* [binutils-gdb] x86: last-insn recording should be per-section
@ 2023-12-01 7:29 Jan Beulich
0 siblings, 0 replies; only message in thread
From: Jan Beulich @ 2023-12-01 7:29 UTC (permalink / raw)
To: bfd-cvs
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b5482fe535884c9fdb5c45c5627ec99e54c0e9d9
commit b5482fe535884c9fdb5c45c5627ec99e54c0e9d9
Author: Jan Beulich <jbeulich@suse.com>
Date: Fri Dec 1 08:27:22 2023 +0100
x86: last-insn recording should be per-section
Otherwise intermediate section switches result in inconsistent behavior.
Note, however, that intermediate sub-section switches will continue to
result in inconsistent or even inappropriate behavior.
While there also add recording of state to s_insn().
Diff:
---
gas/config/tc-i386.c | 105 ++++++++++++++------------------
gas/config/tc-i386.h | 17 ++++++
gas/testsuite/gas/i386/i386.exp | 11 ++++
gas/testsuite/gas/i386/lfence-section.d | 19 ++++++
gas/testsuite/gas/i386/lfence-section.e | 3 +
gas/testsuite/gas/i386/lfence-section.s | 19 ++++++
6 files changed, 116 insertions(+), 58 deletions(-)
diff --git a/gas/config/tc-i386.c b/gas/config/tc-i386.c
index b1cd0e4542f..059dd49feea 100644
--- a/gas/config/tc-i386.c
+++ b/gas/config/tc-i386.c
@@ -178,7 +178,7 @@ static int check_word_reg (void);
static int finalize_imm (void);
static int process_operands (void);
static const reg_entry *build_modrm_byte (void);
-static void output_insn (void);
+static void output_insn (const struct last_insn *);
static void output_imm (fragS *, offsetT);
static void output_disp (fragS *, offsetT);
#ifndef I386COFF
@@ -677,21 +677,6 @@ static enum lfence_before_ret_kind
}
lfence_before_ret;
-/* Types of previous instruction is .byte or prefix. */
-static struct
- {
- segT seg;
- const char *file;
- const char *name;
- unsigned int line;
- enum last_insn_kind
- {
- last_insn_other = 0,
- last_insn_directive,
- last_insn_prefix
- } kind;
- } last_insn;
-
/* 1 if the assembler should generate relax relocations. */
static int generate_relax_relocations
@@ -4971,7 +4956,7 @@ insert_lfence_after (void)
/* Output lfence, 0xfaee8, before instruction. */
static void
-insert_lfence_before (void)
+insert_lfence_before (const struct last_insn *last_insn)
{
char *p;
@@ -5007,12 +4992,11 @@ insert_lfence_before (void)
else
return;
- if (last_insn.kind != last_insn_other
- && last_insn.seg == now_seg)
+ if (last_insn->kind != last_insn_other)
{
- as_warn_where (last_insn.file, last_insn.line,
+ as_warn_where (last_insn->file, last_insn->line,
_("`%s` skips -mlfence-before-indirect-branch on `%s`"),
- last_insn.name, insn_name (&i.tm));
+ last_insn->name, insn_name (&i.tm));
return;
}
@@ -5027,12 +5011,11 @@ insert_lfence_before (void)
if (lfence_before_ret != lfence_before_ret_none
&& (i.tm.base_opcode | 1) == 0xc3)
{
- if (last_insn.kind != last_insn_other
- && last_insn.seg == now_seg)
+ if (last_insn->kind != last_insn_other)
{
- as_warn_where (last_insn.file, last_insn.line,
+ as_warn_where (last_insn->file, last_insn->line,
_("`%s` skips -mlfence-before-ret on `%s`"),
- last_insn.name, insn_name (&i.tm));
+ last_insn->name, insn_name (&i.tm));
return;
}
@@ -5129,6 +5112,8 @@ md_assemble (char *line)
const char *end, *pass1_mnem = NULL;
enum i386_error pass1_err = 0;
const insn_template *t;
+ struct last_insn *last_insn
+ = &seg_info(now_seg)->tc_segment_info_data.last_insn;
/* Initialize globals. */
current_templates.end = current_templates.start = NULL;
@@ -5682,23 +5667,21 @@ md_assemble (char *line)
if (i.rex != 0)
add_prefix (REX_OPCODE | i.rex);
- insert_lfence_before ();
+ insert_lfence_before (last_insn);
/* We are ready to output the insn. */
- output_insn ();
+ output_insn (last_insn);
insert_lfence_after ();
- last_insn.seg = now_seg;
-
if (i.tm.opcode_modifier.isprefix)
{
- last_insn.kind = last_insn_prefix;
- last_insn.name = insn_name (&i.tm);
- last_insn.file = as_where (&last_insn.line);
+ last_insn->kind = last_insn_prefix;
+ last_insn->name = insn_name (&i.tm);
+ last_insn->file = as_where (&last_insn->line);
}
else
- last_insn.kind = last_insn_other;
+ last_insn->kind = last_insn_other;
}
/* The Q suffix is generally valid only in 64-bit mode, with very few
@@ -9667,7 +9650,8 @@ maybe_fused_with_jcc_p (enum mf_cmp_kind* mf_cmp_p)
/* Return 1 if a FUSED_JCC_PADDING frag should be generated. */
static int
-add_fused_jcc_padding_frag_p (enum mf_cmp_kind* mf_cmp_p)
+add_fused_jcc_padding_frag_p (enum mf_cmp_kind *mf_cmp_p,
+ const struct last_insn *last_insn)
{
/* NB: Don't work with COND_JUMP86 without i386. */
if (!align_branch_power
@@ -9678,13 +9662,12 @@ add_fused_jcc_padding_frag_p (enum mf_cmp_kind* mf_cmp_p)
if (maybe_fused_with_jcc_p (mf_cmp_p))
{
- if (last_insn.kind == last_insn_other
- || last_insn.seg != now_seg)
+ if (last_insn->kind == last_insn_other)
return 1;
if (flag_debug)
- as_warn_where (last_insn.file, last_insn.line,
+ as_warn_where (last_insn->file, last_insn->line,
_("`%s` skips -malign-branch-boundary on `%s`"),
- last_insn.name, insn_name (&i.tm));
+ last_insn->name, insn_name (&i.tm));
}
return 0;
@@ -9693,7 +9676,7 @@ add_fused_jcc_padding_frag_p (enum mf_cmp_kind* mf_cmp_p)
/* Return 1 if a BRANCH_PREFIX frag should be generated. */
static int
-add_branch_prefix_frag_p (void)
+add_branch_prefix_frag_p (const struct last_insn *last_insn)
{
/* NB: Don't work with COND_JUMP86 without i386. Don't add prefix
to PadLock instructions since they include prefixes in opcode. */
@@ -9709,14 +9692,13 @@ add_branch_prefix_frag_p (void)
if (!i.operands || i.tm.opcode_modifier.isprefix)
return 0;
- if (last_insn.kind == last_insn_other
- || last_insn.seg != now_seg)
+ if (last_insn->kind == last_insn_other)
return 1;
if (flag_debug)
- as_warn_where (last_insn.file, last_insn.line,
+ as_warn_where (last_insn->file, last_insn->line,
_("`%s` skips -malign-branch-boundary on `%s`"),
- last_insn.name, insn_name (&i.tm));
+ last_insn->name, insn_name (&i.tm));
return 0;
}
@@ -9725,7 +9707,8 @@ add_branch_prefix_frag_p (void)
static int
add_branch_padding_frag_p (enum align_branch_kind *branch_p,
- enum mf_jcc_kind *mf_jcc_p)
+ enum mf_jcc_kind *mf_jcc_p,
+ const struct last_insn *last_insn)
{
int add_padding;
@@ -9799,13 +9782,12 @@ add_branch_padding_frag_p (enum align_branch_kind *branch_p,
}
if (add_padding
- && last_insn.kind != last_insn_other
- && last_insn.seg == now_seg)
+ && last_insn->kind != last_insn_other)
{
if (flag_debug)
- as_warn_where (last_insn.file, last_insn.line,
+ as_warn_where (last_insn->file, last_insn->line,
_("`%s` skips -malign-branch-boundary on `%s`"),
- last_insn.name, insn_name (&i.tm));
+ last_insn->name, insn_name (&i.tm));
return 0;
}
@@ -9813,7 +9795,7 @@ add_branch_padding_frag_p (enum align_branch_kind *branch_p,
}
static void
-output_insn (void)
+output_insn (const struct last_insn *last_insn)
{
fragS *insn_start_frag;
offsetT insn_start_off;
@@ -9943,7 +9925,7 @@ output_insn (void)
insn_start_frag = frag_now;
insn_start_off = frag_now_fix ();
- if (add_branch_padding_frag_p (&branch, &mf_jcc))
+ if (add_branch_padding_frag_p (&branch, &mf_jcc, last_insn))
{
char *p;
/* Branch can be 8 bytes. Leave some room for prefixes. */
@@ -10029,7 +10011,7 @@ output_insn (void)
if (branch)
/* Skip if this is a branch. */
;
- else if (add_fused_jcc_padding_frag_p (&mf_cmp))
+ else if (add_fused_jcc_padding_frag_p (&mf_cmp, last_insn))
{
/* Make room for padding. */
frag_grow (MAX_FUSED_JCC_PADDING_SIZE);
@@ -10045,7 +10027,7 @@ output_insn (void)
fragP->tc_frag_data.branch_type = align_branch_fused;
fragP->tc_frag_data.max_bytes = MAX_FUSED_JCC_PADDING_SIZE;
}
- else if (add_branch_prefix_frag_p ())
+ else if (add_branch_prefix_frag_p (last_insn))
{
unsigned int max_prefix_size = align_branch_prefix_size;
@@ -10948,6 +10930,7 @@ s_insn (int dummy ATTRIBUTE_UNUSED)
unsigned int j;
valueT val;
bool vex = false, xop = false, evex = false;
+ struct last_insn *last_insn;
init_globals ();
@@ -11701,7 +11684,11 @@ s_insn (int dummy ATTRIBUTE_UNUSED)
else if (i.rex != 0)
add_prefix (REX_OPCODE | i.rex);
- output_insn ();
+ last_insn = &seg_info(now_seg)->tc_segment_info_data.last_insn;
+ output_insn (last_insn);
+ last_insn->kind = last_insn_directive;
+ last_insn->name = ".insn directive";
+ last_insn->file = as_where (&last_insn->line);
done:
*saved_ilp = saved_char;
@@ -15496,13 +15483,15 @@ s_bss (int ignore ATTRIBUTE_UNUSED)
void
i386_cons_align (int ignore ATTRIBUTE_UNUSED)
{
- if (last_insn.kind != last_insn_directive
+ struct last_insn *last_insn
+ = &seg_info(now_seg)->tc_segment_info_data.last_insn;
+
+ if (last_insn->kind != last_insn_directive
&& (bfd_section_flags (now_seg) & SEC_CODE))
{
- last_insn.seg = now_seg;
- last_insn.kind = last_insn_directive;
- last_insn.name = "constant directive";
- last_insn.file = as_where (&last_insn.line);
+ last_insn->kind = last_insn_directive;
+ last_insn->name = "constant directive";
+ last_insn->file = as_where (&last_insn->line);
if (lfence_before_ret != lfence_before_ret_none)
{
if (lfence_before_indirect_branch != lfence_branch_none)
diff --git a/gas/config/tc-i386.h b/gas/config/tc-i386.h
index 5db25087290..c3022149fbe 100644
--- a/gas/config/tc-i386.h
+++ b/gas/config/tc-i386.h
@@ -281,6 +281,23 @@ extern enum i386_flag_code {
CODE_64BIT
} i386_flag_code;
+struct i386_segment_info {
+ /* Type of previous "instruction", e.g. .byte or stand-alone prefix. */
+ struct last_insn {
+ const char *file;
+ const char *name;
+ unsigned int line;
+ enum last_insn_kind
+ {
+ last_insn_other = 0,
+ last_insn_directive,
+ last_insn_prefix
+ } kind;
+ } last_insn;
+};
+
+#define TC_SEGMENT_INFO_TYPE struct i386_segment_info
+
struct i386_tc_frag_data
{
union
diff --git a/gas/testsuite/gas/i386/i386.exp b/gas/testsuite/gas/i386/i386.exp
index 6ab197089ee..2c2543daa14 100644
--- a/gas/testsuite/gas/i386/i386.exp
+++ b/gas/testsuite/gas/i386/i386.exp
@@ -642,6 +642,17 @@ if [gas_32_check] then {
run_dump_test "lfence-ret-c"
run_dump_test "lfence-ret-d"
run_dump_test "lfence-byte"
+ # This test uses the .section directive, which only ELF and COFF/PE support.
+ if {[is_elf_format]
+ || [istarget "*-*-vxworks*"]
+ || [istarget "*-*-coff*"]
+ || [istarget "*-*-pe*"]
+ || [istarget "*-*-cygwin*"]
+ || [istarget "*-*-mingw*"]
+ } then {
+ run_dump_test "lfence-section"
+ }
+
run_dump_test "branch"
# These tests require support for 8 and 16 bit relocs,
diff --git a/gas/testsuite/gas/i386/lfence-section.d b/gas/testsuite/gas/i386/lfence-section.d
new file mode 100644
index 00000000000..830851c3fc7
--- /dev/null
+++ b/gas/testsuite/gas/i386/lfence-section.d
@@ -0,0 +1,19 @@
+#as: -mlfence-before-indirect-branch=all
+#warning_output: lfence-section.e
+#objdump: -dw
+#name: -mlfence-before-indirect-branch=all w/ section switches
+
+.*: +file format .*
+
+
+Disassembly of section .text:
+
+0+ <_start>:
+ +[a-f0-9]+: f3 ff d0 repz call \*%eax
+ +[a-f0-9]+: f3 c3 repz ret
+ +[a-f0-9]+: cc int3
+ +[a-f0-9]+: cc int3
+ +[a-f0-9]+: cc int3
+
+Disassembly of section \.text2:
+#pass
diff --git a/gas/testsuite/gas/i386/lfence-section.e b/gas/testsuite/gas/i386/lfence-section.e
new file mode 100644
index 00000000000..47f5b2b91c0
--- /dev/null
+++ b/gas/testsuite/gas/i386/lfence-section.e
@@ -0,0 +1,3 @@
+.*: Assembler messages:
+.*:3: Warning: `rep` skips -mlfence-before-indirect-branch on `call`
+.*:11: Warning: `rep` skips -mlfence-before-ret on `ret`
diff --git a/gas/testsuite/gas/i386/lfence-section.s b/gas/testsuite/gas/i386/lfence-section.s
new file mode 100644
index 00000000000..bc3dd0bc7cc
--- /dev/null
+++ b/gas/testsuite/gas/i386/lfence-section.s
@@ -0,0 +1,19 @@
+ .text
+_start:
+ rep
+
+ .section .text2, "ax"
+aux1:
+ nop
+
+ .text
+ call *%eax
+ rep
+
+ .section .text2, "ax"
+aux2:
+ nop
+
+ .text
+ ret
+ .p2align 2, 0xcc
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