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Subject[PATCH/RFC 3/4] kprobes: use probe_kernel_write
From: Heiko Carstens <heiko.carstens@de.ibm.com>

Use proble_kernel_write() to patch the kernel.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
---

arch/s390/kernel/kprobes.c | 31 ++-----------------------------
1 file changed, 2 insertions(+), 29 deletions(-)

diff -urpN linux-2.6/arch/s390/kernel/kprobes.c linux-2.6-patched/arch/s390/kernel/kprobes.c
--- linux-2.6/arch/s390/kernel/kprobes.c 2009-03-24 00:12:14.000000000 +0100
+++ linux-2.6-patched/arch/s390/kernel/kprobes.c 2009-06-02 10:40:05.000000000 +0200
@@ -25,9 +25,9 @@
#include <linux/preempt.h>
#include <linux/stop_machine.h>
#include <linux/kdebug.h>
+#include <linux/uaccess.h>
#include <asm/cacheflush.h>
#include <asm/sections.h>
-#include <asm/uaccess.h>
#include <linux/module.h>

DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
@@ -155,35 +155,8 @@ void __kprobes get_instruction_type(stru
static int __kprobes swap_instruction(void *aref)
{
struct ins_replace_args *args = aref;
- u32 *addr;
- u32 instr;
- int err = -EFAULT;

- /*
- * Text segment is read-only, hence we use stura to bypass dynamic
- * address translation to exchange the instruction. Since stura
- * always operates on four bytes, but we only want to exchange two
- * bytes do some calculations to get things right. In addition we
- * shall not cross any page boundaries (vmalloc area!) when writing
- * the new instruction.
- */
- addr = (u32 *)((unsigned long)args->ptr & -4UL);
- if ((unsigned long)args->ptr & 2)
- instr = ((*addr) & 0xffff0000) | args->new;
- else
- instr = ((*addr) & 0x0000ffff) | args->new << 16;
-
- asm volatile(
- " lra %1,0(%1)\n"
- "0: stura %2,%1\n"
- "1: la %0,0\n"
- "2:\n"
- EX_TABLE(0b,2b)
- : "+d" (err)
- : "a" (addr), "d" (instr)
- : "memory", "cc");
-
- return err;
+ return probe_kernel_write(args->ptr, &args->new, sizeof(args->new));
}

void __kprobes arch_arm_kprobe(struct kprobe *p)
--


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