text_poke_bp() updates instructions on live kernel on SMP in three steps:
1) add a int3 trap to the address that will be patched
2) update all but the first byte of the patched range
3) replace the first byte (int3) by the first byte of
This patch creates one function for each of these steps.
Signed-off-by: Daniel Bristot de Oliveira
Cc: Thomas Gleixner
Cc: Ingo Molnar
Cc: Borislav Petkov
Cc: "H. Peter Anvin"
Cc: Greg Kroah-Hartman
Cc: Pavel Tatashin
Cc: Masami Hiramatsu
Cc: "Steven Rostedt (VMware)"
Cc: Zhou Chengming
Cc: Jiri Kosina
Cc: Josh Poimboeuf
Cc: "Peter Zijlstra (Intel)"
Cc: Chris von Recklinghausen
Cc: Jason Baron
Cc: Scott Wood
Cc: Marcelo Tosatti
Cc: Clark Williams
Cc: x...@kernel.org
Cc: linux-kernel@vger.kernel.org
---
arch/x86/kernel/alternative.c | 38 +--
1 file changed, 27 insertions(+), 11 deletions(-)
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index ebeac487a20c..6f5ad8587de0 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -767,6 +767,29 @@ int poke_int3_handler(struct pt_regs *regs)
}
+static void text_poke_bp_set_handler(void *addr, void *handler,
+unsigned char int3)
+{
+ bp_int3_handler = handler;
+ bp_int3_addr = (u8 *)addr + sizeof(int3);
+ text_poke(addr, &int3, sizeof(int3));
+}
+
+static void patch_all_but_first_byte(void *addr, const void *opcode,
+size_t len, unsigned char int3)
+{
+ /* patch all but the first byte */
+ text_poke((char *)addr + sizeof(int3),
+ (const char *) opcode + sizeof(int3),
+ len - sizeof(int3));
+}
+
+static void patch_first_byte(void *addr, const void *opcode, unsigned char
int3)
+{
+ /* patch the first byte */
+ text_poke(addr, opcode, sizeof(int3));
+}
+
/**
* text_poke_bp() -- update instructions on live kernel on SMP
* @addr: address to patch
@@ -791,27 +814,21 @@ void *text_poke_bp(void *addr, const void *opcode, size_t
len, void *handler)
{
unsigned char int3 = 0xcc;
- bp_int3_handler = handler;
- bp_int3_addr = (u8 *)addr + sizeof(int3);
- bp_patching_in_progress = true;
-
lockdep_assert_held(&text_mutex);
+ bp_patching_in_progress = true;
/*
* Corresponding read barrier in int3 notifier for making sure the
* in_progress and handler are correctly ordered wrt. patching.
*/
smp_wmb();
- text_poke(addr, &int3, sizeof(int3));
+ text_poke_bp_set_handler(addr, handler, int3);
on_each_cpu(do_sync_core, NULL, 1);
if (len - sizeof(int3) > 0) {
- /* patch all but the first byte */
- text_poke((char *)addr + sizeof(int3),
- (const char *) opcode + sizeof(int3),
- len - sizeof(int3));
+ patch_all_but_first_byte(addr, opcode, len, int3);
/*
* According to Intel, this core syncing is very likely
* not necessary and we'd be safe even without it. But
@@ -820,8 +837,7 @@ void *text_poke_bp(void *addr, const void *opcode, size_t
len, void *handler)
on_each_cpu(do_sync_core, NULL, 1);
}
- /* patch the first byte */
- text_poke(addr, opcode, sizeof(int3));
+ patch_first_byte(addr, opcode, int3);
on_each_cpu(do_sync_core, NULL, 1);
/*
--
2.17.1
