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Groups > linux.kernel > #1268276 > unrolled thread
| Started by | Andy Lutomirski <luto@kernel.org> |
|---|---|
| First post | 2015-11-12 22:10 +0100 |
| Last post | 2015-11-13 15:20 +0100 |
| Articles | 3 — 2 participants |
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[PATCH v3 0/5] x86 entry stuff, maybe for 4.4 Andy Lutomirski <luto@kernel.org> - 2015-11-12 22:10 +0100
[PATCH v3 3/5] x86/asm: Error out if asm/jump_label.h is included inappropriately Andy Lutomirski <luto@kernel.org> - 2015-11-12 22:10 +0100
Re: [PATCH v3 3/5] x86/asm: Error out if asm/jump_label.h is included inappropriately Thomas Gleixner <tglx@linutronix.de> - 2015-11-13 15:20 +0100
| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Date | 2015-11-12 22:10 +0100 |
| Subject | [PATCH v3 0/5] x86 entry stuff, maybe for 4.4 |
| Message-ID | <qu78l-5oc-3@gated-at.bofh.it> |
The first patch is a bit ugly, but it fixes a bug that could affect
lockdep. That bug is very minor and may not be observable at all,
but I don't really want to bet on it.
The other three are intended to fix a performance regression in the
entry rework that Frédéric objected to. They're much later than I'd
like to have sent them for 4.4, but they're kind-of sort-of
regression fixes, so maybe they're still okay. They would certainly
need careful review, though.
I don't have a great benchmark for them. The biggest impact is
likely to be to user page fault latency on CONFIG_CONTEXT_TRACKING=y
kernels (i.e. distro kernels) that don't use context tracking
(i.e. most users).
Changes from v3: Actually send entire series (patch 1 was missing)
Changes from v1:
- CALL_ENTER_FROM_USER_MODE is now CALL_enter_from_user_mode (Ingo)
- STATIC_JUMP_IF_{TRUE,FALSE} now cannot be (mis-)used on non-jump-label
kernels (Thomas)
- Comments are better (Borislav)
This doesn't really address Thomas' objections to the HAVE_JUMP_LABEL stuff,
but it's more robust now, and maybe that's good enough.
Andy Lutomirski (5):
x86/entry/64: Fix irqflag tracing wrt context tracking
context_tracking: Switch to new static_branch API
x86/asm: Error out if asm/jump_label.h is included inappropriately
x86/asm: Add asm macros for static keys/jump labels
x86/entry/64: Bypass enter_from_user_mode on non-context-tracking
boots
arch/x86/entry/calling.h | 15 ++++++++
arch/x86/entry/entry_64.S | 27 +++++++++++----
arch/x86/include/asm/jump_label.h | 63 ++++++++++++++++++++++++++++++----
include/linux/context_tracking_state.h | 4 +--
kernel/context_tracking.c | 4 +--
5 files changed, 95 insertions(+), 18 deletions(-)
--
2.5.0
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| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Date | 2015-11-12 22:10 +0100 |
| Subject | [PATCH v3 3/5] x86/asm: Error out if asm/jump_label.h is included inappropriately |
| Message-ID | <qu7i2-5GE-15@gated-at.bofh.it> |
| In reply to | #1268276 |
Rather than potentially generating incorrect code on a non-HAVE_JUMP_LABEL kernel if someone includes asm/jump_label.h, error out. Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/include/asm/jump_label.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h index 5daeca3d0f9e..96872dc96597 100644 --- a/arch/x86/include/asm/jump_label.h +++ b/arch/x86/include/asm/jump_label.h @@ -1,6 +1,19 @@ #ifndef _ASM_X86_JUMP_LABEL_H #define _ASM_X86_JUMP_LABEL_H +#ifndef HAVE_JUMP_LABEL +/* + * For better or for worse, if jump labels (the gcc extension) are missing, + * then the entire static branch patching infrastructure is compiled out. + * If that happens, the code in here will malfunction. Raise a compiler + * error instead. + * + * In theory, jump labels and the static branch patching infrastructure + * could be decoupled to fix this. + */ +#error asm/jump_label.h included on a non-jump-label kernel +#endif + #ifndef __ASSEMBLY__ #include <linux/stringify.h> -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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| From | Thomas Gleixner <tglx@linutronix.de> |
|---|---|
| Date | 2015-11-13 15:20 +0100 |
| Subject | Re: [PATCH v3 3/5] x86/asm: Error out if asm/jump_label.h is included inappropriately |
| Message-ID | <qunmO-7uR-7@gated-at.bofh.it> |
| In reply to | #1268277 |
On Thu, 12 Nov 2015, Andy Lutomirski wrote: > Rather than potentially generating incorrect code on a > non-HAVE_JUMP_LABEL kernel if someone includes asm/jump_label.h, > error out. > > Signed-off-by: Andy Lutomirski <luto@kernel.org> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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