1 files changed, 28 insertions, 12 deletions

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index a84ac7b570e6..2d903b760ddb 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -5,6 +5,7 @@
 #include <linux/kprobes.h>
 #include <linux/mm.h>
 #include <linux/vmalloc.h>
+#include <linux/memory.h>
 #include <asm/alternative.h>
 #include <asm/sections.h>
 #include <asm/pgtable.h>
@@ -12,7 +13,9 @@
 #include <asm/nmi.h>
 #include <asm/vsyscall.h>
 #include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
 #include <asm/io.h>
+#include <asm/fixmap.h>
 
 #define MAX_PATCH_LEN (255-1)
 
@@ -226,6 +229,7 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end)
 {
         u8 **ptr;
 
+        mutex_lock(&text_mutex);
         for (ptr = start; ptr < end; ptr++) {
                 if (*ptr < text)
                         continue;
@@ -234,6 +238,7 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end)
                 /* turn DS segment override prefix into lock prefix */
                 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)
@@ -243,6 +248,7 @@ static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end
         if (noreplace_smp)
                 return;
 
+        mutex_lock(&text_mutex);
         for (ptr = start; ptr < end; ptr++) {
                 if (*ptr < text)
                         continue;
@@ -251,6 +257,7 @@ static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end
                 /* turn lock prefix into DS segment override prefix */
                 text_poke(*ptr, ((unsigned char []){0x3E}), 1);
         };
+        mutex_unlock(&text_mutex);
 }
 
 struct smp_alt_module {
@@ -414,9 +421,17 @@ void __init alternative_instructions(void)
            that might execute the to be patched code.
            Other CPUs are not running. */
         stop_nmi();
-#ifdef CONFIG_X86_MCE
-        stop_mce();
-#endif
+
+        /*
+         * Don't stop machine check exceptions while patching.
+         * MCEs only happen when something got corrupted and in this
+         * case we must do something about the corruption.
+         * Ignoring it is worse than a unlikely patching race.
+         * Also machine checks tend to be broadcast and if one CPU
+         * goes into machine check the others follow quickly, so we don't
+         * expect a machine check to cause undue problems during to code
+         * patching.
+         */
 
         apply_alternatives(__alt_instructions, __alt_instructions_end);
 
@@ -456,9 +471,6 @@ void __init alternative_instructions(void)
                                 (unsigned long)__smp_locks_end);
 
         restart_nmi();
-#ifdef CONFIG_X86_MCE
-        restart_mce();
-#endif
 }
 
 /**
@@ -495,12 +507,13 @@ void *text_poke_early(void *addr, const void *opcode, size_t len)
  * 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.
+ *
+ * Note: Must be called under text_mutex.
  */
 void *__kprobes text_poke(void *addr, const void *opcode, size_t len)
 {
         unsigned long flags;
         char *vaddr;
-        int nr_pages = 2;
         struct page *pages[2];
         int i;
 
@@ -513,14 +526,17 @@ void *__kprobes text_poke(void *addr, const void *opcode, size_t len)
                 pages[1] = virt_to_page(addr + PAGE_SIZE);
         }
         BUG_ON(!pages[0]);
-        if (!pages[1])
-                nr_pages = 1;
-        vaddr = vmap(pages, nr_pages, VM_MAP, PAGE_KERNEL);
-        BUG_ON(!vaddr);
+        set_fixmap(FIX_TEXT_POKE0, page_to_phys(pages[0]));
+        if (pages[1])
+                set_fixmap(FIX_TEXT_POKE1, page_to_phys(pages[1]));
+        vaddr = (char *)fix_to_virt(FIX_TEXT_POKE0);
         local_irq_save(flags);
         memcpy(&vaddr[(unsigned long)addr & ~PAGE_MASK], opcode, len);
         local_irq_restore(flags);
-        vunmap(vaddr);
+        clear_fixmap(FIX_TEXT_POKE0);
+        if (pages[1])
+                clear_fixmap(FIX_TEXT_POKE1);
+        local_flush_tlb();
         sync_core();
         /* Could also do a CLFLUSH here to speed up CPU recovery; but
            that causes hangs on some VIA CPUs. */