Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=19d36ccdc34f5ed444f8a6af0cbfdb6790eb1177
Commit: 19d36ccdc34f5ed444f8a6af0cbfdb6790eb1177
Parent: f51c94528a9bc73504928926ca4d791a2b7ddd7c
Author: Andi Kleen [EMAIL PROTECTED]
AuthorDate: Sun Jul 22 11:12:31 2007 +0200
Committer: Linus Torvalds [EMAIL PROTECTED]
CommitDate: Sun Jul 22 11:03:37 2007 -0700
x86: Fix alternatives and kprobes to remap write-protected kernel text
Reenable kprobes and alternative patching when the kernel text is write
protected by DEBUG_RODATA
Add a general utility function to change write protected text. The new
function remaps the code using vmap to write it and takes care of CPU
synchronization. It also does CLFLUSH to make icache recovery faster.
There are some limitations on when the function can be used, see the
comment.
This is a newer version that also changes the paravirt_ops code.
text_poke also supports multi byte patching now.
Contains bug fixes from Zach Amsden and suggestions from Mathieu
Desnoyers.
Cc: Jan Beulich [EMAIL PROTECTED]
Cc: Jeremy Fitzhardinge [EMAIL PROTECTED]
Cc: Mathieu Desnoyers [EMAIL PROTECTED]
Cc: Zach Amsden [EMAIL PROTECTED]
Signed-off-by: Andi Kleen [EMAIL PROTECTED]
Signed-off-by: Linus Torvalds [EMAIL PROTECTED]
---
arch/i386/kernel/alternative.c | 40 -
arch/i386/kernel/kprobes.c |9 ++-
arch/i386/kernel/paravirt.c | 17 ---
arch/i386/mm/init.c | 14 ++--
arch/x86_64/kernel/kprobes.c | 10 ++--
arch/x86_64/mm/init.c| 10 -
arch/x86_64/mm/pageattr.c|2 +-
include/asm-i386/alternative.h |2 +
include/asm-x86_64/alternative.h |2 +
include/asm-x86_64/pgtable.h |2 +
10 files changed, 63 insertions(+), 45 deletions(-)
diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index 0695be5..206ea2c 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -2,8 +2,12 @@
#include linux/sched.h
#include linux/spinlock.h
#include linux/list.h
+#include linux/kprobes.h
+#include linux/mm.h
+#include linux/vmalloc.h
#include asm/alternative.h
#include asm/sections.h
+#include asm/pgtable.h
#ifdef CONFIG_HOTPLUG_CPU
static int smp_alt_once;
@@ -150,7 +154,7 @@ static void nop_out(void *insns, unsigned int len)
unsigned int noplen = len;
if (noplen ASM_NOP_MAX)
noplen = ASM_NOP_MAX;
- memcpy(insns, noptable[noplen], noplen);
+ text_poke(insns, noptable[noplen], noplen);
insns += noplen;
len -= noplen;
}
@@ -202,7 +206,7 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8
*text, u8 *text_end)
continue;
if (*ptr text_end)
continue;
- **ptr = 0xf0; /* lock prefix */
+ text_poke(*ptr, ((unsigned char []){0xf0}), 1); /* add lock
prefix */
};
}
@@ -360,10 +364,6 @@ void apply_paravirt(struct paravirt_patch_site *start,
/* Pad the rest with nops */
nop_out(p-instr + used, p-len - used);
}
-
- /* Sync to be conservative, in case we patched following
-* instructions */
- sync_core();
}
extern struct paravirt_patch_site __start_parainstructions[],
__stop_parainstructions[];
@@ -406,3 +406,31 @@ void __init alternative_instructions(void)
apply_paravirt(__parainstructions, __parainstructions_end);
local_irq_restore(flags);
}
+
+/*
+ * Warning:
+ * When you use this code to patch more than one byte of an instruction
+ * you need to make sure that other CPUs cannot execute this code in parallel.
+ * Also no thread must be currently preempted in the middle of these
instructions.
+ * And on the local CPU you need to be protected again NMI or MCE handlers
+ * seeing an inconsistent instruction while you patch.
+ */
+void __kprobes text_poke(void *oaddr, unsigned char *opcode, int len)
+{
+u8 *addr = oaddr;
+ if (!pte_write(*lookup_address((unsigned long)addr))) {
+ struct page *p[2] = { virt_to_page(addr),
virt_to_page(addr+PAGE_SIZE) };
+ addr = vmap(p, 2, VM_MAP, PAGE_KERNEL);
+ if (!addr)
+ return;
+ addr += ((unsigned long)oaddr) % PAGE_SIZE;
+ }
+ memcpy(addr, opcode, len);
+ sync_core();
+ /* Not strictly needed, but can speed CPU recovery up. Ignore cross
cacheline
+ case. */
+ if (cpu_has_clflush)
+ asm(clflush (%0) :: r (oaddr) : memory);
+ if (addr != oaddr)
+ vunmap(addr);
+}
diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c
index
