[PATCH] i386: Use probe_kernel_address instead of __get_user in fault paths

Makes the intention of the code cleaner to read and avoids
a potential deadlock on mmap_sem. Also change the types of
the arguments to not include __user because they're really
not user addresses.

Signed-off-by: Andi Kleen <ak@suse.de>

2 files changed, 19 insertions, 17 deletions

diff --git a/arch/i386/kernel/traps.c b/arch/i386/kernel/traps.c
index 237f4884a1e1..7b2f9f022089 100644
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -380,7 +380,7 @@ void show_registers(struct pt_regs *regs)
          * time of the fault..
          */
         if (in_kernel) {
-                u8 __user *eip;
+                u8 *eip;
                 int code_bytes = 64;
                 unsigned char c;
 
@@ -389,18 +389,20 @@ void show_registers(struct pt_regs *regs)
 
                 printk(KERN_EMERG "Code: ");
 
-                eip = (u8 __user *)regs->eip - 43;
-                if (eip < (u8 __user *)PAGE_OFFSET || __get_user(c, eip)) {
+                eip = (u8 *)regs->eip - 43;
+                if (eip < (u8 *)PAGE_OFFSET ||
+                        probe_kernel_address(eip, c)) {
                         /* try starting at EIP */
-                        eip = (u8 __user *)regs->eip;
+                        eip = (u8 *)regs->eip;
                         code_bytes = 32;
                 }
                 for (i = 0; i < code_bytes; i++, eip++) {
-                        if (eip < (u8 __user *)PAGE_OFFSET || __get_user(c, eip)) {
+                        if (eip < (u8 *)PAGE_OFFSET ||
+                                probe_kernel_address(eip, c)) {
                                 printk(" Bad EIP value.");
                                 break;
                         }
-                        if (eip == (u8 __user *)regs->eip)
+                        if (eip == (u8 *)regs->eip)
                                 printk("<%02x> ", c);
                         else
                                 printk("%02x ", c);
@@ -416,7 +418,7 @@ static void handle_BUG(struct pt_regs *regs)
 
         if (eip < PAGE_OFFSET)
                 return;
-        if (probe_kernel_address((unsigned short __user *)eip, ud2))
+        if (probe_kernel_address((unsigned short *)eip, ud2))
                 return;
         if (ud2 != 0x0b0f)
                 return;
@@ -429,11 +431,11 @@ static void handle_BUG(struct pt_regs *regs)
                 char *file;
                 char c;
 
-                if (probe_kernel_address((unsigned short __user *)(eip + 2),
-                                        line))
+                if (probe_kernel_address((unsigned short *)(eip + 2), line))
                         break;
-                if (__get_user(file, (char * __user *)(eip + 4)) ||
-                    (unsigned long)file < PAGE_OFFSET || __get_user(c, file))
+                if (probe_kernel_address((char **)(eip + 4), file) ||
+                    (unsigned long)file < PAGE_OFFSET ||
+                        probe_kernel_address(file, c))
                         file = "<bad filename>";
 
                 printk(KERN_EMERG "kernel BUG at %s:%d!\n", file, line);
diff --git a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c
index 2581575786c1..aaaa4d225f7e 100644
--- a/arch/i386/mm/fault.c
+++ b/arch/i386/mm/fault.c
@@ -22,9 +22,9 @@
 #include <linux/highmem.h>
 #include <linux/module.h>
 #include <linux/kprobes.h>
+#include <linux/uaccess.h>
 
 #include <asm/system.h>
-#include <asm/uaccess.h>
 #include <asm/desc.h>
 #include <asm/kdebug.h>
 #include <asm/segment.h>
@@ -167,7 +167,7 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs,
 static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
 { 
         unsigned long limit;
-        unsigned long instr = get_segment_eip (regs, &limit);
+        unsigned char *instr = (unsigned char *)get_segment_eip (regs, &limit);
         int scan_more = 1;
         int prefetch = 0; 
         int i;
@@ -177,9 +177,9 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
                 unsigned char instr_hi;
                 unsigned char instr_lo;
 
-                if (instr > limit)
+                if (instr > (unsigned char *)limit)
                         break;
-                if (__get_user(opcode, (unsigned char __user *) instr))
+                if (probe_kernel_address(instr, opcode))
                         break; 
 
                 instr_hi = opcode & 0xf0; 
@@ -204,9 +204,9 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
                 case 0x00:
                         /* Prefetch instruction is 0x0F0D or 0x0F18 */
                         scan_more = 0;
-                        if (instr > limit)
+                        if (instr > (unsigned char *)limit)
                                 break;
-                        if (__get_user(opcode, (unsigned char __user *) instr))
+                        if (probe_kernel_address(instr, opcode))
                                 break;
                         prefetch = (instr_lo == 0xF) &&
                                 (opcode == 0x0D || opcode == 0x18);