The following commit has been merged into the x86/alternatives branch of tip:
Commit-ID: af8967158f9ad759a93e8e7a933c10e7cbb01ba2
Gitweb: https://git.kernel.org/tip/af8967158f9ad759a93e8e7a933c10e7cbb01ba2
Author: Andy Lutomirski <luto@kernel.org>
AuthorDate: Wed, 02 Apr 2025 11:45:40 +02:00
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Sat, 12 Apr 2025 10:06:08 +02:00
x86/mm: Opt-in to IRQs-off activate_mm()
We gain nothing by having the core code enable IRQs right before calling
activate_mm() only for us to turn them right back off again in switch_mm().
This will save a few cycles, so execve() should be blazingly fast with this
patch applied!
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/r/20250402094540.3586683-8-mingo@kernel.org
---
arch/x86/Kconfig | 1 +
arch/x86/include/asm/mmu_context.h | 2 +-
2 files changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4b9f378..aeac63b 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -153,6 +153,7 @@ config X86
select ARCH_WANT_HUGETLB_VMEMMAP_PREINIT if X86_64
select ARCH_WANTS_THP_SWAP if X86_64
select ARCH_HAS_PARANOID_L1D_FLUSH
+ select ARCH_WANT_IRQS_OFF_ACTIVATE_MM
select BUILDTIME_TABLE_SORT
select CLKEVT_I8253
select CLOCKSOURCE_WATCHDOG
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 988c117..c511f85 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -190,7 +190,7 @@ extern void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
#define activate_mm(prev, next) \
do { \
paravirt_enter_mmap(next); \
- switch_mm((prev), (next), NULL); \
+ switch_mm_irqs_off((prev), (next), NULL); \
} while (0);
#ifdef CONFIG_X86_32