x86: move get_segment_eip() to step.c
get_segment_eip has similarities to convert_rip_to_linear(), and is used in a similar context. Move get_segment_eip to step.c to allow easier consolidation. 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>
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4 changed files with 83 additions and 154 deletions
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@ -5,6 +5,87 @@
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#include <linux/mm.h>
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#include <linux/ptrace.h>
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#ifdef CONFIG_X86_32
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#include <linux/uaccess.h>
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#include <asm/desc.h>
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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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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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#ifdef CONFIG_X86_32
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static
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#endif
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@ -61,83 +61,6 @@ 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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* 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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@ -64,83 +64,6 @@ 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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* 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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@ -184,6 +184,8 @@ convert_rip_to_linear(struct task_struct *child, struct pt_regs *regs);
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#ifdef __KERNEL__
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unsigned long get_segment_eip(struct pt_regs *regs, unsigned long *eip_limit);
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/*
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* These are defined as per linux/ptrace.h, which see.
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*/
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