[PATCH v3 1/7] Add i386 support for endbr skipping

[Victor Collod <vcollod@nvidia.com>]

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

gdb/ChangeLog:

	* i386-tdep.c (i386_skip_endbr): Add a helper function to skip endbr.
	(i386_analyze_prologue): Call i386_skip_endbr.

gdb/testsuite/ChangeLog:

	* gdb.arch/amd64-prologue-skip-cf-protection.exp: Make the test
	compatible with i386, and move it to...
	* gdb.arch/i386-prologue-skip-cf-protection.exp: ... here.
	* gdb.arch/amd64-prologue-skip-cf-protection.c: Move to...
	* gdb.arch/i386-prologue-skip-cf-protection.c: ... here.
---
 gdb/i386-tdep.c                               | 19 +++++++++++++++++++
 ...n.c => i386-prologue-skip-cf-protection.c} |  0
 ...p => i386-prologue-skip-cf-protection.exp} |  2 +-
 3 files changed, 20 insertions(+), 1 deletion(-)
 rename gdb/testsuite/gdb.arch/{amd64-prologue-skip-cf-protection.c => i386-prologue-skip-cf-protection.c} (100%)
 rename gdb/testsuite/gdb.arch/{amd64-prologue-skip-cf-protection.exp => i386-prologue-skip-cf-protection.exp} (97%)

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);
diff --git a/gdb/testsuite/gdb.arch/amd64-prologue-skip-cf-protection.c b/gdb/testsuite/gdb.arch/i386-prologue-skip-cf-protection.c
similarity index 100%
rename from gdb/testsuite/gdb.arch/amd64-prologue-skip-cf-protection.c
rename to gdb/testsuite/gdb.arch/i386-prologue-skip-cf-protection.c
diff --git a/gdb/testsuite/gdb.arch/amd64-prologue-skip-cf-protection.exp b/gdb/testsuite/gdb.arch/i386-prologue-skip-cf-protection.exp
similarity index 97%
rename from gdb/testsuite/gdb.arch/amd64-prologue-skip-cf-protection.exp
rename to gdb/testsuite/gdb.arch/i386-prologue-skip-cf-protection.exp
index 3c51fd30352..612c6edf9f1 100644
--- a/gdb/testsuite/gdb.arch/amd64-prologue-skip-cf-protection.exp
+++ b/gdb/testsuite/gdb.arch/i386-prologue-skip-cf-protection.exp
@@ -22,7 +22,7 @@
 standard_testfile .c
 set binfile ${binfile}
 
-if { ![istarget x86_64-*-* ] || ![is_lp64_target] } {
+if { ![istarget x86_64-*-*] && ![istarget i?86-*-*] } {
     verbose "Skipping ${testfile}."
     return
 }
-- 
2.20.1