hw-breakpoints: Fix broken a.out format dump

Fix the broken a.out format dump. For now we only dump the ptrace breakpoints. TODO: Dump every perf breakpoints for the current thread, not only ptrace based ones. Reported-by: Ingo Molnar <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> Cc: "K. Prasad" <[email protected]>
mrwenhui · Nov 10, 2009 · 9f6b3c2 · 9f6b3c2
1 parent 676c0db
commit 9f6b3c2
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Showing 3 changed files with 39 additions and 8 deletions.
diff --git a/arch/x86/include/asm/a.out-core.h b/arch/x86/include/asm/a.out-core.h
@@ -17,6 +17,7 @@
 
 #include <linux/user.h>
 #include <linux/elfcore.h>
+#include <asm/debugreg.h>
 
 /*
  * fill in the user structure for an a.out core dump
@@ -32,14 +33,7 @@ static inline void aout_dump_thread(struct pt_regs *regs, struct user *dump)
 			>> PAGE_SHIFT;
 	dump->u_dsize -= dump->u_tsize;
 	dump->u_ssize = 0;
-	dump->u_debugreg[0] = current->thread.debugreg[0];
-	dump->u_debugreg[1] = current->thread.debugreg[1];
-	dump->u_debugreg[2] = current->thread.debugreg[2];
-	dump->u_debugreg[3] = current->thread.debugreg[3];
-	dump->u_debugreg[4] = 0;
-	dump->u_debugreg[5] = 0;
-	dump->u_debugreg[6] = current->thread.debugreg6;
-	dump->u_debugreg[7] = current->thread.debugreg7;
+	aout_dump_debugregs(dump);
 
 	if (dump->start_stack < TASK_SIZE)
 		dump->u_ssize = ((unsigned long)(TASK_SIZE - dump->start_stack))

diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
@@ -89,6 +89,8 @@ static inline void hw_breakpoint_disable(void)
 	set_debugreg(0UL, 3);
 }
 
+extern void aout_dump_debugregs(struct user *dump);
+
 #ifdef CONFIG_KVM
 extern void hw_breakpoint_restore(void);
 #endif

diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
@@ -375,6 +375,41 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp,
 	return 0;
 }
 
+/*
+ * Dump the debug register contents to the user.
+ * We can't dump our per cpu values because it
+ * may contain cpu wide breakpoint, something that
+ * doesn't belong to the current task.
+ *
+ * TODO: include non-ptrace user breakpoints (perf)
+ */
+void aout_dump_debugregs(struct user *dump)
+{
+	int i;
+	int dr7 = 0;
+	struct perf_event *bp;
+	struct arch_hw_breakpoint *info;
+	struct thread_struct *thread = &current->thread;
+
+	for (i = 0; i < HBP_NUM; i++) {
+		bp = thread->ptrace_bps[i];
+
+		if (bp && !bp->attr.disabled) {
+			dump->u_debugreg[i] = bp->attr.bp_addr;
+			info = counter_arch_bp(bp);
+			dr7 |= encode_dr7(i, info->len, info->type);
+		} else {
+			dump->u_debugreg[i] = 0;
+		}
+	}
+
+	dump->u_debugreg[4] = 0;
+	dump->u_debugreg[5] = 0;
+	dump->u_debugreg[6] = current->thread.debugreg6;
+
+	dump->u_debugreg[7] = dr7;
+}
+
 /*
  * Release the user breakpoints used by ptrace
  */