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x86/alternatives: Provide text_poke_copy_locked()

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The upcoming call thunk patching must hold text_mutex and needs access to
text_poke_copy(), which takes text_mutex.

Provide a _locked postfixed variant to expose the inner workings.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220915111147.159977224@infradead.org
This commit is contained in:
Thomas Gleixner 2022-09-15 13:11:20 +02:00 • committed by Peter Zijlstra
parent 80e4c1cd42
commit fe54d07937
2 changed files with 23 additions and 15 deletions
Download patch file Download diff file Expand all files Collapse all files

1
arch/x86/include/asm/text-patching.h
View file

@ -45,6 +45,7 @@ extern void *text_poke(void *addr, const void *opcode, size_t len);
extern void text_poke_sync(void);
extern void *text_poke_kgdb(void *addr, const void *opcode, size_t len);
extern void *text_poke_copy(void *addr, const void *opcode, size_t len);
extern void *text_poke_copy_locked(void *addr, const void *opcode, size_t len, bool core_ok);
extern void *text_poke_set(void *addr, int c, size_t len);
extern int poke_int3_handler(struct pt_regs *regs);
extern void text_poke_bp(void *addr, const void *opcode, size_t len, const void *emulate);

37
arch/x86/kernel/alternative.c
View file

@ -1236,6 +1236,27 @@ void *text_poke_kgdb(void *addr, const void *opcode, size_t len)
return __text_poke(text_poke_memcpy, addr, opcode, len);
}
void *text_poke_copy_locked(void *addr, const void *opcode, size_t len,
bool core_ok)
{
unsigned long start = (unsigned long)addr;
size_t patched = 0;
if (WARN_ON_ONCE(!core_ok && core_kernel_text(start)))
return NULL;
while (patched < len) {
unsigned long ptr = start + patched;
size_t s;
s = min_t(size_t, PAGE_SIZE * 2 - offset_in_page(ptr), len - patched);
__text_poke(text_poke_memcpy, (void *)ptr, opcode + patched, s);
patched += s;
}
return addr;
}
/**
* text_poke_copy - Copy instructions into (an unused part of) RX memory
* @addr: address to modify
@ -1250,22 +1271,8 @@ void *text_poke_kgdb(void *addr, const void *opcode, size_t len)
*/
void *text_poke_copy(void *addr, const void *opcode, size_t len)
{
unsigned long start = (unsigned long)addr;
size_t patched = 0;
if (WARN_ON_ONCE(core_kernel_text(start)))
return NULL;
mutex_lock(&text_mutex);
while (patched < len) {
unsigned long ptr = start + patched;
size_t s;
s = min_t(size_t, PAGE_SIZE * 2 - offset_in_page(ptr), len - patched);
__text_poke(text_poke_memcpy, (void *)ptr, opcode + patched, s);
patched += s;
}
addr = text_poke_copy_locked(addr, opcode, len, false);
mutex_unlock(&text_mutex);
return addr;
}