Gitweb:
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=602033ed5907a59ce86f709082a35be047743a86
Commit: 602033ed5907a59ce86f709082a35be047743a86
Parent: 07d4e9af109221ab731c5aaf832e89776c64b013
Author: Linus Torvalds <[EMAIL PROTECTED]>
AuthorDate: Thu Jul 26 12:07:21 2007 -0700
Committer: Linus Torvalds <[EMAIL PROTECTED]>
CommitDate: Thu Jul 26 12:07:21 2007 -0700
Revert most of "x86: Fix alternatives and kprobes to remap write-protected
kernel text"
This reverts most of commit 19d36ccdc34f5ed444f8a6af0cbfdb6790eb1177.
The way to DEBUG_RODATA interactions with KPROBES and CPU hotplug is to
just not mark the text as being write-protected in the first place.
Both of those facilities depend on rewriting instructions.
Having "helpful" debug facilities that just cause more problem is not
being helpful. It just adds complexity and bugs. Not worth it.
Reported-by: Rafael J. Wysocki <[EMAIL PROTECTED]>
Cc: Andi Kleen <[EMAIL PROTECTED]>
Cc: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
---
arch/i386/kernel/alternative.c | 14 ++------------
arch/i386/mm/init.c | 14 +++++++++++---
arch/x86_64/mm/init.c | 10 ++++++++++
3 files changed, 23 insertions(+), 15 deletions(-)
diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index c3750c2..c85598a 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -430,22 +430,12 @@ void __init alternative_instructions(void)
* 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)
+void __kprobes text_poke(void *addr, 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);
+ asm("clflush (%0) " :: "r" (addr) : "memory");
}
diff --git a/arch/i386/mm/init.c b/arch/i386/mm/init.c
index 1b1a1e6..4c4809f 100644
--- a/arch/i386/mm/init.c
+++ b/arch/i386/mm/init.c
@@ -800,9 +800,17 @@ void mark_rodata_ro(void)
unsigned long start = PFN_ALIGN(_text);
unsigned long size = PFN_ALIGN(_etext) - start;
- change_page_attr(virt_to_page(start),
- size >> PAGE_SHIFT, PAGE_KERNEL_RX);
- printk("Write protecting the kernel text: %luk\n", size >> 10);
+#ifndef CONFIG_KPROBES
+#ifdef CONFIG_HOTPLUG_CPU
+ /* It must still be possible to apply SMP alternatives. */
+ if (num_possible_cpus() <= 1)
+#endif
+ {
+ change_page_attr(virt_to_page(start),
+ size >> PAGE_SHIFT, PAGE_KERNEL_RX);
+ printk("Write protecting the kernel text: %luk\n", size >> 10);
+ }
+#endif
start += size;
size = (unsigned long)__end_rodata - start;
change_page_attr(virt_to_page(start),
diff --git a/arch/x86_64/mm/init.c b/arch/x86_64/mm/init.c
index 38f5d63..458893b 100644
--- a/arch/x86_64/mm/init.c
+++ b/arch/x86_64/mm/init.c
@@ -600,6 +600,16 @@ void mark_rodata_ro(void)
{
unsigned long start = (unsigned long)_stext, end;
+#ifdef CONFIG_HOTPLUG_CPU
+ /* It must still be possible to apply SMP alternatives. */
+ if (num_possible_cpus() > 1)
+ start = (unsigned long)_etext;
+#endif
+
+#ifdef CONFIG_KPROBES
+ start = (unsigned long)__start_rodata;
+#endif
+
end = (unsigned long)__end_rodata;
start = (start + PAGE_SIZE - 1) & PAGE_MASK;
end &= PAGE_MASK;
-
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