From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>
Subject: [PATCH v2] x86/alternatives: Let __text_poke() acquire the pte lock with enabled interrupts
Date: Thu, 13 Aug 2020 12:50:26 +0200 [thread overview]
Message-ID: <20200813105026.bvugytmsso6muljw@linutronix.de> (raw)
In-Reply-To: <20200813104707.fxydmk6ctiwjql75@linutronix.de>
The pte lock is never acquired in-IRQ context so it does not require the
interrupts to be disabled.
RT complains here because the spinlock_t must not be acquired with
disabled interrupts.
use_temporary_mm() expects interrupts to be off because it invokes
switch_mm_irqs_off() and uses per-CPU (current active mm) data.
Move the PTE lock handling outside the interrupt disabled region.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
v1…v2: Reword the patch description.
arch/x86/kernel/alternative.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -875,8 +875,6 @@ static void *__text_poke(void *addr, con
*/
BUG_ON(!pages[0] || (cross_page_boundary && !pages[1]));
- local_irq_save(flags);
-
/*
* Map the page without the global bit, as TLB flushing is done with
* flush_tlb_mm_range(), which is intended for non-global PTEs.
@@ -893,6 +891,8 @@ static void *__text_poke(void *addr, con
*/
VM_BUG_ON(!ptep);
+ local_irq_save(flags);
+
pte = mk_pte(pages[0], pgprot);
set_pte_at(poking_mm, poking_addr, ptep, pte);
@@ -942,8 +942,8 @@ static void *__text_poke(void *addr, con
*/
BUG_ON(memcmp(addr, opcode, len));
- pte_unmap_unlock(ptep, ptl);
local_irq_restore(flags);
+ pte_unmap_unlock(ptep, ptl);
return addr;
}
next prev parent reply other threads:[~2020-08-13 10:50 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-06 16:42 [PATCH] x86/alternatives: Let __text_poke() acquire the pte lock with enabled interrupts Sebastian Andrzej Siewior
2020-08-12 14:39 ` Thomas Gleixner
2020-08-13 10:47 ` Sebastian Andrzej Siewior
2020-08-13 10:50 ` Sebastian Andrzej Siewior [this message]
2020-08-13 11:13 ` [PATCH v2] " peterz
2020-08-13 12:15 ` [tip: x86/urgent] x86/alternatives: Acquire pte lock with interrupts enabled tip-bot2 for Sebastian Andrzej Siewior
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