There's nothing entry-specific about entry_ibpb(). In preparation for
calling it from elsewhere, rename it to __write_ibpb().
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
---
arch/x86/entry/entry.S | 7 ++++---
arch/x86/include/asm/nospec-branch.h | 6 +++---
arch/x86/kernel/cpu/bugs.c | 6 +++---
3 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S
index d3caa31240ed..3a53319988b9 100644
--- a/arch/x86/entry/entry.S
+++ b/arch/x86/entry/entry.S
@@ -17,7 +17,8 @@
.pushsection .noinstr.text, "ax"
-SYM_FUNC_START(entry_ibpb)
+// Clobbers AX, CX, DX
+SYM_FUNC_START(__write_ibpb)
ANNOTATE_NOENDBR
movl $MSR_IA32_PRED_CMD, %ecx
movl $PRED_CMD_IBPB, %eax
@@ -27,9 +28,9 @@ SYM_FUNC_START(entry_ibpb)
/* Make sure IBPB clears return stack preductions too. */
FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_BUG_IBPB_NO_RET
RET
-SYM_FUNC_END(entry_ibpb)
+SYM_FUNC_END(__write_ibpb)
/* For KVM */
-EXPORT_SYMBOL_GPL(entry_ibpb);
+EXPORT_SYMBOL_GPL(__write_ibpb);
.popsection
diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h
index 8a5cc8e70439..bbac79cad04c 100644
--- a/arch/x86/include/asm/nospec-branch.h
+++ b/arch/x86/include/asm/nospec-branch.h
@@ -269,7 +269,7 @@
* typically has NO_MELTDOWN).
*
* While retbleed_untrain_ret() doesn't clobber anything but requires stack,
- * entry_ibpb() will clobber AX, CX, DX.
+ * __write_ibpb() will clobber AX, CX, DX.
*
* As such, this must be placed after every *SWITCH_TO_KERNEL_CR3 at a point
* where we have a stack but before any RET instruction.
@@ -279,7 +279,7 @@
VALIDATE_UNRET_END
CALL_UNTRAIN_RET
ALTERNATIVE_2 "", \
- "call entry_ibpb", \ibpb_feature, \
+ "call __write_ibpb", \ibpb_feature, \
__stringify(\call_depth_insns), X86_FEATURE_CALL_DEPTH
#endif
.endm
@@ -368,7 +368,7 @@ extern void srso_return_thunk(void);
extern void srso_alias_return_thunk(void);
extern void entry_untrain_ret(void);
-extern void entry_ibpb(void);
+extern void __write_ibpb(void);
#ifdef CONFIG_X86_64
extern void clear_bhb_loop(void);
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 4386aa6c69e1..310cb3f7139c 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1142,7 +1142,7 @@ static void __init retbleed_select_mitigation(void)
setup_clear_cpu_cap(X86_FEATURE_RETHUNK);
/*
- * There is no need for RSB filling: entry_ibpb() ensures
+ * There is no need for RSB filling: __write_ibpb() ensures
* all predictions, including the RSB, are invalidated,
* regardless of IBPB implementation.
*/
@@ -2676,7 +2676,7 @@ static void __init srso_select_mitigation(void)
setup_clear_cpu_cap(X86_FEATURE_RETHUNK);
/*
- * There is no need for RSB filling: entry_ibpb() ensures
+ * There is no need for RSB filling: __write_ibpb() ensures
* all predictions, including the RSB, are invalidated,
* regardless of IBPB implementation.
*/
@@ -2701,7 +2701,7 @@ static void __init srso_select_mitigation(void)
srso_mitigation = SRSO_MITIGATION_IBPB_ON_VMEXIT;
/*
- * There is no need for RSB filling: entry_ibpb() ensures
+ * There is no need for RSB filling: __write_ibpb() ensures
* all predictions, including the RSB, are invalidated,
* regardless of IBPB implementation.
*/
--
2.48.1* Josh Poimboeuf <jpoimboe@kernel.org> wrote: > There's nothing entry-specific about entry_ibpb(). In preparation for > calling it from elsewhere, rename it to __write_ibpb(). Minor Git-log hygienic request, could you please mention in such patches what the *new* name is? This title is annoyingly passive-aggressive: x86/bugs: Rename entry_ibpb() Let's make it: x86/bugs: Rename entry_ibpb() to write_ibpb() ... or so. Because the new name is infinitely more important going forward than the old name is ever going to be. :-) Thanks, Ingo
On Wed, Apr 02, 2025 at 09:37:07PM +0200, Ingo Molnar wrote: > > * Josh Poimboeuf <jpoimboe@kernel.org> wrote: > > > There's nothing entry-specific about entry_ibpb(). In preparation for > > calling it from elsewhere, rename it to __write_ibpb(). > > Minor Git-log hygienic request, could you please mention in such > patches what the *new* name is? > > This title is annoyingly passive-aggressive: LOL > x86/bugs: Rename entry_ibpb() > > Let's make it: > > x86/bugs: Rename entry_ibpb() to write_ibpb() > > ... or so. Because the new name is infinitely more important going > forward than the old name is ever going to be. :-) Indeed, thanks. -- Josh
On Wed, Apr 02, 2025 at 11:19:18AM -0700, Josh Poimboeuf wrote:
> There's nothing entry-specific about entry_ibpb(). In preparation for
Not anymore - it was done on entry back then AFAIR.
> calling it from elsewhere, rename it to __write_ibpb().
>
> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
> ---
> arch/x86/entry/entry.S | 7 ++++---
> arch/x86/include/asm/nospec-branch.h | 6 +++---
> arch/x86/kernel/cpu/bugs.c | 6 +++---
> 3 files changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S
> index d3caa31240ed..3a53319988b9 100644
> --- a/arch/x86/entry/entry.S
> +++ b/arch/x86/entry/entry.S
> @@ -17,7 +17,8 @@
>
> .pushsection .noinstr.text, "ax"
>
> -SYM_FUNC_START(entry_ibpb)
> +// Clobbers AX, CX, DX
Why the ugly comment style if the rest of the file is already using the
multiline one...
> +SYM_FUNC_START(__write_ibpb)
... and why the __ ?
> ANNOTATE_NOENDBR
> movl $MSR_IA32_PRED_CMD, %ecx
> movl $PRED_CMD_IBPB, %eax
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
On Wed, Apr 02, 2025 at 08:29:28PM +0200, Borislav Petkov wrote: > On Wed, Apr 02, 2025 at 11:19:18AM -0700, Josh Poimboeuf wrote: > > There's nothing entry-specific about entry_ibpb(). In preparation for > > Not anymore - it was done on entry back then AFAIR. > > > calling it from elsewhere, rename it to __write_ibpb(). > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> > > --- > > arch/x86/entry/entry.S | 7 ++++--- > > arch/x86/include/asm/nospec-branch.h | 6 +++--- > > arch/x86/kernel/cpu/bugs.c | 6 +++--- > > 3 files changed, 10 insertions(+), 9 deletions(-) > > > > diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S > > index d3caa31240ed..3a53319988b9 100644 > > --- a/arch/x86/entry/entry.S > > +++ b/arch/x86/entry/entry.S > > @@ -17,7 +17,8 @@ > > > > .pushsection .noinstr.text, "ax" > > > > -SYM_FUNC_START(entry_ibpb) > > +// Clobbers AX, CX, DX > > Why the ugly comment style if the rest of the file is already using the > multiline one... It helps it stand out more? :-) > > +SYM_FUNC_START(__write_ibpb) > > ... and why the __ ? I was thinking the calling interface is a bit nonstandard. But actually it's fine to call from C as those registers are already caller-saved anyway. So yeah, let's drop the '__'. -- Josh
On Wed, Apr 02, 2025 at 11:44:15AM -0700, Josh Poimboeuf wrote:
> It helps it stand out more? :-)
Please don't.
Someone thought that it is a good idea to start using that // ugliness all of
a sudden.
So we decided we should limit it in tip:
Documentation/process/maintainer-tip.rst
The paragrapn that starts with "Use C++ style, tail comments when documenting
..."
> I was thinking the calling interface is a bit nonstandard. But actually
> it's fine to call from C as those registers are already caller-saved
> anyway. So yeah, let's drop the '__'.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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