Merge branch 'x86/asm' into x86/atomic
Merge reason:
Conflict between LOCK_PREFIX_HERE and relative alternatives
pointers
Resolved Conflicts:
arch/x86/include/asm/alternative.h
arch/x86/kernel/alternative.c
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 80b222e..7023773 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -7,6 +7,8 @@
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/memory.h>
+#include <linux/stop_machine.h>
+#include <linux/slab.h>
#include <asm/alternative.h>
#include <asm/sections.h>
#include <asm/pgtable.h>
@@ -192,7 +194,7 @@
}
extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
-extern u8 *__smp_locks[], *__smp_locks_end[];
+extern s32 __smp_locks[], __smp_locks_end[];
static void *text_poke_early(void *addr, const void *opcode, size_t len);
/* Replace instructions with better alternatives for this CPU type.
@@ -233,39 +235,41 @@
#ifdef CONFIG_SMP
-static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end)
+static void alternatives_smp_lock(const s32 *start, const s32 *end,
+ u8 *text, u8 *text_end)
{
- u8 **ptr;
+ const s32 *poff;
mutex_lock(&text_mutex);
- for (ptr = start; ptr < end; ptr++) {
- if (*ptr < text)
- continue;
- if (*ptr > text_end)
+ for (poff = start; poff < end; poff++) {
+ u8 *ptr = (u8 *)poff + *poff;
+
+ if (!*poff || ptr < text || ptr >= text_end)
continue;
/* turn DS segment override prefix into lock prefix */
- if (**ptr == 0x3e)
- text_poke(*ptr, ((unsigned char []){0xf0}), 1);
+ if (*ptr == 0x3e)
+ text_poke(ptr, ((unsigned char []){0xf0}), 1);
};
mutex_unlock(&text_mutex);
}
-static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end)
+static void alternatives_smp_unlock(const s32 *start, const s32 *end,
+ u8 *text, u8 *text_end)
{
- u8 **ptr;
+ const s32 *poff;
if (noreplace_smp)
return;
mutex_lock(&text_mutex);
- for (ptr = start; ptr < end; ptr++) {
- if (*ptr < text)
- continue;
- if (*ptr > text_end)
+ for (poff = start; poff < end; poff++) {
+ u8 *ptr = (u8 *)poff + *poff;
+
+ if (!*poff || ptr < text || ptr >= text_end)
continue;
/* turn lock prefix into DS segment override prefix */
- if (**ptr == 0xf0)
- text_poke(*ptr, ((unsigned char []){0x3E}), 1);
+ if (*ptr == 0xf0)
+ text_poke(ptr, ((unsigned char []){0x3E}), 1);
};
mutex_unlock(&text_mutex);
}
@@ -276,8 +280,8 @@
char *name;
/* ptrs to lock prefixes */
- u8 **locks;
- u8 **locks_end;
+ const s32 *locks;
+ const s32 *locks_end;
/* .text segment, needed to avoid patching init code ;) */
u8 *text;
@@ -394,6 +398,27 @@
mutex_unlock(&smp_alt);
}
+/* Return 1 if the address range is reserved for smp-alternatives */
+int alternatives_text_reserved(void *start, void *end)
+{
+ struct smp_alt_module *mod;
+ const s32 *poff;
+ u8 *text_start = start;
+ u8 *text_end = end;
+
+ list_for_each_entry(mod, &smp_alt_modules, next) {
+ if (mod->text > text_end || mod->text_end < text_start)
+ continue;
+ for (poff = mod->locks; poff < mod->locks_end; poff++) {
+ const u8 *ptr = (const u8 *)poff + *poff;
+
+ if (text_start <= ptr && text_end > ptr)
+ return 1;
+ }
+ }
+
+ return 0;
+}
#endif
#ifdef CONFIG_PARAVIRT
@@ -556,3 +581,62 @@
local_irq_restore(flags);
return addr;
}
+
+/*
+ * Cross-modifying kernel text with stop_machine().
+ * This code originally comes from immediate value.
+ */
+static atomic_t stop_machine_first;
+static int wrote_text;
+
+struct text_poke_params {
+ void *addr;
+ const void *opcode;
+ size_t len;
+};
+
+static int __kprobes stop_machine_text_poke(void *data)
+{
+ struct text_poke_params *tpp = data;
+
+ if (atomic_dec_and_test(&stop_machine_first)) {
+ text_poke(tpp->addr, tpp->opcode, tpp->len);
+ smp_wmb(); /* Make sure other cpus see that this has run */
+ wrote_text = 1;
+ } else {
+ while (!wrote_text)
+ cpu_relax();
+ smp_mb(); /* Load wrote_text before following execution */
+ }
+
+ flush_icache_range((unsigned long)tpp->addr,
+ (unsigned long)tpp->addr + tpp->len);
+ return 0;
+}
+
+/**
+ * text_poke_smp - Update instructions on a live kernel on SMP
+ * @addr: address to modify
+ * @opcode: source of the copy
+ * @len: length to copy
+ *
+ * Modify multi-byte instruction by using stop_machine() on SMP. This allows
+ * user to poke/set multi-byte text on SMP. Only non-NMI/MCE code modifying
+ * should be allowed, since stop_machine() does _not_ protect code against
+ * NMI and MCE.
+ *
+ * Note: Must be called under get_online_cpus() and text_mutex.
+ */
+void *__kprobes text_poke_smp(void *addr, const void *opcode, size_t len)
+{
+ struct text_poke_params tpp;
+
+ tpp.addr = addr;
+ tpp.opcode = opcode;
+ tpp.len = len;
+ atomic_set(&stop_machine_first, 1);
+ wrote_text = 0;
+ stop_machine(stop_machine_text_poke, (void *)&tpp, NULL);
+ return addr;
+}
+