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authorRoland McGrath <roland@redhat.com>2008-01-30 13:30:50 +0100
committerIngo Molnar <mingo@elte.hu>2008-01-30 13:30:50 +0100
commite1f287735c1e58c653b516931b5d3dd899edcb77 (patch)
tree1a2948cfe8ff679135971e2c573d11b847fee93d /arch/x86/ia32
parent7122ec8158b0f88befd94f4da8feae2c8d08d1b4 (diff)
downloadlinux-e1f287735c1e58c653b516931b5d3dd899edcb77.tar.bz2
x86 single_step: TIF_FORCED_TF
This changes the single-step support to use a new thread_info flag TIF_FORCED_TF instead of the PT_DTRACE flag in task_struct.ptrace. This keeps arch implementation uses out of this non-arch field. This changes the ptrace access to eflags to mask TF and maintain the TIF_FORCED_TF flag directly if userland sets TF, instead of relying on ptrace_signal_deliver. The 64-bit and 32-bit kernels are harmonized on this same behavior. The ptrace_signal_deliver approach works now, but this change makes the low-level register access code reliable when called from different contexts than a ptrace stop, which will be possible in the future. The 64-bit do_debug exception handler is also changed not to clear TF from user-mode registers. This matches the 32-bit kernel's behavior. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/ia32')
-rw-r--r--arch/x86/ia32/ptrace32.c20
1 files changed, 18 insertions, 2 deletions
diff --git a/arch/x86/ia32/ptrace32.c b/arch/x86/ia32/ptrace32.c
index 9d754b640205..5dee33417313 100644
--- a/arch/x86/ia32/ptrace32.c
+++ b/arch/x86/ia32/ptrace32.c
@@ -89,6 +89,15 @@ static int putreg32(struct task_struct *child, unsigned regno, u32 val)
__u64 *flags = &stack[offsetof(struct pt_regs, eflags)/8];
val &= FLAG_MASK;
+ /*
+ * If the user value contains TF, mark that
+ * it was not "us" (the debugger) that set it.
+ * If not, make sure it stays set if we had.
+ */
+ if (val & X86_EFLAGS_TF)
+ clear_tsk_thread_flag(child, TIF_FORCED_TF);
+ else if (test_tsk_thread_flag(child, TIF_FORCED_TF))
+ val |= X86_EFLAGS_TF;
*flags = val | (*flags & ~FLAG_MASK);
break;
}
@@ -179,9 +188,17 @@ static int getreg32(struct task_struct *child, unsigned regno, u32 *val)
R32(eax, rax);
R32(orig_eax, orig_rax);
R32(eip, rip);
- R32(eflags, eflags);
R32(esp, rsp);
+ case offsetof(struct user32, regs.eflags):
+ /*
+ * If the debugger set TF, hide it from the readout.
+ */
+ *val = stack[offsetof(struct pt_regs, eflags)/8];
+ if (test_tsk_thread_flag(child, TIF_FORCED_TF))
+ *val &= ~X86_EFLAGS_TF;
+ break;
+
case offsetof(struct user32, u_debugreg[0]):
*val = child->thread.debugreg0;
break;
@@ -425,4 +442,3 @@ asmlinkage long sys32_ptrace(long request, u32 pid, u32 addr, u32 data)
put_task_struct(child);
return ret;
}
-