From: "Martin Liška" <mliska@suse.cz>
To: Fangrui Song <maskray@google.com>, binutils@sourceware.org
Cc: Alan Modra <amodra@gmail.com>
Subject: Re: [PATCH] readelf: support zstd compressed debug sections [PR 29640]
Date: Thu, 13 Oct 2022 13:38:42 +0200 [thread overview]
Message-ID: <45fca661-a0e8-f0f8-78d6-8d90783de6d7@suse.cz> (raw)
In-Reply-To: <20221001062057.681440-1-maskray@google.com>
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?
Cheers,
Martin
next prev parent reply other threads:[~2022-10-13 11:38 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 [this message]
2022-10-14 3:35 ` Fangrui Song
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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