linux-kernel - [PATCH 5/5] uprobes: Change write_opcode() to use copy

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Message-ID: <20130324182125.GA13327@redhat.com>
Date:	Sun, 24 Mar 2013 19:21:25 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Anton Arapov <anton@...hat.com>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Josh Stone <jistone@...hat.com>,
	Frank Eigler <fche@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	adrian.m.negreanu@...el.com, Torsten.Polle@....de
Subject: [PATCH 5/5] uprobes: Change write_opcode() to use copy_*page()

Change write_opcode() to use copy_highpage() + copy_to_page()
and simplify the code.

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c |   12 ++----------
 1 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 9d943f7..72f03d4 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -232,7 +232,6 @@ static int write_opcode(struct mm_struct *mm, unsigned long vaddr,
 			uprobe_opcode_t opcode)
 {
 	struct page *old_page, *new_page;
-	void *vaddr_old, *vaddr_new;
 	struct vm_area_struct *vma;
 	int ret;
 
@@ -253,15 +252,8 @@ retry:
 
 	__SetPageUptodate(new_page);
 
-	/* copy the page now that we've got it stable */
-	vaddr_old = kmap_atomic(old_page);
-	vaddr_new = kmap_atomic(new_page);
-
-	memcpy(vaddr_new, vaddr_old, PAGE_SIZE);
-	memcpy(vaddr_new + (vaddr & ~PAGE_MASK), &opcode, UPROBE_SWBP_INSN_SIZE);
-
-	kunmap_atomic(vaddr_new);
-	kunmap_atomic(vaddr_old);
+	copy_highpage(new_page, old_page);
+	copy_to_page(new_page, vaddr, &opcode, UPROBE_SWBP_INSN_SIZE);
 
 	ret = anon_vma_prepare(vma);
 	if (ret)
-- 
1.5.5.1

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