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author | Victor Collod <vcollod@nvidia.com> | 2020-09-18 17:53:02 -0700 |
---|---|---|
committer | H.J. Lu <hjl.tools@gmail.com> | 2020-09-18 17:53:34 -0700 |
commit | 14f9473ca225290680c8b21240cdca49f8d3b332 (patch) | |
tree | b3dbcee34e32092afbe435d4d47f83fbb9619651 | |
parent | febd44f94d944c9058b387a784124dc8e0de58ee (diff) | |
download | gdb-14f9473ca225290680c8b21240cdca49f8d3b332.zip gdb-14f9473ca225290680c8b21240cdca49f8d3b332.tar.gz gdb-14f9473ca225290680c8b21240cdca49f8d3b332.tar.bz2 |
gdb: Update i386_analyze_prologue to skip endbr32
With -m32 -fcf-protection, GCC generates an `endbr32` instruction at the
function entry:
[hjl@gnu-cfl-2 gdb]$ cat /tmp/x.c
int
main(void)
{
return 0;
}
[hjl@gnu-cfl-2 gdb]$ gcc -g -fcf-protection /tmp/x.c -m32
(gdb) b main
Breakpoint 1 at 0x8049176: file /tmp/x.c, line 3.
(gdb) r
Breakpoint 1, main () at /tmp/x.c:3
3 {
(gdb) disass
Dump of assembler code for function main:
=> 0x08049176 <+0>: endbr32
0x0804917a <+4>: push %ebp
0x0804917b <+5>: mov %esp,%ebp
0x0804917d <+7>: mov $0x0,%eax
0x08049182 <+12>: pop %ebp
0x08049183 <+13>: ret
End of assembler dump.
(gdb)
Update i386_analyze_prologue to skip `endbr32`:
(gdb) b main
Breakpoint 1 at 0x804917d: file /tmp/x.c, line 4.
(gdb) r
Breakpoint 1, main () at /tmp/x.c:4
4 return 0;
(gdb) disass
Dump of assembler code for function main:
0x08049176 <+0>: endbr32
0x0804917a <+4>: push %ebp
0x0804917b <+5>: mov %esp,%ebp
=> 0x0804917d <+7>: mov $0x0,%eax
0x08049182 <+12>: pop %ebp
0x08049183 <+13>: ret
End of assembler dump.
(gdb)
Tested with
$ make check RUNTESTFLAGS="--target_board='unix{-m32,}' i386-prologue-skip-cf-protection.exp"
on Fedora 32/x86-64.
2020-0X-YY Victor Collod <vcollod@nvidia.com>
gdb/ChangeLog:
PR gdb/26635
* i386-tdep.c (i386_skip_endbr): Add a helper function to skip endbr.
(i386_analyze_prologue): Call i386_skip_endbr.
gdb/testsuite/ChangeLog:
PR gdb/26635
* 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.
-rw-r--r-- | gdb/ChangeLog | 6 | ||||
-rw-r--r-- | gdb/i386-tdep.c | 19 | ||||
-rw-r--r-- | gdb/testsuite/ChangeLog | 9 | ||||
-rw-r--r-- | gdb/testsuite/gdb.arch/i386-prologue-skip-cf-protection.c (renamed from gdb/testsuite/gdb.arch/amd64-prologue-skip-cf-protection.c) | 0 | ||||
-rw-r--r-- | gdb/testsuite/gdb.arch/i386-prologue-skip-cf-protection.exp (renamed from gdb/testsuite/gdb.arch/amd64-prologue-skip-cf-protection.exp) | 6 |
5 files changed, 37 insertions, 3 deletions
diff --git a/gdb/ChangeLog b/gdb/ChangeLog index a052d4f..8b010e5 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2020-09-18 Victor Collod <vcollod@nvidia.com> + + PR gdb/26635 + * i386-tdep.c (i386_skip_endbr): Add a helper function to skip endbr. + (i386_analyze_prologue): Call i386_skip_endbr. + 2020-09-18 Tom Tromey <tromey@adacore.com> * windows-nat.c (struct windows_nat_target) <wait>: Update. diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c index 95cfe5b..b485f0b 100644 --- a/gdb/i386-tdep.c +++ b/gdb/i386-tdep.c @@ -1538,6 +1538,24 @@ 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 @@ -1815,6 +1833,7 @@ 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/ChangeLog b/gdb/testsuite/ChangeLog index ef4006b..b7c1ce8 100644 --- a/gdb/testsuite/ChangeLog +++ b/gdb/testsuite/ChangeLog @@ -1,3 +1,12 @@ +2020-09-18 Victor Collod <vcollod@nvidia.com> + + PR gdb/26635 + * 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. + 2020-09-18 Pedro Alves <pedro@palves.net> PR gdb/26631 diff --git a/gdb/testsuite/gdb.arch/amd64-prologue-skip-cf-protection.c b/gdb/testsuite/gdb.arch/i386-prologue-skip-cf-protection.c index a650585..a650585 100644 --- a/gdb/testsuite/gdb.arch/amd64-prologue-skip-cf-protection.c +++ b/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 index 3c51fd3..9ba64f9 100644 --- a/gdb/testsuite/gdb.arch/amd64-prologue-skip-cf-protection.exp +++ b/gdb/testsuite/gdb.arch/i386-prologue-skip-cf-protection.exp @@ -16,13 +16,13 @@ # Test skipping a prologue that was generated with gcc's -fcf-protection=full # (control flow protection) option. # -# This option places an `endbr64` instruction at the start of all functions, -# which can interfere with prologue analysis. +# This option places an `endbr32`/`endbr64` instruction at the start of +# all functions, which can interfere with prologue analysis. standard_testfile .c set binfile ${binfile} -if { ![istarget x86_64-*-* ] || ![is_lp64_target] } { +if { ![istarget x86_64-*-*] && ![istarget i?86-*-*] } { verbose "Skipping ${testfile}." return } |