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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>
This commit is contained in:
Harvey Harrison
Ingo Molnar
parent
b6795e65f1
commit
1dc85be087
@ -61,6 +61,7 @@ static inline int notify_page_fault(struct pt_regs *regs)
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#endif
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}
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#ifdef CONFIG_X86_32
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/*
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* Return EIP plus the CS segment base. The segment limit is also
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* adjusted, clamped to the kernel/user address space (whichever is
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@ -135,26 +136,61 @@ static inline unsigned long get_segment_eip(struct pt_regs *regs,
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*eip_limit = seg_limit;
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return ip + base;
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}
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#endif
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/*
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* X86_32
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* Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
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* Check that here and ignore it.
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*
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* X86_64
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* Sometimes the CPU reports invalid exceptions on prefetch.
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* Check that here and ignore it.
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*
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* Opcode checker based on code by Richard Brunner
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*/
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static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
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static int is_prefetch(struct pt_regs *regs, unsigned long addr,
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unsigned long error_code)
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{
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unsigned long limit;
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unsigned char *instr = (unsigned char *)get_segment_eip(regs, &limit);
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unsigned char *instr;
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int scan_more = 1;
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int prefetch = 0;
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int i;
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unsigned char *max_instr;
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for (i = 0; scan_more && i < 15; i++) {
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#ifdef CONFIG_X86_32
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unsigned long limit;
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if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
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boot_cpu_data.x86 >= 6)) {
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/* Catch an obscure case of prefetch inside an NX page. */
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if (nx_enabled && (error_code & PF_INSTR))
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return 0;
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} else {
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return 0;
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}
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instr = (unsigned char *)get_segment_eip(regs, &limit);
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#else
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/* If it was a exec fault ignore */
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if (error_code & PF_INSTR)
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return 0;
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instr = (unsigned char __user *)convert_rip_to_linear(current, regs);
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#endif
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max_instr = instr + 15;
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#ifdef CONFIG_X86_64
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if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE)
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return 0;
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#endif
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while (scan_more && instr < max_instr) {
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unsigned char opcode;
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unsigned char instr_hi;
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unsigned char instr_lo;
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#ifdef CONFIG_X86_32
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if (instr > (unsigned char *)limit)
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break;
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#endif
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if (probe_kernel_address(instr, opcode))
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break;
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@ -196,8 +232,10 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
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case 0x00:
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/* Prefetch instruction is 0x0F0D or 0x0F18 */
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scan_more = 0;
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#ifdef CONFIG_X86_32
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if (instr > (unsigned char *)limit)
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break;
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#endif
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if (probe_kernel_address(instr, opcode))
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break;
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prefetch = (instr_lo == 0xF) &&
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@ -211,19 +249,6 @@ static int __is_prefetch(struct pt_regs *regs, unsigned long addr)
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return prefetch;
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}
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static inline int is_prefetch(struct pt_regs *regs, unsigned long addr,
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unsigned long error_code)
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{
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if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
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boot_cpu_data.x86 >= 6)) {
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/* Catch an obscure case of prefetch inside an NX page. */
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if (nx_enabled && (error_code & 16))
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return 0;
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return __is_prefetch(regs, addr);
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}
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return 0;
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}
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static noinline void force_sig_info_fault(int si_signo, int si_code,
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unsigned long address, struct task_struct *tsk)
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{
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@ -274,6 +299,42 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
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return pmd_k;
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}
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#ifdef CONFIG_X86_64
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static const char errata93_warning[] =
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KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n"
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KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n"
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KERN_ERR "******* Please consider a BIOS update.\n"
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KERN_ERR "******* Disabling USB legacy in the BIOS may also help.\n";
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/* Workaround for K8 erratum #93 & buggy BIOS.
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BIOS SMM functions are required to use a specific workaround
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to avoid corruption of the 64bit RIP register on C stepping K8.
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A lot of BIOS that didn't get tested properly miss this.
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The OS sees this as a page fault with the upper 32bits of RIP cleared.
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Try to work around it here.
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Note we only handle faults in kernel here. */
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static int is_errata93(struct pt_regs *regs, unsigned long address)
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{
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static int warned;
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if (address != regs->ip)
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return 0;
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if ((address >> 32) != 0)
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return 0;
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address |= 0xffffffffUL << 32;
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if ((address >= (u64)_stext && address <= (u64)_etext) ||
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(address >= MODULES_VADDR && address <= MODULES_END)) {
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if (!warned) {
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printk(errata93_warning);
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warned = 1;
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}
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regs->ip = address;
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return 1;
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}
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return 0;
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}
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#endif
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/*
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* Handle a fault on the vmalloc or module mapping area
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*
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@ -64,10 +64,95 @@ static inline int notify_page_fault(struct pt_regs *regs)
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#endif
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}
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/* Sometimes the CPU reports invalid exceptions on prefetch.
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Check that here and ignore.
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Opcode checker based on code by Richard Brunner */
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static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr,
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#ifdef CONFIG_X86_32
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/*
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* Return EIP plus the CS segment base. The segment limit is also
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* adjusted, clamped to the kernel/user address space (whichever is
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* appropriate), and returned in *eip_limit.
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*
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* The segment is checked, because it might have been changed by another
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* task between the original faulting instruction and here.
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*
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* If CS is no longer a valid code segment, or if EIP is beyond the
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* limit, or if it is a kernel address when CS is not a kernel segment,
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* then the returned value will be greater than *eip_limit.
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*
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* This is slow, but is very rarely executed.
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*/
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static inline unsigned long get_segment_eip(struct pt_regs *regs,
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unsigned long *eip_limit)
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{
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unsigned long ip = regs->ip;
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unsigned seg = regs->cs & 0xffff;
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u32 seg_ar, seg_limit, base, *desc;
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/* Unlikely, but must come before segment checks. */
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if (unlikely(regs->flags & VM_MASK)) {
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base = seg << 4;
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*eip_limit = base + 0xffff;
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return base + (ip & 0xffff);
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}
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/* The standard kernel/user address space limit. */
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*eip_limit = user_mode(regs) ? USER_DS.seg : KERNEL_DS.seg;
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/* By far the most common cases. */
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if (likely(SEGMENT_IS_FLAT_CODE(seg)))
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return ip;
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/* Check the segment exists, is within the current LDT/GDT size,
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that kernel/user (ring 0..3) has the appropriate privilege,
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that it's a code segment, and get the limit. */
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__asm__("larl %3,%0; lsll %3,%1"
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: "=&r" (seg_ar), "=r" (seg_limit) : "0" (0), "rm" (seg));
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if ((~seg_ar & 0x9800) || ip > seg_limit) {
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*eip_limit = 0;
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return 1; /* So that returned ip > *eip_limit. */
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}
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/* Get the GDT/LDT descriptor base.
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When you look for races in this code remember that
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LDT and other horrors are only used in user space. */
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if (seg & (1<<2)) {
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/* Must lock the LDT while reading it. */
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mutex_lock(¤t->mm->context.lock);
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desc = current->mm->context.ldt;
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desc = (void *)desc + (seg & ~7);
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} else {
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/* Must disable preemption while reading the GDT. */
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desc = (u32 *)get_cpu_gdt_table(get_cpu());
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desc = (void *)desc + (seg & ~7);
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}
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/* Decode the code segment base from the descriptor */
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base = get_desc_base((struct desc_struct *)desc);
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if (seg & (1<<2))
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mutex_unlock(¤t->mm->context.lock);
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else
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put_cpu();
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/* Adjust EIP and segment limit, and clamp at the kernel limit.
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It's legitimate for segments to wrap at 0xffffffff. */
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seg_limit += base;
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if (seg_limit < *eip_limit && seg_limit >= base)
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*eip_limit = seg_limit;
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return ip + base;
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}
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#endif
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/*
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* X86_32
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* Sometimes AMD Athlon/Opteron CPUs report invalid exceptions on prefetch.
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* Check that here and ignore it.
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*
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* X86_64
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* Sometimes the CPU reports invalid exceptions on prefetch.
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* Check that here and ignore it.
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*
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* Opcode checker based on code by Richard Brunner
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*/
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static int is_prefetch(struct pt_regs *regs, unsigned long addr,
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unsigned long error_code)
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{
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unsigned char *instr;
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@ -75,21 +160,40 @@ static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr,
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int prefetch = 0;
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unsigned char *max_instr;
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#ifdef CONFIG_X86_32
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unsigned long limit;
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if (unlikely(boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
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boot_cpu_data.x86 >= 6)) {
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/* Catch an obscure case of prefetch inside an NX page. */
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if (nx_enabled && (error_code & PF_INSTR))
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return 0;
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} else {
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return 0;
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}
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instr = (unsigned char *)get_segment_eip(regs, &limit);
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#else
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/* If it was a exec fault ignore */
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if (error_code & PF_INSTR)
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return 0;
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instr = (unsigned char __user *)convert_rip_to_linear(current, regs);
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#endif
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max_instr = instr + 15;
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#ifdef CONFIG_X86_64
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if (user_mode(regs) && instr >= (unsigned char *)TASK_SIZE)
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return 0;
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#endif
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while (scan_more && instr < max_instr) {
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unsigned char opcode;
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unsigned char instr_hi;
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unsigned char instr_lo;
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#ifdef CONFIG_X86_32
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if (instr > (unsigned char *)limit)
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break;
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#endif
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if (probe_kernel_address(instr, opcode))
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break;
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@ -125,12 +229,16 @@ static noinline int is_prefetch(struct pt_regs *regs, unsigned long addr,
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scan_more = (instr_lo & 0xC) == 0x4;
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break;
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case 0xF0:
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/* 0xF0, 0xF2, and 0xF3 are valid prefixes in all modes. */
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/* 0xF0, 0xF2, 0xF3 are valid prefixes in all modes. */
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scan_more = !instr_lo || (instr_lo>>1) == 1;
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break;
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case 0x00:
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/* Prefetch instruction is 0x0F0D or 0x0F18 */
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scan_more = 0;
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#ifdef CONFIG_X86_32
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if (instr > (unsigned char *)limit)
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break;
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#endif
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if (probe_kernel_address(instr, opcode))
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break;
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prefetch = (instr_lo == 0xF) &&
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@ -185,6 +293,7 @@ bad:
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printk("BAD\n");
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}
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#ifdef CONFIG_X86_64
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static const char errata93_warning[] =
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KERN_ERR "******* Your BIOS seems to not contain a fix for K8 errata #93\n"
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KERN_ERR "******* Working around it, but it may cause SEGVs or burn power.\n"
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@ -218,6 +327,7 @@ static int is_errata93(struct pt_regs *regs, unsigned long address)
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}
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return 0;
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}
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#endif
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static noinline void pgtable_bad(unsigned long address, struct pt_regs *regs,
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unsigned long error_code)
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