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Diffstat (limited to 'arch/x86/kernel/process_32.c')
-rw-r--r--arch/x86/kernel/process_32.c26
1 files changed, 2 insertions, 24 deletions
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index 209e74801763..d5bd3132ee70 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -59,7 +59,6 @@
#include <asm/syscalls.h>
#include <asm/ds.h>
#include <asm/debugreg.h>
-#include <asm/hw_breakpoint.h>
asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
@@ -264,9 +263,8 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
p->thread.io_bitmap_ptr = NULL;
tsk = current;
err = -ENOMEM;
- if (unlikely(test_tsk_thread_flag(tsk, TIF_DEBUG)))
- if (copy_thread_hw_breakpoint(tsk, p, clone_flags))
- goto out;
+
+ memset(p->thread.ptrace_bps, 0, sizeof(p->thread.ptrace_bps));
if (unlikely(test_tsk_thread_flag(tsk, TIF_IO_BITMAP))) {
p->thread.io_bitmap_ptr = kmemdup(tsk->thread.io_bitmap_ptr,
@@ -287,13 +285,10 @@ int copy_thread(unsigned long clone_flags, unsigned long sp,
err = do_set_thread_area(p, -1,
(struct user_desc __user *)childregs->si, 0);
-out:
if (err && p->thread.io_bitmap_ptr) {
kfree(p->thread.io_bitmap_ptr);
p->thread.io_bitmap_max = 0;
}
- if (err)
- flush_thread_hw_breakpoint(p);
clear_tsk_thread_flag(p, TIF_DS_AREA_MSR);
p->thread.ds_ctx = NULL;
@@ -437,23 +432,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
lazy_load_gs(next->gs);
percpu_write(current_task, next_p);
- /*
- * There's a problem with moving the arch_install_thread_hw_breakpoint()
- * call before current is updated. Suppose a kernel breakpoint is
- * triggered in between the two, the hw-breakpoint handler will see that
- * the 'current' task does not have TIF_DEBUG flag set and will think it
- * is leftover from an old task (lazy switching) and will erase it. Then
- * until the next context switch, no user-breakpoints will be installed.
- *
- * The real problem is that it's impossible to update both current and
- * physical debug registers at the same instant, so there will always be
- * a window in which they disagree and a breakpoint might get triggered.
- * Since we use lazy switching, we are forced to assume that a
- * disagreement means that current is correct and the exception is due
- * to lazy debug register switching.
- */
- if (unlikely(test_tsk_thread_flag(next_p, TIF_DEBUG)))
- arch_install_thread_hw_breakpoint(next_p);
return prev_p;
}