From: Andi Kleen <ak@suse.de>
Date: Sat, 16 Apr 2005 22:25:00 +0000 (-0700)
Subject: [PATCH] x86_64: Fix interaction of single stepping with debuggers
X-Git-Tag: v2.6.12-rc3~166
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d61915da63e2ef03d9034e3b2ec7d8cca55d7584;p=linux-2.6

[PATCH] x86_64: Fix interaction of single stepping with debuggers

Ported from i386/Linus

Fix another TF corner case.  Need to do the special TF handling for all
signals to make debuggers happy

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/arch/x86_64/kernel/signal.c b/arch/x86_64/kernel/signal.c
index 4ff0f0117a..7760224cdf 100644
--- a/arch/x86_64/kernel/signal.c
+++ b/arch/x86_64/kernel/signal.c
@@ -368,6 +368,18 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 		}
 	}
 
+	/*
+	 * If TF is set due to a debugger (PT_DTRACE), clear the TF
+	 * flag so that register information in the sigcontext is
+	 * correct.
+	 */
+	if (unlikely(regs->eflags & TF_MASK)) {
+		if (likely(current->ptrace & PT_DTRACE)) {
+			current->ptrace &= ~PT_DTRACE;
+			regs->eflags &= ~TF_MASK;
+		}
+	}
+
 #ifdef CONFIG_IA32_EMULATION
 	if (test_thread_flag(TIF_IA32)) {
 		if (ka->sa.sa_flags & SA_SIGINFO)