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, 83 insertions, 65 deletions

diff --git a/arch/x86/mm/fault_32.c b/arch/x86/mm/fault_32.c
index db8d748814e4..bfb0917d699d 100644
--- a/arch/x86/mm/fault_32.c
+++ b/arch/x86/mm/fault_32.c
@@ -1,6 +1,4 @@
 /*
- *  linux/arch/i386/mm/fault.c
- *
  *  Copyright (C) 1995  Linus Torvalds
  */
 
@@ -30,11 +28,25 @@
 #include <asm/desc.h>
 #include <asm/segment.h>
 
-extern void die(const char *,struct pt_regs *,long);
+/*
+ * 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)
+
+extern void die(const char *, struct pt_regs *, long);
 
-#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() */
@@ -46,13 +58,10 @@ 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
+}
 
 /*
  * Return EIP plus the CS segment base.  The segment limit is also
@@ -65,7 +74,7 @@ static inline int notify_page_fault(struct pt_regs *regs)
  * If CS is no longer a valid code segment, or if EIP is beyond the
  * limit, or if it is a kernel address when CS is not a kernel segment,
  * then the returned value will be greater than *eip_limit.
- * 
+ *
  * This is slow, but is very rarely executed.
  */
 static inline unsigned long get_segment_eip(struct pt_regs *regs,
@@ -84,7 +93,7 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs,
 
         /* The standard kernel/user address space limit. */
         *eip_limit = user_mode(regs) ? USER_DS.seg : KERNEL_DS.seg;
-        
+
         /* By far the most common cases. */
         if (likely(SEGMENT_IS_FLAT_CODE(seg)))
                 return ip;
@@ -99,7 +108,7 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs,
                 return 1;        /* So that returned ip > *eip_limit. */
         }
 
-        /* Get the GDT/LDT descriptor base. 
+        /* Get the GDT/LDT descriptor base.
            When you look for races in this code remember that
            LDT and other horrors are only used in user space. */
         if (seg & (1<<2)) {
@@ -109,16 +118,16 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs,
                 desc = (void *)desc + (seg & ~7);
         } else {
                 /* Must disable preemption while reading the GDT. */
-                desc = (u32 *)get_cpu_gdt_table(get_cpu());
+                desc = (u32 *)get_cpu_gdt_table(get_cpu());
                 desc = (void *)desc + (seg & ~7);
         }
 
         /* Decode the code segment base from the descriptor */
         base = get_desc_base((struct desc_struct *)desc);
 
-        if (seg & (1<<2)) { 
+        if (seg & (1<<2))
                 mutex_unlock(&current->mm->context.lock);
-        } else
+        else
                 put_cpu();
 
         /* Adjust EIP and segment limit, and clamp at the kernel limit.
@@ -129,19 +138,19 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs,
         return ip + base;
 }
 
-/* 
+/*
  * Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
  * Check that here and ignore it.
  */
 static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
-{ 
+{
         unsigned long limit;
-        unsigned char *instr = (unsigned char *)get_segment_eip (regs, &limit);
+        unsigned char *instr = (unsigned char *)get_segment_eip(regs, &limit);
         int scan_more = 1;
-        int prefetch = 0; 
+        int prefetch = 0;
         int i;
 
-        for (i = 0; scan_more && i < 15; i++) { 
+        for (i = 0; scan_more && i < 15; i++) {
                 unsigned char opcode;
                 unsigned char instr_hi;
                 unsigned char instr_lo;
@@ -149,27 +158,43 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
                 if (instr > (unsigned char *)limit)
                         break;
                 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. */
+                        /*
+                         * 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..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 */
+                        /* 0xF0, 0xF2, 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;
@@ -179,11 +204,11 @@ static 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;
 }
@@ -199,7 +224,7 @@ static inline int is_prefetch(struct pt_regs *regs, unsigned long addr,
                 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)
@@ -284,19 +309,12 @@ int show_unhandled_signals = 1;
  * This routine handles page faults.  It determines the address,
  * and the problem, and then passes it off to one of the appropriate
  * routines.
- *
- * error_code:
- *      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
  */
 void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
 {
         struct task_struct *tsk;
         struct mm_struct *mm;
-        struct vm_area_struct * vma;
+        struct vm_area_struct *vma;
         unsigned long address;
         int write, si_code;
         int fault;
@@ -307,7 +325,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
         trace_hardirqs_fixup();
 
         /* get the address */
-        address = read_cr2();
+        address = read_cr2();
 
         tsk = current;
 
@@ -350,7 +368,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
 
         /*
          * If we're in an interrupt, have no user context or are running in an
-         * atomic region then we must not take the fault..
+         * atomic region then we must not take the fault.
          */
         if (in_atomic() || !mm)
                 goto bad_area_nosemaphore;
@@ -371,7 +389,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
          * thus avoiding the deadlock.
          */
         if (!down_read_trylock(&mm->mmap_sem)) {
-                if ((error_code & 4) == 0 &&
+                if ((error_code & PF_USER) == 0 &&
                     !search_exception_tables(regs->ip))
                         goto bad_area_nosemaphore;
                 down_read(&mm->mmap_sem);
@@ -384,7 +402,7 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
                 goto good_area;
         if (!(vma->vm_flags & VM_GROWSDOWN))
                 goto bad_area;
-        if (error_code & 4) {
+        if (error_code & PF_USER) {
                 /*
                  * Accessing the stack below %sp is always a bug.
                  * The large cushion allows instructions like enter
@@ -403,19 +421,19 @@ void __kprobes do_page_fault(struct pt_regs *regs, unsigned long error_code)
 good_area:
         si_code = SEGV_ACCERR;
         write = 0;
-        switch (error_code & 3) {
-                default:        /* 3: write, present */
-                                /* fall through */
-                case 2:         /* write, not present */
-                        if (!(vma->vm_flags & VM_WRITE))
-                                goto bad_area;
-                        write++;
-                        break;
-                case 1:         /* read, present */
+        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 */
+                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;
         }
 
  survive:
@@ -457,14 +475,14 @@ bad_area:
 
 bad_area_nosemaphore:
         /* User mode accesses just cause a SIGSEGV */
-        if (error_code & 4) {
+        if (error_code & PF_USER) {
                 /*
                  * It's possible to have interrupts off here.
                  */
                 local_irq_enable();
 
-                /* 
-                 * Valid to do another page fault here because this one came 
+                /*
+                 * Valid to do another page fault here because this one came
                  * from user space.
                  */
                 if (is_prefetch(regs, address, error_code))
@@ -492,7 +510,7 @@ bad_area_nosemaphore:
          */
         if (boot_cpu_data.f00f_bug) {
                 unsigned long nr;
-                
+
                 nr = (address - idt_descr.address) >> 3;
 
                 if (nr == 6) {
@@ -507,13 +525,13 @@ no_context:
         if (fixup_exception(regs))
                 return;
 
-        /* 
+        /*
          * Valid to do another page fault here, because if this fault
-         * had been triggered by is_prefetch fixup_exception would have 
+         * had been triggered by is_prefetch fixup_exception would have
          * handled it.
          */
-        if (is_prefetch(regs, address, error_code))
-                return;
+        if (is_prefetch(regs, address, error_code))
+                return;
 
 /*
  * Oops. The kernel tried to access some bad page. We'll have to
@@ -541,7 +559,7 @@ no_context:
                 else
                         printk(KERN_ALERT "BUG: unable to handle kernel paging"
                                         " request");
-                printk(" at virtual address %08lx\n",address);
+                printk(" at virtual address %08lx\n", address);
                 printk(KERN_ALERT "printing ip: %08lx ", regs->ip);
 
                 page = read_cr3();
@@ -605,7 +623,7 @@ do_sigbus:
         up_read(&mm->mmap_sem);
 
         /* Kernel mode? Handle exceptions or die */
-        if (!(error_code & 4))
+        if (!(error_code & PF_USER))
                 goto no_context;
 
         /* User space => ok to do another page fault */