git: dbf05458e3bd - main - libdwarf: Support consumption of compressed ELF sections
- Go to: [ bottom of page ] [ top of archives ] [ this month ]
Date: Mon, 06 Dec 2021 16:21:46 UTC
The branch main has been updated by markj:
URL: https://cgit.FreeBSD.org/src/commit/?id=dbf05458e3bd8c46f5e49918593557293a29d41a
commit dbf05458e3bd8c46f5e49918593557293a29d41a
Author: Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2021-12-06 15:37:49 +0000
Commit: Mark Johnston <markj@FreeBSD.org>
CommitDate: 2021-12-06 15:37:49 +0000
libdwarf: Support consumption of compressed ELF sections
Automatically decompress zlib-compressed debug sections when loading
them. This lets ctfcovert work on userland code after commit
c910570e7573 ("Use compressed debug in standalone userland debug files
by default").
Reported by: avg
Reviewed by: avg, emaste
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D33139
---
contrib/elftoolchain/libdwarf/_libdwarf.h | 5 +-
contrib/elftoolchain/libdwarf/libdwarf.h | 1 +
contrib/elftoolchain/libdwarf/libdwarf_elf_init.c | 87 +++++++++++++++++++----
lib/libdwarf/Makefile | 2 +-
share/mk/src.libnames.mk | 2 +-
5 files changed, 80 insertions(+), 17 deletions(-)
diff --git a/contrib/elftoolchain/libdwarf/_libdwarf.h b/contrib/elftoolchain/libdwarf/_libdwarf.h
index 6658d2d2f6f4..68a4c61522fa 100644
--- a/contrib/elftoolchain/libdwarf/_libdwarf.h
+++ b/contrib/elftoolchain/libdwarf/_libdwarf.h
@@ -379,8 +379,9 @@ typedef struct _Dwarf_Rel_Section {
} *Dwarf_Rel_Section;
typedef struct {
- Elf_Data *ed_data;
- void *ed_alloc;
+ Elf_Data *ed_data;
+ void *ed_alloc;
+ size_t ed_size; /* Uncompressed size. */
} Dwarf_Elf_Data;
typedef struct {
diff --git a/contrib/elftoolchain/libdwarf/libdwarf.h b/contrib/elftoolchain/libdwarf/libdwarf.h
index 6ec8f99c56a1..b1f9e0c8abc7 100644
--- a/contrib/elftoolchain/libdwarf/libdwarf.h
+++ b/contrib/elftoolchain/libdwarf/libdwarf.h
@@ -335,6 +335,7 @@ enum {
DW_DLE_ARANGE_OFFSET_BAD, /* Invalid arange offset. */
DW_DLE_DEBUG_MACRO_INCONSISTENT,/* Invalid macinfo data. */
DW_DLE_ELF_SECT_ERR, /* Application callback failed. */
+ DW_DLE_COMPRESSION, /* Section decompression error. */
DW_DLE_NUM /* Max error number. */
};
diff --git a/contrib/elftoolchain/libdwarf/libdwarf_elf_init.c b/contrib/elftoolchain/libdwarf/libdwarf_elf_init.c
index e304ef164157..c9b6ae601e0e 100644
--- a/contrib/elftoolchain/libdwarf/libdwarf_elf_init.c
+++ b/contrib/elftoolchain/libdwarf/libdwarf_elf_init.c
@@ -25,6 +25,7 @@
*/
#include "_libdwarf.h"
+#include <zlib.h>
ELFTC_VCSID("$Id: libdwarf_elf_init.c 3475 2016-05-18 18:11:26Z emaste $");
@@ -168,21 +169,28 @@ _dwarf_elf_relocate(Dwarf_Debug dbg, Elf *elf, Dwarf_Elf_Data *ed, size_t shndx,
return (DW_DLE_NONE);
}
- ed->ed_alloc = malloc(ed->ed_data->d_size);
+ /*
+ * A copy may already have been created if the section
+ * is compressed.
+ */
if (ed->ed_alloc == NULL) {
- DWARF_SET_ERROR(dbg, error, DW_DLE_MEMORY);
- return (DW_DLE_MEMORY);
+ ed->ed_alloc = malloc(ed->ed_size);
+ if (ed->ed_alloc == NULL) {
+ DWARF_SET_ERROR(dbg, error,
+ DW_DLE_MEMORY);
+ return (DW_DLE_MEMORY);
+ }
+ memcpy(ed->ed_alloc, ed->ed_data->d_buf,
+ ed->ed_size);
}
- memcpy(ed->ed_alloc, ed->ed_data->d_buf,
- ed->ed_data->d_size);
if (sh.sh_type == SHT_REL)
_dwarf_elf_apply_rel_reloc(dbg,
- ed->ed_alloc, ed->ed_data->d_size,
+ ed->ed_alloc, ed->ed_size,
rel, symtab_data, eh.e_ident[EI_DATA]);
else
_dwarf_elf_apply_rela_reloc(dbg,
- ed->ed_alloc, ed->ed_data->d_size,
- rel, symtab_data, eh.e_ident[EI_DATA]);
+ ed->ed_alloc, ed->ed_size, rel, symtab_data,
+ eh.e_ident[EI_DATA]);
return (DW_DLE_NONE);
}
@@ -196,13 +204,58 @@ _dwarf_elf_relocate(Dwarf_Debug dbg, Elf *elf, Dwarf_Elf_Data *ed, size_t shndx,
return (DW_DLE_NONE);
}
+static int
+_dwarf_elf_decompress(Dwarf_Debug dbg, Dwarf_Elf_Object *e, Elf_Scn *scn,
+ Dwarf_Elf_Data *ed, GElf_Shdr *shdr, Dwarf_Error *error)
+{
+ GElf_Chdr chdr;
+ size_t hsize;
+ unsigned long csize;
+
+ if (gelf_getchdr(scn, &chdr) == NULL) {
+ DWARF_SET_ELF_ERROR(dbg, error);
+ return (DW_DLE_ELF);
+ }
+
+ if (chdr.ch_type != ELFCOMPRESS_ZLIB) {
+ DWARF_SET_ERROR(dbg, error, DW_DLE_COMPRESSION);
+ return (DW_DLE_COMPRESSION);
+ }
+
+ if ((ed->ed_alloc = malloc(chdr.ch_size)) == NULL) {
+ DWARF_SET_ERROR(dbg, error, DW_DLE_MEMORY);
+ return (DW_DLE_MEMORY);
+ }
+
+ csize = chdr.ch_size;
+ hsize = e->eo_ehdr.e_ident[EI_CLASS] == ELFCLASS64 ?
+ sizeof(Elf64_Chdr) : sizeof(Elf32_Chdr);
+ if (uncompress(ed->ed_alloc, &csize, (char *)ed->ed_data->d_buf + hsize,
+ ed->ed_data->d_size - hsize) != Z_OK) {
+ DWARF_SET_ERROR(dbg, error, DW_DLE_COMPRESSION);
+ return (DW_DLE_COMPRESSION);
+ }
+ /* Sanity check. */
+ if (csize != chdr.ch_size) {
+ DWARF_SET_ERROR(dbg, error, DW_DLE_COMPRESSION);
+ return (DW_DLE_COMPRESSION);
+ }
+
+ ed->ed_size = chdr.ch_size;
+ shdr->sh_size = chdr.ch_size;
+ shdr->sh_addralign = chdr.ch_addralign;
+
+ return (DW_DLE_NONE);
+}
+
int
_dwarf_elf_init(Dwarf_Debug dbg, Elf *elf, Dwarf_Error *error)
{
Dwarf_Obj_Access_Interface *iface;
+ Dwarf_Elf_Data *ed;
Dwarf_Elf_Object *e;
const char *name;
- GElf_Shdr sh;
+ GElf_Shdr *es, sh;
Elf_Scn *scn;
Elf_Data *symtab_data;
size_t symtab_ndx;
@@ -319,8 +372,6 @@ _dwarf_elf_init(Dwarf_Debug dbg, Elf *elf, Dwarf_Error *error)
if (sh.sh_type == SHT_NOBITS)
continue;
- memcpy(&e->eo_shdr[j], &sh, sizeof(sh));
-
if ((name = elf_strptr(elf, e->eo_strndx, sh.sh_name)) ==
NULL) {
DWARF_SET_ELF_ERROR(dbg, error);
@@ -328,13 +379,15 @@ _dwarf_elf_init(Dwarf_Debug dbg, Elf *elf, Dwarf_Error *error)
goto fail_cleanup;
}
+ ed = &e->eo_data[j];
+ es = &e->eo_shdr[j];
+ memcpy(es, &sh, sizeof(sh));
for (i = 0; debug_name[i] != NULL; i++) {
if (strcmp(name, debug_name[i]))
continue;
(void) elf_errno();
- if ((e->eo_data[j].ed_data = elf_getdata(scn, NULL)) ==
- NULL) {
+ if ((ed->ed_data = elf_getdata(scn, NULL)) == NULL) {
elferr = elf_errno();
if (elferr != 0) {
_DWARF_SET_ERROR(dbg, error,
@@ -344,6 +397,14 @@ _dwarf_elf_init(Dwarf_Debug dbg, Elf *elf, Dwarf_Error *error)
}
}
+ if ((sh.sh_flags & SHF_COMPRESSED) != 0) {
+ if (_dwarf_elf_decompress(dbg, e, scn, ed,
+ es, error) != DW_DLE_NONE)
+ goto fail_cleanup;
+ } else {
+ ed->ed_size = ed->ed_data->d_size;
+ }
+
if (_libdwarf.applyreloc) {
if (_dwarf_elf_relocate(dbg, elf,
&e->eo_data[j], elf_ndxscn(scn), symtab_ndx,
diff --git a/lib/libdwarf/Makefile b/lib/libdwarf/Makefile
index 03f40cdd85ee..a3ef95b2572a 100644
--- a/lib/libdwarf/Makefile
+++ b/lib/libdwarf/Makefile
@@ -98,7 +98,7 @@ sys/elf32.h sys/elf64.h sys/elf_common.h: ${SRCTOP}/sys/${.TARGET} .NOMETA
mkdir -p ${.OBJDIR}/sys
ln -sf ${.ALLSRC} ${.TARGET}
-LIBADD+= elf
+LIBADD+= elf z
SHLIB_MAJOR= 4
diff --git a/share/mk/src.libnames.mk b/share/mk/src.libnames.mk
index bc3ad9c4bf40..23d09a434466 100644
--- a/share/mk/src.libnames.mk
+++ b/share/mk/src.libnames.mk
@@ -329,7 +329,7 @@ _DP_fetch= ssl crypto
_DP_fetch= md
.endif
_DP_execinfo= elf
-_DP_dwarf= elf
+_DP_dwarf= elf z
_DP_dpv= dialog figpar util tinfow ncursesw
_DP_dialog= tinfow ncursesw m
_DP_cuse= pthread