Let GDB monitor use HLT for breakpoints, fix #83

The patch fixes a corner-case problem with using the two-byte 'INT 0'
instruction for breakpoints. The fix changes the breakpoint instruction
to the single-byte 'HLT'. 'HLT' is a privileged instruction and triggers
an exception when executed in user mode. Patch by Christian Prochaska.
This commit is contained in:
Norman Feske 2012-01-13 20:07:15 +01:00
parent 441d672440
commit cc85dc8afb

View File

@ -584,18 +584,23 @@ diff --git a/gdb/gdbserver/linux-x86-low.c b/gdb/gdbserver/linux-x86-low.c
}
static void
@@ -414,8 +443,8 @@
@@ -414,7 +443,15 @@
}
}
-static const unsigned char x86_breakpoint[] = { 0xCC };
-#define x86_breakpoint_len 1
+static const unsigned char x86_breakpoint[] = { /*0xCC*/0xCD, 0x00 };
+#define x86_breakpoint_len 2
+#ifdef __GENODE__
+/* The 'INT3' instruction is used by some kernel debuggers and thus cannot
+ * serve as breakpoint instruction for the GDB monitor. Instead, the 'HLT'
+ * instruction gets used. It's a privileged instruction which triggers an
+ * exception when executed in user mode */
+static const unsigned char x86_breakpoint[] = { 0xF4 };
+#else
static const unsigned char x86_breakpoint[] = { 0xCC };
+#endif
#define x86_breakpoint_len 1
static int
x86_breakpoint_at (CORE_ADDR pc)
@@ -2576,7 +2605,7 @@
@@ -2576,7 +2613,7 @@
x86_siginfo_fixup,
x86_linux_new_process,
x86_linux_new_thread,