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-rw-r--r--arch/x86/kernel/alternative.c103
1 files changed, 76 insertions, 27 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 5fed98ca0e1f..df4099dc1c68 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -11,6 +11,8 @@
#include <asm/mce.h>
#include <asm/nmi.h>
#include <asm/vsyscall.h>
+#include <asm/cacheflush.h>
+#include <asm/io.h>
#define MAX_PATCH_LEN (255-1)
@@ -177,7 +179,7 @@ static const unsigned char*const * find_nop_table(void)
#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();
@@ -190,6 +192,7 @@ static void add_nops(void *insns, unsigned int len)
len -= noplen;
}
}
+EXPORT_SYMBOL_GPL(add_nops);
extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
extern u8 *__smp_locks[], *__smp_locks_end[];
@@ -205,7 +208,7 @@ void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
struct alt_instr *a;
char insnbuf[MAX_PATCH_LEN];
- DPRINTK("%s: alt table %p -> %p\n", __FUNCTION__, start, end);
+ DPRINTK("%s: alt table %p -> %p\n", __func__, start, end);
for (a = start; a < end; a++) {
u8 *instr = a->instr;
BUG_ON(a->replacementlen > a->instrlen);
@@ -217,13 +220,13 @@ void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
if (instr >= (u8 *)VSYSCALL_START && instr < (u8*)VSYSCALL_END) {
instr = __va(instr - (u8*)VSYSCALL_START + (u8*)__pa_symbol(&__vsyscall_0));
DPRINTK("%s: vsyscall fixup: %p => %p\n",
- __FUNCTION__, a->instr, instr);
+ __func__, a->instr, instr);
}
#endif
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);
}
}
@@ -284,7 +287,6 @@ void alternatives_smp_module_add(struct module *mod, char *name,
void *text, void *text_end)
{
struct smp_alt_module *smp;
- unsigned long flags;
if (noreplace_smp)
return;
@@ -307,42 +309,40 @@ void alternatives_smp_module_add(struct module *mod, char *name,
smp->text = text;
smp->text_end = text_end;
DPRINTK("%s: locks %p -> %p, text %p -> %p, name %s\n",
- __FUNCTION__, smp->locks, smp->locks_end,
+ __func__, smp->locks, smp->locks_end,
smp->text, smp->text_end, smp->name);
- spin_lock_irqsave(&smp_alt, flags);
+ spin_lock(&smp_alt);
list_add_tail(&smp->next, &smp_alt_modules);
if (boot_cpu_has(X86_FEATURE_UP))
alternatives_smp_unlock(smp->locks, smp->locks_end,
smp->text, smp->text_end);
- spin_unlock_irqrestore(&smp_alt, flags);
+ spin_unlock(&smp_alt);
}
void alternatives_smp_module_del(struct module *mod)
{
struct smp_alt_module *item;
- unsigned long flags;
if (smp_alt_once || noreplace_smp)
return;
- spin_lock_irqsave(&smp_alt, flags);
+ spin_lock(&smp_alt);
list_for_each_entry(item, &smp_alt_modules, next) {
if (mod != item->mod)
continue;
list_del(&item->next);
- spin_unlock_irqrestore(&smp_alt, flags);
- DPRINTK("%s: %s\n", __FUNCTION__, item->name);
+ spin_unlock(&smp_alt);
+ DPRINTK("%s: %s\n", __func__, item->name);
kfree(item);
return;
}
- spin_unlock_irqrestore(&smp_alt, flags);
+ spin_unlock(&smp_alt);
}
void alternatives_smp_switch(int smp)
{
struct smp_alt_module *mod;
- unsigned long flags;
#ifdef CONFIG_LOCKDEP
/*
@@ -359,7 +359,7 @@ void alternatives_smp_switch(int smp)
return;
BUG_ON(!smp && (num_online_cpus() > 1));
- spin_lock_irqsave(&smp_alt, flags);
+ spin_lock(&smp_alt);
/*
* Avoid unnecessary switches because it forces JIT based VMs to
@@ -383,7 +383,7 @@ void alternatives_smp_switch(int smp)
mod->text, mod->text_end);
}
smp_mode = smp;
- spin_unlock_irqrestore(&smp_alt, flags);
+ spin_unlock(&smp_alt);
}
#endif
@@ -411,7 +411,7 @@ void apply_paravirt(struct paravirt_patch_site *start,
/* 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[],
@@ -420,8 +420,6 @@ extern struct paravirt_patch_site __start_parainstructions[],
void __init alternative_instructions(void)
{
- unsigned long flags;
-
/* The patching is not fully atomic, so try to avoid local interruptions
that might execute the to be patched code.
Other CPUs are not running. */
@@ -430,7 +428,6 @@ void __init alternative_instructions(void)
stop_mce();
#endif
- local_irq_save(flags);
apply_alternatives(__alt_instructions, __alt_instructions_end);
/* switch to patch-once-at-boottime-only mode and free the
@@ -462,7 +459,6 @@ void __init alternative_instructions(void)
}
#endif
apply_paravirt(__parainstructions, __parainstructions_end);
- local_irq_restore(flags);
if (smp_alt_once)
free_init_pages("SMP alternatives",
@@ -475,18 +471,71 @@ void __init alternative_instructions(void)
#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.
*/
-void __kprobes text_poke(void *addr, unsigned char *opcode, int len)
+void *text_poke_early(void *addr, const void *opcode, size_t len)
{
+ unsigned long flags;
+ local_irq_save(flags);
memcpy(addr, opcode, len);
+ local_irq_restore(flags);
+ 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 live kernel
+ * @addr: address to modify
+ * @opcode: source of the copy
+ * @len: length to copy
+ *
+ * Only atomic text poke/set should be allowed when not doing early patching.
+ * It means the size must be writable atomically and the address must be aligned
+ * in a way that permits an atomic write. It also makes sure we fit on a single
+ * page.
+ */
+void *__kprobes text_poke(void *addr, const void *opcode, size_t len)
+{
+ unsigned long flags;
+ char *vaddr;
+ int nr_pages = 2;
+
+ BUG_ON(len > sizeof(long));
+ BUG_ON((((long)addr + len - 1) & ~(sizeof(long) - 1))
+ - ((long)addr & ~(sizeof(long) - 1)));
+ if (kernel_text_address((unsigned long)addr)) {
+ struct page *pages[2] = { virt_to_page(addr),
+ virt_to_page(addr + PAGE_SIZE) };
+ if (!pages[1])
+ nr_pages = 1;
+ vaddr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
+ BUG_ON(!vaddr);
+ local_irq_save(flags);
+ memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len);
+ local_irq_restore(flags);
+ vunmap(vaddr);
+ } else {
+ /*
+ * modules are in vmalloc'ed memory, always writable.
+ */
+ local_irq_save(flags);
+ memcpy(addr, opcode, len);
+ local_irq_restore(flags);
+ }
sync_core();
/* Could also do a CLFLUSH here to speed up CPU recovery; but
that causes hangs on some VIA CPUs. */
+ return addr;
}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.