x86: cosmetic fixes fault_{32|64}.c

First step towards unifying these files.
- Checkpatch trailing whitespace fixes
- Checkpatch indentation of switch statement fixes
- Checkpatch single statement ifs need no braces fixes
- Checkpatch consistent spacing after comma fixes
- Introduce defines for pagefault error bits from X86_64 and add useful
  comment from X86_32.  Use these defines in X86_32 where obvious.
- Unify comments between 32|64 bit
- Small ifdef movement for CONFIG_KPROBES in notify_page_fault()
- Introduce X86_64 only case statement

No Functional Changes.

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, 77 insertions, 74 deletions

diff --git a/arch/x86/mm/fault_64.c b/arch/x86/mm/fault_64.c
index 3a94941578fa..7e98a7691283 100644
--- a/arch/x86/mm/fault_64.c
+++ b/arch/x86/mm/fault_64.c
@@ -1,6 +1,4 @@
 /*
- *  linux/arch/x86-64/mm/fault.c
- *
  *  Copyright (C) 1995  Linus Torvalds
  *  Copyright (C) 2001,2002 Andi Kleen, SuSE Labs.
  */
@@ -33,16 +31,23 @@
 #include <asm/proto.h>
 #include <asm-generic/sections.h>
 
-/* Page fault error code bits */
-#define PF_PROT (1<<0)          /* or no page found */
+/*
+ * Page fault error code bits
+ *      bit 0 == 0 means no page found, 1 means protection fault
+ *      bit 1 == 0 means read, 1 means write
+ *      bit 2 == 0 means kernel, 1 means user-mode
+ *      bit 3 == 1 means use of reserved bit detected
+ *      bit 4 == 1 means fault was an instruction fetch
+ */
+#define PF_PROT (1<<0)
 #define PF_WRITE        (1<<1)
 #define PF_USER (1<<2)
 #define PF_RSVD (1<<3)
 #define PF_INSTR        (1<<4)
 
-#ifdef CONFIG_KPROBES
 static inline int notify_page_fault(struct pt_regs *regs)
 {
+#ifdef CONFIG_KPROBES
         int ret = 0;
 
         /* kprobe_running() needs smp_processor_id() */
@@ -54,75 +59,75 @@ static inline int notify_page_fault(struct pt_regs *regs)
         }
 
         return ret;
-}
 #else
-static inline int notify_page_fault(struct pt_regs *regs)
-{
         return 0;
-}
 #endif
+}
 
 /* Sometimes the CPU reports invalid exceptions on prefetch.
    Check that here and ignore.
    Opcode checker based on code by Richard Brunner */
 static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr,
                                 unsigned long error_code)
-{ 
+{
         unsigned char *instr;
         int scan_more = 1;
-        int prefetch = 0; 
+        int prefetch = 0;
         unsigned char *max_instr;
 
         /* If it was a exec fault ignore */
         if (error_code & PF_INSTR)
                 return 0;
-        
+
         instr = (unsigned char __user *)convert_rip_to_linear(current, regs);
         max_instr = instr + 15;
 
         if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE)
                 return 0;
 
-        while (scan_more && instr < max_instr) { 
+        while (scan_more && instr < max_instr) {
                 unsigned char opcode;
                 unsigned char instr_hi;
                 unsigned char instr_lo;
 
                 if (probe_kernel_address(instr, opcode))
-                        break; 
+                        break;
 
-                instr_hi = opcode & 0xf0; 
-                instr_lo = opcode & 0x0f; 
+                instr_hi = opcode & 0xf0;
+                instr_lo = opcode & 0x0f;
                 instr++;
 
-                switch (instr_hi) { 
+                switch (instr_hi) {
                 case 0x20:
                 case 0x30:
-                        /* Values 0x26,0x2E,0x36,0x3E are valid x86
-                           prefixes.  In long mode, the CPU will signal
-                           invalid opcode if some of these prefixes are
-                           present so we will never get here anyway */
+                        /*
+                         * Values 0x26,0x2E,0x36,0x3E are valid x86 prefixes.
+                         * In X86_64 long mode, the CPU will signal invalid
+                         * opcode if some of these prefixes are present so
+                         * X86_64 will never get here anyway
+                         */
                         scan_more = ((instr_lo & 7) == 0x6);
                         break;
-                        
+#ifdef CONFIG_X86_64
                 case 0x40:
-                        /* In AMD64 long mode, 0x40 to 0x4F are valid REX prefixes
-                           Need to figure out under what instruction mode the
-                           instruction was issued ... */
-                        /* Could check the LDT for lm, but for now it's good
-                           enough to assume that long mode only uses well known
-                           segments or kernel. */
+                        /*
+                         * In AMD64 long mode 0x40..0x4F are valid REX prefixes
+                         * Need to figure out under what instruction mode the
+                         * instruction was issued. Could check the LDT for lm,
+                         * but for now it's good enough to assume that long
+                         * mode only uses well known segments or kernel.
+                         */
                         scan_more = (!user_mode(regs)) || (regs->cs == __USER_CS);
                         break;
-                        
+#endif
                 case 0x60:
                         /* 0x64 thru 0x67 are valid prefixes in all modes. */
                         scan_more = (instr_lo & 0xC) == 0x4;
-                        break;          
+                        break;
                 case 0xF0:
                         /* 0xF0, 0xF2, and 0xF3 are valid prefixes in all modes. */
                         scan_more = !instr_lo || (instr_lo>>1) == 1;
-                        break;                  
+                        break;
                 case 0x00:
                         /* Prefetch instruction is 0x0F0D or 0x0F18 */
                         scan_more = 0;
@@ -130,20 +135,20 @@ static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr,
                                 break;
                         prefetch = (instr_lo == 0xF) &&
                                 (opcode == 0x0D || opcode == 0x18);
-                        break;                  
+                        break;
                 default:
                         scan_more = 0;
                         break;
-                } 
+                }
         }
         return prefetch;
 }
 
-static int bad_address(void *p) 
-{ 
+static int bad_address(void *p)
+{
         unsigned long dummy;
         return probe_kernel_address((unsigned long *)p, dummy);
-} 
+}
 
 void dump_pagetable(unsigned long address)
 {
@@ -154,11 +159,11 @@ void dump_pagetable(unsigned long address)
 
         pgd = (pgd_t *)read_cr3();
 
-        pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK); 
+        pgd = __va((unsigned long)pgd & PHYSICAL_PAGE_MASK);
         pgd += pgd_index(address);
         if (bad_address(pgd)) goto bad;
         printk("PGD %lx ", pgd_val(*pgd));
-        if (!pgd_present(*pgd)) goto ret; 
+        if (!pgd_present(*pgd)) goto ret;
 
         pud = pud_offset(pgd, address);
         if (bad_address(pud)) goto bad;
@@ -172,7 +177,7 @@ void dump_pagetable(unsigned long address)
 
         pte = pte_offset_kernel(pmd, address);
         if (bad_address(pte)) goto bad;
-        printk("PTE %lx", pte_val(*pte)); 
+        printk("PTE %lx", pte_val(*pte));
 ret:
         printk("\n");
         return;
@@ -180,7 +185,7 @@ bad:
         printk("BAD\n");
 }
 
-static const char errata93_warning[] = 
+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"
@@ -188,31 +193,31 @@ 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. 
+   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 is_errata93(struct pt_regs *regs, unsigned long address)
 {
         static int warned;
         if (address != regs->ip)
                 return 0;
-        if ((address >> 32) != 0) 
+        if ((address >> 32) != 0)
                 return 0;
         address |= 0xffffffffUL << 32;
-        if ((address >= (u64)_stext && address <= (u64)_etext) || 
-            (address >= MODULES_VADDR && address <= MODULES_END)) { 
+        if ((address >= (u64)_stext && address <= (u64)_etext) ||
+            (address >= MODULES_VADDR && address <= MODULES_END)) {
                 if (!warned) {
-                        printk(errata93_warning);               
+                        printk(errata93_warning);
                         warned = 1;
                 }
                 regs->ip = address;
                 return 1;
         }
         return 0;
-} 
+}
 
 static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
                                  unsigned long error_code)
@@ -296,7 +301,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
 {
         struct task_struct *tsk;
         struct mm_struct *mm;
-        struct vm_area_struct * vma;
+        struct vm_area_struct *vma;
         unsigned long address;
         int write, fault;
         unsigned long flags;
@@ -360,8 +365,8 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
                 pgtable_bad(address, regs, error_code);
 
         /*
-         * If we're in an interrupt or have no user
-         * context, we must not take the fault..
+         * If we're in an interrupt, have no user context or are running in an
+         * atomic region then we must not take the fault.
          */
         if (unlikely(in_atomic() || !mm))
                 goto bad_area_nosemaphore;
@@ -403,7 +408,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
                 goto good_area;
         if (!(vma->vm_flags & VM_GROWSDOWN))
                 goto bad_area;
-        if (error_code & 4) {
+        if (error_code & PF_USER) {
                 /* Allow userspace just enough access below the stack pointer
                  * to let the 'enter' instruction work.
                  */
@@ -420,18 +425,18 @@ good_area:
         info.si_code = SEGV_ACCERR;
         write = 0;
         switch (error_code & (PF_PROT|PF_WRITE)) {
-                default:        /* 3: write, present */
-                        /* fall through */
-                case PF_WRITE:          /* write, not present */
-                        if (!(vma->vm_flags & VM_WRITE))
-                                goto bad_area;
-                        write++;
-                        break;
-                case PF_PROT:           /* read, present */
+        default:        /* 3: write, present */
+                /* fall through */
+        case PF_WRITE:          /* write, not present */
+                if (!(vma->vm_flags & VM_WRITE))
+                        goto bad_area;
+                write++;
+                break;
+        case PF_PROT:           /* read, present */
+                goto bad_area;
+        case 0:                 /* read, not present */
+                if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
                         goto bad_area;
-                case 0:                 /* read, not present */
-                        if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)))
-                                goto bad_area;
         }
 
         /*
@@ -491,7 +496,7 @@ bad_area_nosemaphore:
                                         tsk->comm, tsk->pid, address, regs->ip,
                                         regs->sp, error_code);
                 }
-       
+
                 tsk->thread.cr2 = address;
                 /* Kernel addresses are always protection faults */
                 tsk->thread.error_code = error_code | (address >= TASK_SIZE);
@@ -505,21 +510,19 @@ bad_area_nosemaphore:
         }
 
 no_context:
-        
         /* Are we prepared to handle this kernel fault?  */
-        if (fixup_exception(regs)) {
+        if (fixup_exception(regs))
                 return;
-        }
 
-        /* 
+        /*
          * Hall of shame of CPU/BIOS bugs.
          */
 
-        if (is_prefetch(regs, address, error_code))
-                return;
+        if (is_prefetch(regs, address, error_code))
+                return;
 
         if (is_errata93(regs, address))
-                return; 
+                return;
 
 /*
  * Oops. The kernel tried to access some bad page. We'll have to
@@ -532,7 +535,7 @@ no_context:
                 printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference");
         else
                 printk(KERN_ALERT "Unable to handle kernel paging request");
-        printk(" at %016lx RIP: \n" KERN_ALERT,address);
+        printk(" at %016lx RIP: \n" KERN_ALERT, address);
         printk_address(regs->ip);
         dump_pagetable(address);
         tsk->thread.cr2 = address;
@@ -582,7 +585,7 @@ LIST_HEAD(pgd_list);
 
 void vmalloc_sync_all(void)
 {
-        /* Note that races in the updates of insync and start aren't 
+        /* Note that races in the updates of insync and start aren't
            problematic:
            insync can only get set bits added, and updates to start are only
            improving performance (without affecting correctness if undone). */
@@ -614,6 +617,6 @@ void vmalloc_sync_all(void)
         }
         /* Check that there is no need to do the same for the modules area. */
         BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
-        BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) == 
+        BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
                                 (__START_KERNEL & PGDIR_MASK)));
 }