x86: begin fault_{32|64}.c unification

Move X86_32 only get_segment_eip to X86_64
Move X86_64 only is_errata93 to X86_32

Change X86_32 loop in is_prefetch to highlight the differences
between them.  Fold the logic from __is_prefetch in as well on
X86_32.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 79 insertions, 18 deletions

diff --git a/arch/x86/mm/fault_32.c b/arch/x86/mm/fault_32.c
index 870b5610555c..300c9d8b684a 100644
--- a/arch/x86/mm/fault_32.c
+++ b/arch/x86/mm/fault_32.c
@@ -61,6 +61,7 @@ static inline int notify_page_fault(struct pt_regs *regs)
 #endif
 }
 
+#ifdef CONFIG_X86_32
 /*
  * Return EIP plus the CS segment base.  The segment limit is also
  * adjusted, clamped to the kernel/user address space (whichever is
@@ -135,26 +136,61 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs,
                 *eip_limit = seg_limit;
         return ip + base;
 }
+#endif
 
 /*
+ * X86_32
  * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
  * Check that here and ignore it.
+ *
+ * X86_64
+ * Sometimes the CPU reports invalid exceptions on prefetch.
+ * Check that here and ignore it.
+ *
+ * Opcode checker based on code by Richard Brunner
  */
-static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
+static int is_prefetch(struct pt_regs *regs, unsigned long addr,
+                       unsigned long error_code)
 {
-        unsigned long limit;
-        unsigned char *instr = (unsigned char *)get_segment_eip(regs, &limit);
+        unsigned char *instr;
         int scan_more = 1;
         int prefetch = 0;
-        int i;
+        unsigned char *max_instr;
+
+#ifdef CONFIG_X86_32
+        unsigned long limit;
+        if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
+                     boot_cpu_data.x86 >= 6)) {
+                /* Catch an obscure case of prefetch inside an NX page. */
+                if (nx_enabled && (error_code & PF_INSTR))
+                        return 0;
+        } else {
+                return 0;
+        }
+        instr = (unsigned char *)get_segment_eip(regs, &limit);
+#else
+        /* If it was a exec fault ignore */
+        if (error_code & PF_INSTR)
+                return 0;
+        instr = (unsigned char __user *)convert_rip_to_linear(current, regs);
+#endif
+
+        max_instr = instr + 15;
+
+#ifdef CONFIG_X86_64
+        if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE)
+                return 0;
+#endif
 
-        for (i = 0; scan_more && i < 15; i++) {
+        while (scan_more && instr < max_instr) {
                 unsigned char opcode;
                 unsigned char instr_hi;
                 unsigned char instr_lo;
 
+#ifdef CONFIG_X86_32
                 if (instr > (unsigned char *)limit)
                         break;
+#endif
                 if (probe_kernel_address(instr, opcode))
                         break;
 
@@ -196,8 +232,10 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
                 case 0x00:
                         /* Prefetch instruction is 0x0F0D or 0x0F18 */
                         scan_more = 0;
+#ifdef CONFIG_X86_32
                         if (instr > (unsigned char *)limit)
                                 break;
+#endif
                         if (probe_kernel_address(instr, opcode))
                                 break;
                         prefetch = (instr_lo == 0xF) &&
@@ -211,19 +249,6 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
         return prefetch;
 }
 
-static inline int is_prefetch(struct pt_regs *regs, unsigned long addr,
-                              unsigned long error_code)
-{
-        if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
-                     boot_cpu_data.x86 >= 6)) {
-                /* Catch an obscure case of prefetch inside an NX page. */
-                if (nx_enabled && (error_code & 16))
-                        return 0;
-                return __is_prefetch(regs, addr);
-        }
-        return 0;
-}
-
 static noinline void force_sig_info_fault(int si_signo, int si_code,
         unsigned long address, struct task_struct *tsk)
 {
@@ -274,6 +299,42 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
         return pmd_k;
 }
 
+#ifdef CONFIG_X86_64
+static const char errata93_warning[] =
+KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n"
+KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n"
+KERN_ERR "******* Please consider a BIOS update.\n"
+KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
+
+/* Workaround for K8 erratum #93 & buggy BIOS.
+   BIOS SMM functions are required to use a specific workaround
+   to avoid corruption of the 64bit RIP register on C stepping K8.
+   A lot of BIOS that didn't get tested properly miss this.
+   The OS sees this as a page fault with the upper 32bits of RIP cleared.
+   Try to work around it here.
+   Note we only handle faults in kernel here. */
+
+static int is_errata93(struct pt_regs *regs, unsigned long address)
+{
+        static int warned;
+        if (address != regs->ip)
+                return 0;
+        if ((address >> 32) != 0)
+                return 0;
+        address |= 0xffffffffUL << 32;
+        if ((address >= (u64)_stext && address <= (u64)_etext) ||
+            (address >= MODULES_VADDR && address <= MODULES_END)) {
+                if (!warned) {
+                        printk(errata93_warning);
+                        warned = 1;
+                }
+                regs->ip = address;
+                return 1;
+        }
+        return 0;
+}
+#endif
+
 /*
  * Handle a fault on the vmalloc or module mapping area
  *