linux-kernel - [PATCH 4.14 33/45] powerpc/lib/code-patching: refactor patch

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Message-Id: <20181011152510.361835278@linuxfoundation.org>
Date:   Thu, 11 Oct 2018 17:40:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Christophe Leroy <christophe.leroy@....fr>,
        Balbir Singh <bsingharora@...il.com>,
        Michael Ellerman <mpe@...erman.id.au>
Subject: [PATCH 4.14 33/45] powerpc/lib/code-patching: refactor patch_instruction()

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christophe Leroy <christophe.leroy@....fr>

commit 8cf4c05712f04a405f0dacebcca8f042b391694a upstream.

patch_instruction() uses almost the same sequence as
__patch_instruction()

This patch refactor it so that patch_instruction() uses
__patch_instruction() instead of duplicating code.

Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
Acked-by: Balbir Singh <bsingharora@...il.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/lib/code-patching.c |   30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -23,19 +23,26 @@
 #include <asm/code-patching.h>
 #include <asm/setup.h>
 
-static int __patch_instruction(unsigned int *addr, unsigned int instr)
+static int __patch_instruction(unsigned int *exec_addr, unsigned int instr,
+			       unsigned int *patch_addr)
 {
 	int err;
 
-	__put_user_size(instr, addr, 4, err);
+	__put_user_size(instr, patch_addr, 4, err);
 	if (err)
 		return err;
 
-	asm ("dcbst 0, %0; sync; icbi 0,%0; sync; isync" :: "r" (addr));
+	asm ("dcbst 0, %0; sync; icbi 0,%1; sync; isync" :: "r" (patch_addr),
+							    "r" (exec_addr));
 
 	return 0;
 }
 
+static int raw_patch_instruction(unsigned int *addr, unsigned int instr)
+{
+	return __patch_instruction(addr, instr, addr);
+}
+
 #ifdef CONFIG_STRICT_KERNEL_RWX
 static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
 
@@ -138,7 +145,7 @@ static inline int unmap_patch_area(unsig
 int patch_instruction(unsigned int *addr, unsigned int instr)
 {
 	int err;
-	unsigned int *dest = NULL;
+	unsigned int *patch_addr = NULL;
 	unsigned long flags;
 	unsigned long text_poke_addr;
 	unsigned long kaddr = (unsigned long)addr;
@@ -149,7 +156,7 @@ int patch_instruction(unsigned int *addr
 	 * to allow patching. We just do the plain old patching
 	 */
 	if (!this_cpu_read(*PTRRELOC(&text_poke_area)))
-		return __patch_instruction(addr, instr);
+		return raw_patch_instruction(addr, instr);
 
 	local_irq_save(flags);
 
@@ -159,17 +166,10 @@ int patch_instruction(unsigned int *addr
 		goto out;
 	}
 
-	dest = (unsigned int *)(text_poke_addr) +
+	patch_addr = (unsigned int *)(text_poke_addr) +
 			((kaddr & ~PAGE_MASK) / sizeof(unsigned int));
 
-	/*
-	 * We use __put_user_size so that we can handle faults while
-	 * writing to dest and return err to handle faults gracefully
-	 */
-	__put_user_size(instr, dest, 4, err);
-	if (!err)
-		asm ("dcbst 0, %0; sync; icbi 0,%0; icbi 0,%1; sync; isync"
-			::"r" (dest), "r"(addr));
+	__patch_instruction(addr, instr, patch_addr);
 
 	err = unmap_patch_area(text_poke_addr);
 	if (err)
@@ -184,7 +184,7 @@ out:
 
 int patch_instruction(unsigned int *addr, unsigned int instr)
 {
-	return __patch_instruction(addr, instr);
+	return raw_patch_instruction(addr, instr);
 }
 
 #endif /* CONFIG_STRICT_KERNEL_RWX */