x86: remove last user of get_segment_eip

is_prefetch was the last user of get_segment_eip and only on
X86_32.  This function returned the faulting instruction's
address and set the upper segment limit.

Instead, use the convert_ip_to_linear helper and rely on
probe_kernel_address to do the segment checks which was
already done everywhere the segment limit was being checked
on X86_32.

Remove get_segment_eip as well.

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, 0 insertions, 84 deletions

diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index 80b37181a42b..2ef1a5f8d675 100644
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -5,90 +5,6 @@
 #include <linux/mm.h>
 #include <linux/ptrace.h>
 
-#ifdef CONFIG_X86_32
-#include <linux/uaccess.h>
-
-#include <asm/desc.h>
-
-/*
- * Return EIP plus the CS segment base.  The segment limit is also
- * adjusted, clamped to the kernel/user address space (whichever is
- * appropriate), and returned in *eip_limit.
- *
- * The segment is checked, because it might have been changed by another
- * task between the original faulting instruction and here.
- *
- * 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.
- */
-unsigned long get_segment_eip(struct pt_regs *regs,
-                                            unsigned long *eip_limit)
-{
-        unsigned long ip = regs->ip;
-        unsigned seg = regs->cs & 0xffff;
-        u32 seg_ar, seg_limit, base, *desc;
-
-        /* Unlikely, but must come before segment checks. */
-        if (unlikely(regs->flags & VM_MASK)) {
-                base = seg << 4;
-                *eip_limit = base + 0xffff;
-                return base + (ip & 0xffff);
-        }
-
-        /* 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;
-
-        /* Check the segment exists, is within the current LDT/GDT size,
-           that kernel/user (ring 0..3) has the appropriate privilege,
-           that it's a code segment, and get the limit. */
-        __asm__("larl %3,%0; lsll %3,%1"
-                 : "=&r" (seg_ar), "=r" (seg_limit) : "0" (0), "rm" (seg));
-        if ((~seg_ar & 0x9800) || ip > seg_limit) {
-                *eip_limit = 0;
-                return 1;        /* So that returned ip > *eip_limit. */
-        }
-
-        /* 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)) {
-                /* Must lock the LDT while reading it. */
-                mutex_lock(&current->mm->context.lock);
-                desc = current->mm->context.ldt;
-                desc = (void *)desc + (seg & ~7);
-        } else {
-                /* Must disable preemption while reading the GDT. */
-                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))
-                mutex_unlock(&current->mm->context.lock);
-        else
-                put_cpu();
-
-        /* Adjust EIP and segment limit, and clamp at the kernel limit.
-           It's legitimate for segments to wrap at 0xffffffff. */
-        seg_limit += base;
-        if (seg_limit < *eip_limit && seg_limit >= base)
-                *eip_limit = seg_limit;
-        return ip + base;
-}
-#endif
-
-#ifdef CONFIG_X86_32
-static
-#endif
 unsigned long convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs)
 {
         unsigned long addr, seg;