2] x86/speculation: switch_to_cond_stibp on is the likely case Waiman Long
2018-12-06 8:41 ` Peter Zijlstra
2018-12-06 15:38 ` Waiman Long
2018-12-07 8:52 ` Peter Zijlstra
2018-12-07 9:33 ` Thomas Gleixner
2018-12-06 11:06 ` [tip:x86/pti] x86/speculation: Change misspelled STIPB to STIBP tip-bot for Waiman Long
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