[PATCH v2 1/2] Add i386 support for endbr skipping

Victor Collod
2020-06-11T22:56:38Z

2020-06-11 Victor Collod <vcollod@nvidia.com>

* i386-tdep.c (i386_skip_endbr): Add a helper function to skip endbr.
(i386_analyze_prologue): Call i386_skip_endbr.
---
gdb/i386-tdep.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c
index 9b905c1996a..263a3fd452e 100644
--- a/gdb/i386-tdep.c
+++ b/gdb/i386-tdep.c
@@ -1537,6 +1537,24 @@ struct i386_insn i386_frame_setup_skip_insns[] =
{ 0 }
};

+/* Check whether PC points to an endbr32 instruction. */
+static CORE_ADDR
+i386_skip_endbr (CORE_ADDR pc)
+{
+ static const gdb_byte endbr32[] = { 0xf3, 0x0f, 0x1e, 0xfb };
+
+ gdb_byte buf[sizeof (endbr32)];
+
+ /* Stop there if we can't read the code */
+ if (target_read_code (pc, buf, sizeof (endbr32)))
+ return pc;
+
+ /* If the instruction isn't an endbr32, stop */
+ if (memcmp (buf, endbr32, sizeof (endbr32)) != 0)
+ return pc;
+
+ return pc + sizeof (endbr32);
+}

/* Check whether PC points to a no-op instruction. */
static CORE_ADDR
@@ -1814,6 +1832,7 @@ i386_analyze_prologue (struct gdbarch *gdbarch,
CORE_ADDR pc, CORE_ADDR current_pc,
struct i386_frame_cache *cache)
{
+ pc = i386_skip_endbr (pc);
pc = i386_skip_noop (pc);
pc = i386_follow_jump (gdbarch, pc);
pc = i386_analyze_struct_return (pc, current_pc, cache);
--
2.20.1