[PATCH] x86: Pass "%s" to i386_dis_printf as the format string
Jan Beulich
jbeulich@suse.com
Sun May 24 15:11:43 GMT 2026
On 24.05.2026 02:09, H.J. Lu wrote:
> On Fri, May 15, 2026 at 9:08 PM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> Model this after operand handling, such that comments can be emitted in
>> the same order as operands. %rip-relative address comments remain
>> separate for now. While there correct style for the symbols associated
>> with immediates: These aren't "comment starts", but symbol names.
>> ---
>> As long as we want to continue to use the ->print_address_func() hook,
>> properly unifying %rip-relative comments with others won't be possible.
>> That, however, is in line with direct addresses also getting printed
>> specially, similarly by using ->print_address_func().
>>
>> Was it really intended for the original -Mannotate test to be run only for
>> Linux targets? It certainly isn't intended here, yet I'd like the new
>> tests to be in the same directory as the original one. x86-64.exp,
>> however, bails right away for non-Linux (and remote hosts). I guess at
>> least the *.d based testing loop should be moved up. Tests truly only
>> working for Linux can easily be constrained in the *.d files themselves.
>>
>> --- /dev/null
>> +++ b/binutils/testsuite/binutils-all/x86-64/comments.d
>> @@ -0,0 +1,14 @@
>> +#name: disassembly comments (AT&T)
>> +#ld:
>> +#objdump: -dwMannotate,att
>> +
>> +.*: +file format .*
>> +
>> +
>> +Disassembly of section .text:
>> +
>> +[0-9a-f]+ <_start>:
>> +[ ]*[0-9a-f]+: 48 c7 05 [0-9a-f ]+ movq \$0x[0-9a-f]+,0x[0-9a-f]+\(%rip\) +# \[_start\], [0-9a-f]+ <fptr>
>> +[ ]*[0-9a-f]+: 31 c0 xor %eax,%eax
>> +[ ]*[0-9a-f]+: c3 ret
>> +#pass
>> --- /dev/null
>> +++ b/binutils/testsuite/binutils-all/x86-64/comments.s
>> @@ -0,0 +1,9 @@
>> + .text
>> + .global _start
>> +_start:
>> + movq $_start, fptr(%rip)
>> + xor %eax, %eax
>> + ret
>> +
>> + .data
>> +fptr: .quad -1
>> --- /dev/null
>> +++ b/binutils/testsuite/binutils-all/x86-64/comments-intel.d
>> @@ -0,0 +1,14 @@
>> +#name: disassembly comments (Intel)
>> +#source: comments.s
>> +#ld:
>> +#objdump: -dwMannotate,intel
>> +
>> +.*: +file format .*
>> +
>> +
>> +Disassembly of section .text:
>> +
>> +[0-9a-f]+ <_start>:
>> +[ ]*[0-9a-f]+: 48 c7 05 [0-9a-f ]+ mov QWORD PTR \[rip\+0x[0-9a-f]+\],0x[0-9a-f]+ +# [0-9a-f]+ <fptr>, \[_start\]
>> +[ ]*[0-9a-f]+: 31 c0 xor eax,eax
>> +[ ]*[0-9a-f]+: c3 ret
>> --- a/opcodes/i386-dis.c
>> +++ b/opcodes/i386-dis.c
>> @@ -179,8 +179,7 @@ struct instr_info
>>
>> char obuf[MAX_OPERAND_BUFFER_SIZE];
>> char *obufp;
>> - char cbuf[COMMENT_BUFFER_SIZE];
>> - char * cbufp;
>> + char *cbufp;
>> char *mnemonicendp;
>> const uint8_t *start_codep;
>> uint8_t *codep;
>> @@ -258,6 +257,7 @@ struct instr_info
>> signed char op_index[MAX_OPERANDS];
>> bool op_riprel[MAX_OPERANDS];
>> char *op_out[MAX_OPERANDS];
>> + char *cm_out[MAX_OPERANDS];
>> bfd_vma op_address[MAX_OPERANDS];
>> bfd_vma start_pc;
>>
>> @@ -9749,7 +9749,6 @@ print_insn (bfd_vma pc, disassemble_info
>> .start_codep = priv.the_buffer,
>> .codep = priv.the_buffer,
>> .obufp = ins.obuf,
>> - .cbufp = ins.cbuf,
>> .last_lock_prefix = -1,
>> .last_repz_prefix = -1,
>> .last_repnz_prefix = -1,
>> @@ -9761,6 +9760,7 @@ print_insn (bfd_vma pc, disassemble_info
>> .fwait_prefix = -1,
>> };
>> char op_out[MAX_OPERANDS][MAX_OPERAND_BUFFER_SIZE];
>> + char cm_out[MAX_OPERANDS][COMMENT_BUFFER_SIZE];
>>
>> priv.orig_sizeflag = AFLAG | DFLAG;
>> if ((info->mach & bfd_mach_i386_i386) != 0)
>> @@ -9874,6 +9874,8 @@ print_insn (bfd_vma pc, disassemble_info
>> {
>> op_out[i][0] = 0;
>> ins.op_out[i] = op_out[i];
>> + cm_out[i][0] = 0;
>> + ins.cm_out[i] = cm_out[i];
>> }
>>
>> sizeflag = priv.orig_sizeflag;
>> @@ -9992,6 +9994,7 @@ print_insn (bfd_vma pc, disassemble_info
>> for (i = 0; i < MAX_OPERANDS; ++i)
>> {
>> ins.obufp = ins.op_out[i];
>> + ins.cbufp = ins.cm_out[i];
>> ins.op_ad = MAX_OPERANDS - 1 - i;
>> if (dp->op[i].rtn
>> && !dp->op[i].rtn (&ins, dp->op[i].bytemode, sizeflag))
>> @@ -10317,6 +10320,10 @@ print_insn (bfd_vma pc, disassemble_info
>> riprel = ins.op_riprel[i];
>> ins.op_riprel[i] = ins.op_riprel[MAX_OPERANDS - 1 - i];
>> ins.op_riprel[MAX_OPERANDS - 1 - i] = riprel;
>> +
>> + char *tmp = ins.cm_out[i];
>> + ins.cm_out[i] = ins.cm_out[MAX_OPERANDS - 1 - i];
>> + ins.cm_out[MAX_OPERANDS - 1 - i] = tmp;
>> }
>> }
>> else
>> @@ -10364,22 +10371,23 @@ print_insn (bfd_vma pc, disassemble_info
>> needcomma = 1;
>> }
>>
>> + const char *sep = " # ";
>> for (i = 0; i < MAX_OPERANDS; i++)
>> if (ins.op_index[i] != -1 && ins.op_riprel[i])
>> {
>> - i386_dis_printf (info, dis_style_comment_start, " # ");
>> + i386_dis_printf (info, dis_style_comment_start, sep);
>> + sep = ", ";
>> (*info->print_address_func)
>> ((bfd_vma)(ins.start_pc + (ins.codep - ins.start_codep)
>> + ins.op_address[ins.op_index[i]]),
>> - info);
>> - break;
>> + info);
>> + }
>> + else if (*ins.cm_out[i])
>> + {
>> + i386_dis_printf (info, dis_style_comment_start, sep);
>> + sep = ", ";
>> + i386_dis_printf (info, dis_style_symbol, "%s", ins.cm_out[i]);
>> }
>> - if (ins.cbufp != ins.cbuf)
>> - {
>> - if (i == MAX_OPERANDS)
>> - i386_dis_printf (info, dis_style_comment_start, " # ");
>> - i386_dis_printf (info, dis_style_comment_start, "%s", ins.cbuf);
>> - }
>>
>> ret = ins.codep - priv.the_buffer;
>> out:
>> @@ -10760,6 +10768,7 @@ dofloat (instr_info *ins, int sizeflag)
>
> commit aeced13ee0cd570d78cb37ab1f9bba840958515a
> Author: Jan Beulich <jbeulich@suse.com>
> Date: Fri May 22 08:49:12 2026 +0200
>
> x86/disasm: rework comment handling
>
> caused:
>
> libtool: compile: gcc -DHAVE_CONFIG_H -I. -I../../opcodes -I.
> -I../../opcodes -I../bfd -I../../opcodes/../include
> -I../../opcodes/../bfd -W -Wall -Wstrict-prototypes
> -Wmissing-prototypes -Wshadow -Wstack-usage=262144 -O2 -flto=auto
> -ffat-lto-objects -fexceptions -g -grecord-gcc-switches -pipe -Wall
> -Wno-complain-wrong-lang -Werror=format-security
> -Wp,-U_FORTIFY_SOURCE,-D_FORTIFY_SOURCE=3 -Wp,-D_GLIBCXX_ASSERTIONS
> -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1
> -fstack-protector-strong -specs=/usr/lib/rpm/redhat/redhat-annobin-cc1
> -m32 -march=i686 -mtune=generic -msse2 -mfpmath=sse -mstackrealign
> -fasynchronous-unwind-tables -fstack-clash-protection
> -mtls-dialect=gnu -flto=8 -std=gnu11 -fprofile-generate
> -flto=jobserver -ffat-lto-objects -MT i386-dis.lo -MD -MP -MF
> .deps/i386-dis.Tpo -c ../../opcodes/i386-dis.c -fPIC -DPIC -o
> .libs/i386-dis.o
> ../../opcodes/i386-dis.c: In function ‘print_insn’:
> ../../opcodes/i386-dis.c:10378:9: error: format not a string literal
> and no format arguments [-Werror=format-security]
> 10378 | i386_dis_printf (info, dis_style_comment_start, sep);
> | ^~~~~~~~~~~~~~~
> ../../opcodes/i386-dis.c:10387:9: error: format not a string literal
> and no format arguments [-Werror=format-security]
> 10387 | i386_dis_printf (info, dis_style_comment_start, sep);
> | ^~~~~~~~~~~~~~~
> cc1: some warnings being treated as errors
> make[4]: *** [Makefile:1076: i386-dis.lo] Error 1
>
> Since i386_dis_printf is declared as
>
> static void ATTRIBUTE_PRINTF_3 i386_dis_printf (const disassemble_info *,
> enum disassembler_style,
> const char *, ...);
>
> the 3rd argument should be a string literal as the format string. Pass
> "%s" to i386_dis_printf as the format string to fix the regression.
What exactly does "should" here mean? I.e. what exactly is wrong with the
format string not being a literal? Unless that can be explained, it feels as
if first of all a gcc bug wants opening. That would then want referencing
here.
Jan
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