linux-kernel - [PATCH 1/4] arm64: insn: Do not disable irqs during patching

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Message-Id: <1470302117-32296-2-git-send-email-mbrugger@suse.com>
Date:	Thu,  4 Aug 2016 11:15:14 +0200
From:	Matthias Brugger <mbrugger@...e.com>
To:	pbonzini@...hat.com, rkrcmar@...hat.com,
	christoffer.dall@...aro.org, marc.zyngier@....com,
	linux@...linux.org.uk, catalin.marinas@....com, will.deacon@....com
Cc:	suzuki.poulose@....com, james.morse@....com,
	david.daney@...ium.com, rrichter@...ium.com, agraf@...e.de,
	mbrugger@...e.com, mark.rutland@....com, lorenzo.pieralisi@....com,
	dave.long@...aro.org, ard.biesheuvel@...aro.org,
	zlim.lnx@...il.com, kvm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] arm64: insn: Do not disable irqs during patching

From: Robert Richter <rrichter@...ium.com>

__aarch64_insn_write() is always called with interrupts enabled. Thus,
there is no need to use an irqsave variant for the spin lock.

This change should also address the fix of:

commit abffa6f3b157 ("arm64: convert patch_lock to raw lock")

We need to enable interrupts to allow cpu sync for code patching
using smp_call_function*().

Signed-off-by: Robert Richter <rrichter@...ium.com>
Signed-off-by: Matthias Brugger <mbrugger@...e.com>
---
 arch/arm64/kernel/insn.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/insn.c b/arch/arm64/kernel/insn.c
index 63f9432..138bd8a 100644
--- a/arch/arm64/kernel/insn.c
+++ b/arch/arm64/kernel/insn.c
@@ -86,7 +86,7 @@ bool aarch64_insn_is_branch_imm(u32 insn)
 		aarch64_insn_is_bcond(insn));
 }
 
-static DEFINE_RAW_SPINLOCK(patch_lock);
+static DEFINE_SPINLOCK(patch_lock);
 
 static void __kprobes *patch_map(void *addr, int fixmap)
 {
@@ -129,16 +129,15 @@ int __kprobes aarch64_insn_read(void *addr, u32 *insnp)
 static int __kprobes __aarch64_insn_write(void *addr, u32 insn)
 {
 	void *waddr = addr;
-	unsigned long flags = 0;
 	int ret;
 
-	raw_spin_lock_irqsave(&patch_lock, flags);
+	spin_lock(&patch_lock);
 	waddr = patch_map(addr, FIX_TEXT_POKE0);
 
 	ret = probe_kernel_write(waddr, &insn, AARCH64_INSN_SIZE);
 
 	patch_unmap(FIX_TEXT_POKE0);
-	raw_spin_unlock_irqrestore(&patch_lock, flags);
+	spin_unlock(&patch_lock);
 
 	return ret;
 }
-- 
2.6.6