Merge branch 'audit.b39' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit...

[linux-2.6] / arch / i386 / kernel / alternative.c

diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index d8cda14fff8bc4713f41a15a0193cb935550c602..c3750c2c41137a694be9570443f59b379cc4cc4d 100644 (file)
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -2,12 +2,17 @@
 #include <linux/sched.h>
 #include <linux/spinlock.h>
 #include <linux/list.h>
+#include <linux/kprobes.h>
+#include <linux/mm.h>
+#include <linux/vmalloc.h>
 #include <asm/alternative.h>
 #include <asm/sections.h>
+#include <asm/pgtable.h>
+#include <asm/mce.h>
+#include <asm/nmi.h>
 
-static int noreplace_smp     = 0;
-static int smp_alt_once      = 0;
-static int debug_alternative = 0;
+#ifdef CONFIG_HOTPLUG_CPU
+static int smp_alt_once;
 
 static int __init bootonly(char *str)
 {
@@ -15,6 +20,11 @@ static int __init bootonly(char *str)
        return 1;
 }
 __setup("smp-alt-boot", bootonly);
+#else
+#define smp_alt_once 1
+#endif
+
+static int debug_alternative;
 
 static int __init debug_alt(char *str)
 {
@@ -23,6 +33,8 @@ static int __init debug_alt(char *str)
 }
 __setup("debug-alternative", debug_alt);
 
+static int noreplace_smp;
+
 static int __init setup_noreplace_smp(char *str)
 {
        noreplace_smp = 1;
@@ -144,7 +156,7 @@ static void nop_out(void *insns, unsigned int len)
                unsigned int noplen = len;
                if (noplen > ASM_NOP_MAX)
                        noplen = ASM_NOP_MAX;
-               memcpy(insns, noptable[noplen], noplen);
+               text_poke(insns, noptable[noplen], noplen);
                insns += noplen;
                len -= noplen;
        }
@@ -196,7 +208,7 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end)
                        continue;
                if (*ptr > text_end)
                        continue;
-               **ptr = 0xf0; /* lock prefix */
+               text_poke(*ptr, ((unsigned char []){0xf0}), 1); /* add lock prefix */
        };
 }
 
@@ -354,10 +366,6 @@ void apply_paravirt(struct paravirt_patch_site *start,
                /* Pad the rest with nops */
                nop_out(p->instr + used, p->len - used);
        }
-
-       /* Sync to be conservative, in case we patched following
-        * instructions */
-       sync_core();
 }
 extern struct paravirt_patch_site __start_parainstructions[],
        __stop_parainstructions[];
@@ -367,6 +375,14 @@ 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. */
+       stop_nmi();
+#ifdef CONFIG_MCE
+       stop_mce();
+#endif
+
        local_irq_save(flags);
        apply_alternatives(__alt_instructions, __alt_instructions_end);
 
@@ -376,8 +392,6 @@ void __init alternative_instructions(void)
 #ifdef CONFIG_HOTPLUG_CPU
        if (num_possible_cpus() < 2)
                smp_alt_once = 1;
-#else
-       smp_alt_once = 1;
 #endif
 
 #ifdef CONFIG_SMP
@@ -401,4 +415,37 @@ void __init alternative_instructions(void)
 #endif
        apply_paravirt(__parainstructions, __parainstructions_end);
        local_irq_restore(flags);
+
+       restart_nmi();
+#ifdef CONFIG_MCE
+       restart_mce();
+#endif
+}
+
+/*
+ * Warning:
+ * 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.
+ */
+void __kprobes text_poke(void *oaddr, unsigned char *opcode, int len)
+{
+        u8 *addr = oaddr;
+       if (!pte_write(*lookup_address((unsigned long)addr))) {
+               struct page *p[2] = { virt_to_page(addr), virt_to_page(addr+PAGE_SIZE) };
+               addr = vmap(p, 2, VM_MAP, PAGE_KERNEL);
+               if (!addr)
+                       return;
+               addr += ((unsigned long)oaddr) % PAGE_SIZE;
+       }
+       memcpy(addr, opcode, len);
+       sync_core();
+       /* Not strictly needed, but can speed CPU recovery up. Ignore cross cacheline
+          case. */
+       if (cpu_has_clflush)
+               asm("clflush (%0) " :: "r" (oaddr) : "memory");
+       if (addr != oaddr)
+               vunmap(addr);
 }