From: Fangrui Song <maskray@google.com>
To: "Martin Liška" <mliska@suse.cz>
Cc: binutils@sourceware.org, Alan Modra <amodra@gmail.com>
Subject: Re: [PATCH] readelf: support zstd compressed debug sections [PR 29640]
Date: Thu, 13 Oct 2022 20:35:11 -0700 [thread overview]
Message-ID: <20221014033511.vqanebcqikmi5k37@google.com> (raw)
In-Reply-To: <45fca661-a0e8-f0f8-78d6-8d90783de6d7@suse.cz>
On 2022-10-13, Martin Liška wrote:
>On 10/1/22 08:20, Fangrui Song wrote:
>> ---
>> binutils/Makefile.am | 6 +--
>> binutils/Makefile.in | 6 +--
>> binutils/readelf.c | 112 +++++++++++++++++++++++++++----------------
>> 3 files changed, 78 insertions(+), 46 deletions(-)
>>
>> diff --git a/binutils/Makefile.am b/binutils/Makefile.am
>> index 751fbacce12..b249af721ae 100644
>> --- a/binutils/Makefile.am
>> +++ b/binutils/Makefile.am
>> @@ -54,8 +54,8 @@ DEBUGINFOD_LIBS = @DEBUGINFOD_LIBS@
>> WARN_CFLAGS = @WARN_CFLAGS@
>> WARN_CFLAGS_FOR_BUILD = @WARN_CFLAGS_FOR_BUILD@
>> NO_WERROR = @NO_WERROR@
>> -AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC)
>> -AM_CFLAGS_FOR_BUILD = $(WARN_CFLAGS_FOR_BUILD) $(ZLIBINC)
>> +AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC) $(ZSTD_CFLAGS)
>> +AM_CFLAGS_FOR_BUILD = $(WARN_CFLAGS_FOR_BUILD) $(ZLIBINC) $(ZSTD_CFLAGS)
>> LIBICONV = @LIBICONV@
>>
>> # these two are almost the same program
>> @@ -256,7 +256,7 @@ objcopy_SOURCES = objcopy.c not-strip.c rename.c $(WRITE_DEBUG_SRCS) $(BULIBS)
>> strings_SOURCES = strings.c $(BULIBS)
>>
>> readelf_SOURCES = readelf.c version.c unwind-ia64.c dwarf.c demanguse.c $(ELFLIBS)
>> -readelf_LDADD = $(LIBCTF_NOBFD) $(LIBINTL) $(LIBIBERTY) $(ZLIB) $(DEBUGINFOD_LIBS) $(MSGPACK_LIBS)
>> +readelf_LDADD = $(LIBCTF_NOBFD) $(LIBINTL) $(LIBIBERTY) $(ZLIB) $(ZSTD_LIBS) $(DEBUGINFOD_LIBS) $(MSGPACK_LIBS)
>>
>> elfedit_SOURCES = elfedit.c version.c $(ELFLIBS)
>> elfedit_LDADD = $(LIBINTL) $(LIBIBERTY)
>> diff --git a/binutils/Makefile.in b/binutils/Makefile.in
>> index 6de4e239408..7d9039e0f2f 100644
>> --- a/binutils/Makefile.in
>> +++ b/binutils/Makefile.in
>> @@ -651,8 +651,8 @@ am__skipyacc =
>> # case both are empty.
>> ZLIB = @zlibdir@ -lz
>> ZLIBINC = @zlibinc@
>> -AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC)
>> -AM_CFLAGS_FOR_BUILD = $(WARN_CFLAGS_FOR_BUILD) $(ZLIBINC)
>> +AM_CFLAGS = $(WARN_CFLAGS) $(ZLIBINC) $(ZSTD_CFLAGS)
>> +AM_CFLAGS_FOR_BUILD = $(WARN_CFLAGS_FOR_BUILD) $(ZLIBINC) $(ZSTD_CFLAGS)
>>
>> # these two are almost the same program
>> AR_PROG = ar
>> @@ -790,7 +790,7 @@ size_SOURCES = size.c $(BULIBS)
>> objcopy_SOURCES = objcopy.c not-strip.c rename.c $(WRITE_DEBUG_SRCS) $(BULIBS)
>> strings_SOURCES = strings.c $(BULIBS)
>> readelf_SOURCES = readelf.c version.c unwind-ia64.c dwarf.c demanguse.c $(ELFLIBS)
>> -readelf_LDADD = $(LIBCTF_NOBFD) $(LIBINTL) $(LIBIBERTY) $(ZLIB) $(DEBUGINFOD_LIBS) $(MSGPACK_LIBS)
>> +readelf_LDADD = $(LIBCTF_NOBFD) $(LIBINTL) $(LIBIBERTY) $(ZLIB) $(ZSTD_LIBS) $(DEBUGINFOD_LIBS) $(MSGPACK_LIBS)
>> elfedit_SOURCES = elfedit.c version.c $(ELFLIBS)
>> elfedit_LDADD = $(LIBINTL) $(LIBIBERTY)
>> strip_new_SOURCES = objcopy.c is-strip.c rename.c $(WRITE_DEBUG_SRCS) $(BULIBS)
>> diff --git a/binutils/readelf.c b/binutils/readelf.c
>> index 351571c8abb..04cda213f33 100644
>> --- a/binutils/readelf.c
>> +++ b/binutils/readelf.c
>> @@ -44,6 +44,9 @@
>> #include <assert.h>
>> #include <time.h>
>> #include <zlib.h>
>> +#ifdef HAVE_ZSTD
>> +#include <zstd.h>
>> +#endif
>> #include <wchar.h>
>>
>> #if defined HAVE_MSGPACK
>> @@ -15170,48 +15173,56 @@ get_section_contents (Elf_Internal_Shdr * section, Filedata * filedata)
>> _("section contents"));
>> }
>>
>> -/* Uncompresses a section that was compressed using zlib, in place. */
>> +/* Uncompresses a section that was compressed using zlib/zstd, in place. */
>>
>> static bool
>> -uncompress_section_contents (unsigned char **buffer,
>> - uint64_t uncompressed_size,
>> - uint64_t *size)
>> +uncompress_section_contents (bool is_zstd, unsigned char **buffer,
>> + uint64_t uncompressed_size, uint64_t *size)
>> {
>> uint64_t compressed_size = *size;
>> unsigned char *compressed_buffer = *buffer;
>> - unsigned char *uncompressed_buffer;
>> + unsigned char *uncompressed_buffer = xmalloc (uncompressed_size);
>> z_stream strm;
>> int rc;
>>
>> - /* It is possible the section consists of several compressed
>> - buffers concatenated together, so we uncompress in a loop. */
>> - /* PR 18313: The state field in the z_stream structure is supposed
>> - to be invisible to the user (ie us), but some compilers will
>> - still complain about it being used without initialisation. So
>> - we first zero the entire z_stream structure and then set the fields
>> - that we need. */
>> - memset (& strm, 0, sizeof strm);
>> - strm.avail_in = compressed_size;
>> - strm.next_in = (Bytef *) compressed_buffer;
>> - strm.avail_out = uncompressed_size;
>> - uncompressed_buffer = (unsigned char *) xmalloc (uncompressed_size);
>> + if (is_zstd)
>> + {
>> +#ifdef HAVE_ZSTD
>> + size_t ret = ZSTD_decompress (uncompressed_buffer, uncompressed_size,
>> + compressed_buffer, compressed_size);
>> + if (ZSTD_isError (ret))
>> + goto fail;
>> +#endif
>> + }
>> + else
>> + {
>> + /* It is possible the section consists of several compressed
>> + buffers concatenated together, so we uncompress in a loop. */
>> + /* PR 18313: The state field in the z_stream structure is supposed
>> + to be invisible to the user (ie us), but some compilers will
>> + still complain about it being used without initialisation. So
>> + we first zero the entire z_stream structure and then set the fields
>> + that we need. */
>> + memset (&strm, 0, sizeof strm);
>> + strm.avail_in = compressed_size;
>> + strm.next_in = (Bytef *)compressed_buffer;
>> + strm.avail_out = uncompressed_size;
>>
>> - rc = inflateInit (& strm);
>> - while (strm.avail_in > 0)
>> - {
>> - if (rc != Z_OK)
>> - break;
>> - strm.next_out = ((Bytef *) uncompressed_buffer
>> - + (uncompressed_size - strm.avail_out));
>> - rc = inflate (&strm, Z_FINISH);
>> - if (rc != Z_STREAM_END)
>> - break;
>> - rc = inflateReset (& strm);
>> + rc = inflateInit (&strm);
>> + while (strm.avail_in > 0)
>> + {
>> + if (rc != Z_OK)
>> + break;
>> + strm.next_out = ((Bytef *)uncompressed_buffer
>> + + (uncompressed_size - strm.avail_out));
>> + rc = inflate (&strm, Z_FINISH);
>> + if (rc != Z_STREAM_END)
>> + break;
>> + rc = inflateReset (&strm);
>> + }
>> + if (inflateEnd (&strm) != Z_OK || rc != Z_OK || strm.avail_out != 0)
>> + goto fail;
>> }
>> - if (inflateEnd (& strm) != Z_OK
>> - || rc != Z_OK
>> - || strm.avail_out != 0)
>> - goto fail;
>>
>> *buffer = uncompressed_buffer;
>> *size = uncompressed_size;
>> @@ -15254,6 +15265,7 @@ dump_section_as_strings (Elf_Internal_Shdr * section, Filedata * filedata)
>> {
>> uint64_t new_size = num_bytes;
>> uint64_t uncompressed_size = 0;
>> + bool is_zstd = false;
>>
>> if ((section->sh_flags & SHF_COMPRESSED) != 0)
>> {
>> @@ -15266,7 +15278,13 @@ dump_section_as_strings (Elf_Internal_Shdr * section, Filedata * filedata)
>> by get_compression_header. */
>> goto error_out;
>>
>> - if (chdr.ch_type != ELFCOMPRESS_ZLIB)
>> + if (chdr.ch_type == ELFCOMPRESS_ZLIB)
>> + ;
>> +#ifdef HAVE_ZSTD
>> + else if (chdr.ch_type == ELFCOMPRESS_ZSTD)
>> + is_zstd = true;
>> +#endif
>> + else
>> {
>> warn (_("section '%s' has unsupported compress type: %d\n"),
>> printable_section_name (filedata, section), chdr.ch_type);
>> @@ -15295,8 +15313,8 @@ dump_section_as_strings (Elf_Internal_Shdr * section, Filedata * filedata)
>>
>> if (uncompressed_size)
>> {
>> - if (uncompress_section_contents (& start,
>> - uncompressed_size, & new_size))
>> + if (uncompress_section_contents (is_zstd, &start, uncompressed_size,
>> + &new_size))
>> num_bytes = new_size;
>> else
>> {
>> @@ -15470,6 +15488,7 @@ dump_section_as_bytes (Elf_Internal_Shdr *section,
>> {
>> uint64_t new_size = section_size;
>> uint64_t uncompressed_size = 0;
>> + bool is_zstd = false;
>>
>> if ((section->sh_flags & SHF_COMPRESSED) != 0)
>> {
>> @@ -15482,7 +15501,13 @@ dump_section_as_bytes (Elf_Internal_Shdr *section,
>> by get_compression_header. */
>> goto error_out;
>>
>> - if (chdr.ch_type != ELFCOMPRESS_ZLIB)
>> + if (chdr.ch_type == ELFCOMPRESS_ZLIB)
>> + ;
>> +#ifdef HAVE_ZSTD
>> + else if (chdr.ch_type == ELFCOMPRESS_ZSTD)
>> + is_zstd = true;
>> +#endif
>> + else
>> {
>> warn (_("section '%s' has unsupported compress type: %d\n"),
>> printable_section_name (filedata, section), chdr.ch_type);
>> @@ -15511,8 +15536,8 @@ dump_section_as_bytes (Elf_Internal_Shdr *section,
>>
>> if (uncompressed_size)
>> {
>> - if (uncompress_section_contents (& start, uncompressed_size,
>> - & new_size))
>> + if (uncompress_section_contents (is_zstd, &start, uncompressed_size,
>> + &new_size))
>> {
>> section_size = new_size;
>> }
>> @@ -15848,6 +15873,7 @@ load_specific_debug_section (enum dwarf_section_display_enum debug,
>> unsigned char *start = section->start;
>> uint64_t size = sec->sh_size;
>> uint64_t uncompressed_size = 0;
>> + bool is_zstd = false;
>>
>> if ((sec->sh_flags & SHF_COMPRESSED) != 0)
>> {
>> @@ -15869,7 +15895,13 @@ load_specific_debug_section (enum dwarf_section_display_enum debug,
>> by get_compression_header. */
>> return false;
>>
>> - if (chdr.ch_type != ELFCOMPRESS_ZLIB)
>> + if (chdr.ch_type == ELFCOMPRESS_ZLIB)
>> + ;
>> +#ifdef HAVE_ZSTD
>> + else if (chdr.ch_type == ELFCOMPRESS_ZSTD)
>> + is_zstd = true;
>> +#endif
>> + else
>> {
>> warn (_("section '%s' has unsupported compress type: %d\n"),
>> section->name, chdr.ch_type);
>> @@ -15898,7 +15930,7 @@ load_specific_debug_section (enum dwarf_section_display_enum debug,
>>
>> if (uncompressed_size)
>> {
>> - if (uncompress_section_contents (&start, uncompressed_size,
>> + if (uncompress_section_contents (is_zstd, &start, uncompressed_size,
>> &size))
>> {
>> /* Free the compressed buffer, update the section buffer
>
>Hi.
>
>I noticed the following issue (dunno if caused by objcopy or the patches readelf) with this patch:
>
>$ echo 'int main() {return 0;}' | gcc -O2 -g -c -o a.o -x c -
>$ /home/marxin/Programming/binutils/objdir/ld/../binutils/objcopy -O elf32-x86-64 a.o a-x32.o --compress-debug-sections=zstd
>$ /home/marxin/Programming/binutils/objdir/binutils/readelf -wi a-x32.o >/dev/null
>readelf: Error: Unable to decompress section .debug_info
>readelf: Error: No comp units in .debug_info section ?
>
>while zlib is fine:
>
>$ /home/marxin/Programming/binutils/objdir/ld/../binutils/objcopy -O elf32-x86-64 a.o a-x32.o --compress-debug-sections=zlib
>$ /home/marxin/Programming/binutils/objdir/binutils/readelf -wi a-x32.o >/dev/null
>
>Can you please take a look?
objcopy -O elf32-x86-64 a.o a-x32.o --compress-debug-sections=zstd uses
ch_type=1 (ELFCOMPRESS_ZLIB), but I don't know where goes wrong.
Converting EI_CLASS looks very hacky to me.
next prev parent reply other threads:[~2022-10-14 3:35 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-01 6:20 Fangrui Song
2022-10-06 2:20 ` Fangrui Song
2022-10-20 8:04 ` Martin Liška
2022-10-20 8:05 ` Martin Liška
2022-10-13 11:38 ` Martin Liška
2022-10-14 3:35 ` Fangrui Song [this message]
2022-10-14 7:47 ` Martin Liška
2022-10-14 8:26 ` Martin Liška
2022-10-14 11:28 ` Alan Modra
2022-10-14 12:09 ` Alan Modra
2022-10-16 4:42 ` Alan Modra
2022-10-16 20:46 ` Fangrui Song
2022-10-21 9:16 ` Alan Modra
2022-10-17 7:52 ` Martin Liška
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