From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: linux-kernel@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: [PATCH] x86/alternatives: Let __text_poke() acquire the pte lock with enabled interrupts
Date: Mon, 6 Jul 2020 18:42:15 +0200 [thread overview]
Message-ID: <20200706164215.2502730-1-bigeasy@linutronix.de> (raw)
The pte lock is never acquired from an IRQ-off region 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 local_irq_save() after the the pte lock has been acquired. Move
local_irq_restore() after the pte lock has been released.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
arch/x86/kernel/alternative.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 8fd39ff74a499..7c59a87ebbde8 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -872,8 +872,6 @@ static void *__text_poke(void *addr, const void *opcode, size_t len)
*/
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.
@@ -890,6 +888,8 @@ static void *__text_poke(void *addr, const void *opcode, size_t len)
*/
VM_BUG_ON(!ptep);
+ local_irq_save(flags);
+
pte = mk_pte(pages[0], pgprot);
set_pte_at(poking_mm, poking_addr, ptep, pte);
@@ -939,8 +939,8 @@ static void *__text_poke(void *addr, const void *opcode, size_t len)
*/
BUG_ON(memcmp(addr, opcode, len));
- pte_unmap_unlock(ptep, ptl);
local_irq_restore(flags);
+ pte_unmap_unlock(ptep, ptl);
return addr;
}
--
2.27.0
next reply other threads:[~2020-07-06 16:42 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-06 16:42 Sebastian Andrzej Siewior [this message]
2020-08-12 14:39 ` [PATCH] x86/alternatives: Let __text_poke() acquire the pte lock with enabled interrupts Thomas Gleixner
2020-08-13 10:47 ` Sebastian Andrzej Siewior
2020-08-13 10:50 ` [PATCH v2] " Sebastian Andrzej Siewior
2020-08-13 11:13 ` 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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