[patch 06/24] Text Edit Lock - Alternative code for x86
Fix a memcpy that should be a text_poke (in apply_alternatives).
Use kernel_wp_save/kernel_wp_restore in text_poke to support DEBUG_RODATA
correctly and so the CPU HOTPLUG special case can be removed.
Add text_poke_early, for alternatives and paravirt boot-time and module load
time patching.
Notes:
- A macro is used instead of an inline function to deal with circular header
include otherwise necessary for read_cr0 and preempt_disable/enable.
Changelog:
- Fix text_set and text_poke alignment check (mixed up bitwise and and or)
- Remove text_set
- Use the new macro INIT_ARRAY() to stop polluting the C files with ({ })
brackets (which breaks some c parsers in editors).
- Export add_nops, so it can be used by others.
- Remove x86 test for "wp_works_ok", it will just be ignored by the architecture
if not supported.
- Document text_poke_early.
- Remove clflush, since it breaks some VIA architectures and is not strictly
necessary.
- Add kerneldoc to text_poke and text_poke_early.
- Remove arg cr0 from kernel_wp_save/restore. Change the macro name for
kernel_wp_disable/enable.
Signed-off-by: Mathieu Desnoyers <[EMAIL PROTECTED]>
CC: Andi Kleen <[EMAIL PROTECTED]>
CC: [EMAIL PROTECTED]
CC: Thomas Gleixner <[EMAIL PROTECTED]>
CC: Ingo Molnar <[EMAIL PROTECTED]>
CC: H. Peter Anvin <[EMAIL PROTECTED]>
---
arch/x86/kernel/alternative.c| 56 ---
include/asm-x86/alternative_32.h | 36 -
include/asm-x86/alternative_64.h | 36 -
3 files changed, 116 insertions(+), 12 deletions(-)
Index: linux-2.6-lttng/arch/x86/kernel/alternative.c
===
--- linux-2.6-lttng.orig/arch/x86/kernel/alternative.c 2007-12-06
10:08:58.0 -0500
+++ linux-2.6-lttng/arch/x86/kernel/alternative.c 2007-12-06
10:08:58.0 -0500
@@ -173,7 +173,7 @@ static const unsigned char*const * find_
#endif /* CONFIG_X86_64 */
/* Use this to add nops to a buffer, then text_poke the whole buffer. */
-static void add_nops(void *insns, unsigned int len)
+void add_nops(void *insns, unsigned int len)
{
const unsigned char *const *noptable = find_nop_table();
@@ -186,6 +186,7 @@ static void add_nops(void *insns, unsign
len -= noplen;
}
}
+EXPORT_SYMBOL_GPL(add_nops);
extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
extern u8 *__smp_locks[], *__smp_locks_end[];
@@ -219,7 +220,7 @@ void apply_alternatives(struct alt_instr
memcpy(insnbuf, a->replacement, a->replacementlen);
add_nops(insnbuf + a->replacementlen,
a->instrlen - a->replacementlen);
- text_poke(instr, insnbuf, a->instrlen);
+ text_poke_early(instr, insnbuf, a->instrlen);
}
}
@@ -234,7 +235,8 @@ static void alternatives_smp_lock(u8 **s
continue;
if (*ptr > text_end)
continue;
- text_poke(*ptr, ((unsigned char []){0xf0}), 1); /* add lock
prefix */
+ /* add lock prefix */
+ text_poke(*ptr, INIT_ARRAY(unsigned char, 0xf0, 1), 1);
};
}
@@ -397,7 +399,7 @@ void apply_paravirt(struct paravirt_patc
/* Pad the rest with nops */
add_nops(insnbuf + used, p->len - used);
- text_poke(p->instr, insnbuf, p->len);
+ text_poke_early(p->instr, insnbuf, p->len);
}
}
extern struct paravirt_patch_site __start_parainstructions[],
@@ -457,18 +459,52 @@ void __init alternative_instructions(voi
#endif
}
-/*
- * Warning:
+/**
+ * text_poke_early - Update instructions on a live kernel at boot time
+ * @addr: address to modify
+ * @opcode: source of the copy
+ * @len: length to copy
+ *
* 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.
+ * 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.
+ * Warning: read_cr0 is modified by paravirt, this is why we have _early
+ * versions. They are not in the __init section because they can be used at
+ * module load time.
*/
-void __kprobes text_poke(void *addr, unsigned char *opcode, int len)
+void *text_poke_early(void *addr, const void *opcode, size_t len)
{
memcpy(addr, opcode, len);
sync_core();
/* Could also do a CLFLUSH here to speed up CPU recovery; but
that causes hangs on some VIA CPUs. */
+ return addr;
}
+
+/**
+ * text_poke -
[patch 06/24] Text Edit Lock - Alternative code for x86
Fix a memcpy that should be a text_poke (in apply_alternatives).
Use kernel_wp_save/kernel_wp_restore in text_poke to support DEBUG_RODATA
correctly and so the CPU HOTPLUG special case can be removed.
Add text_poke_early, for alternatives and paravirt boot-time and module load
time patching.
Notes:
- A macro is used instead of an inline function to deal with circular header
include otherwise necessary for read_cr0 and preempt_disable/enable.
Changelog:
- Fix text_set and text_poke alignment check (mixed up bitwise and and or)
- Remove text_set
- Use the new macro INIT_ARRAY() to stop polluting the C files with ({ })
brackets (which breaks some c parsers in editors).
- Export add_nops, so it can be used by others.
- Remove x86 test for wp_works_ok, it will just be ignored by the architecture
if not supported.
- Document text_poke_early.
- Remove clflush, since it breaks some VIA architectures and is not strictly
necessary.
- Add kerneldoc to text_poke and text_poke_early.
- Remove arg cr0 from kernel_wp_save/restore. Change the macro name for
kernel_wp_disable/enable.
Signed-off-by: Mathieu Desnoyers [EMAIL PROTECTED]
CC: Andi Kleen [EMAIL PROTECTED]
CC: [EMAIL PROTECTED]
CC: Thomas Gleixner [EMAIL PROTECTED]
CC: Ingo Molnar [EMAIL PROTECTED]
CC: H. Peter Anvin [EMAIL PROTECTED]
---
arch/x86/kernel/alternative.c| 56 ---
include/asm-x86/alternative_32.h | 36 -
include/asm-x86/alternative_64.h | 36 -
3 files changed, 116 insertions(+), 12 deletions(-)
Index: linux-2.6-lttng/arch/x86/kernel/alternative.c
===
--- linux-2.6-lttng.orig/arch/x86/kernel/alternative.c 2007-12-06
10:08:58.0 -0500
+++ linux-2.6-lttng/arch/x86/kernel/alternative.c 2007-12-06
10:08:58.0 -0500
@@ -173,7 +173,7 @@ static const unsigned char*const * find_
#endif /* CONFIG_X86_64 */
/* Use this to add nops to a buffer, then text_poke the whole buffer. */
-static void add_nops(void *insns, unsigned int len)
+void add_nops(void *insns, unsigned int len)
{
const unsigned char *const *noptable = find_nop_table();
@@ -186,6 +186,7 @@ static void add_nops(void *insns, unsign
len -= noplen;
}
}
+EXPORT_SYMBOL_GPL(add_nops);
extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
extern u8 *__smp_locks[], *__smp_locks_end[];
@@ -219,7 +220,7 @@ void apply_alternatives(struct alt_instr
memcpy(insnbuf, a-replacement, a-replacementlen);
add_nops(insnbuf + a-replacementlen,
a-instrlen - a-replacementlen);
- text_poke(instr, insnbuf, a-instrlen);
+ text_poke_early(instr, insnbuf, a-instrlen);
}
}
@@ -234,7 +235,8 @@ static void alternatives_smp_lock(u8 **s
continue;
if (*ptr text_end)
continue;
- text_poke(*ptr, ((unsigned char []){0xf0}), 1); /* add lock
prefix */
+ /* add lock prefix */
+ text_poke(*ptr, INIT_ARRAY(unsigned char, 0xf0, 1), 1);
};
}
@@ -397,7 +399,7 @@ void apply_paravirt(struct paravirt_patc
/* Pad the rest with nops */
add_nops(insnbuf + used, p-len - used);
- text_poke(p-instr, insnbuf, p-len);
+ text_poke_early(p-instr, insnbuf, p-len);
}
}
extern struct paravirt_patch_site __start_parainstructions[],
@@ -457,18 +459,52 @@ void __init alternative_instructions(voi
#endif
}
-/*
- * Warning:
+/**
+ * text_poke_early - Update instructions on a live kernel at boot time
+ * @addr: address to modify
+ * @opcode: source of the copy
+ * @len: length to copy
+ *
* 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.
+ * 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.
+ * Warning: read_cr0 is modified by paravirt, this is why we have _early
+ * versions. They are not in the __init section because they can be used at
+ * module load time.
*/
-void __kprobes text_poke(void *addr, unsigned char *opcode, int len)
+void *text_poke_early(void *addr, const void *opcode, size_t len)
{
memcpy(addr, opcode, len);
sync_core();
/* Could also do a CLFLUSH here to speed up CPU recovery; but
that causes hangs on some VIA CPUs. */
+ return addr;
}
+
+/**
+ * text_poke - Update instructions on a
