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i386: Make patching more robust, fix paravirt issue

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Commit 19d36ccdc3 "x86: Fix alternatives
and kprobes to remap write-protected kernel text" uses code which is
being patched for patching.

In particular, paravirt_ops does patching in two stages: first it
calls paravirt_ops.patch, then it fills any remaining instructions
with nop_out().  nop_out calls text_poke() which calls
lookup_address() which calls pgd_val() (aka paravirt_ops.pgd_val):
that call site is one of the places we patch.

If we always do patching as one single call to text_poke(), we only
need make sure we're not patching the memcpy in text_poke itself.
This means the prototype to paravirt_ops.patch needs to change, to
marshal the new code into a buffer rather than patching in place as it
does now.  It also means all patching goes through text_poke(), which
is known to be safe (apply_alternatives is also changed to make a
single patch).

AK: fix compilation on x86-64 (bad rusty!)
AK: fix boot on x86-64 (sigh)
AK: merged with other patches

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andi Kleen
2007-08-10 22:31:03 +02:00
committed by Linus Torvalds
parent d3f3c93469
commit ab144f5ec6
6 changed files with 90 additions and 67 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/asm-i386/paravirt.h
+10 -6
View File
@@ -47,7 +47,8 @@ struct paravirt_ops
* The patch function should return the number of bytes of code
* generated, as we nop pad the rest in generic code.
*/
unsigned (*patch)(u8 type, u16 clobber, void *firstinsn, unsigned len);
unsigned (*patch)(u8 type, u16 clobber, void *insnbuf,
unsigned long addr, unsigned len);
/* Basic arch-specific setup */
void (*arch_setup)(void);
@@ -253,13 +254,16 @@ extern struct paravirt_ops paravirt_ops;
unsigned paravirt_patch_nop(void);
unsigned paravirt_patch_ignore(unsigned len);
unsigned paravirt_patch_call(void *target, u16 tgt_clobbers,
void *site, u16 site_clobbers,
unsigned paravirt_patch_call(void *insnbuf,
const void *target, u16 tgt_clobbers,
unsigned long addr, u16 site_clobbers,
unsigned len);
unsigned paravirt_patch_jmp(void *target, void *site, unsigned len);
unsigned paravirt_patch_default(u8 type, u16 clobbers, void *site, unsigned len);
unsigned paravirt_patch_jmp(const void *target, void *insnbuf,
unsigned long addr, unsigned len);
unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
unsigned long addr, unsigned len);
unsigned paravirt_patch_insns(void *site, unsigned len,
unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
const char *start, const char *end);
int paravirt_disable_iospace(void);