[PATCH 10/14] libdw: Try .dwp file in __libdw_find_split_unit()
Omar Sandoval
osandov@osandov.com
Wed Sep 27 18:20:59 GMT 2023
From: Omar Sandoval <osandov@fb.com>
Try opening the file in the location suggested by the standard (the
skeleton file name + ".dwp") and looking up the unit in the package
index. The rest is similar to .dwo files, with slightly different
cleanup since a single Dwarf handle is shared.
Signed-off-by: Omar Sandoval <osandov@fb.com>
---
libdw/ChangeLog | 11 ++++-
libdw/dwarf_begin_elf.c | 1 +
libdw/dwarf_cu_dwp_section_info.c | 19 ++++++++
libdw/dwarf_end.c | 10 ++++-
libdw/libdwP.h | 16 ++++++-
libdw/libdw_find_split_unit.c | 75 ++++++++++++++++++++++++++++---
6 files changed, 122 insertions(+), 10 deletions(-)
diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index f491587f..f37d9411 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,6 +1,8 @@
2023-09-27 Omar Sandoval <osandov@fb.com>
* libdw_find_split_unit.c (try_split_file): Make static.
+ (try_dwp_file): New function.
+ (__libdw_find_split_unit): Call try_dwp_file.
* dwarf_entrypc.c (dwarf_entrypc): Call dwarf_lowpc.
* dwarf_ranges.c (dwarf_ranges): Use skeleton ranges section for
skeleton units.
@@ -20,7 +22,8 @@
instead of dbg parameter, which is now unused.
* libdwP.h (Dwarf_Macro_Op_Table): Replace is_64bit with address_size
and offset_size. Add dbg.
- (Dwarf): Add cu_index and tu_index. Add elfpath.
+ (Dwarf): Add cu_index and tu_index. Add elfpath. Add dwp_dwarf and
+ dwp_fd.
(Dwarf_CU): Add dwp_row.
(Dwarf_Package_Index): New type.
(DW_SECT_TYPES): New macro.
@@ -31,6 +34,8 @@
(__libdw_debugdir): Replace declaration with...
(__libdw_elfpath): New declaration.
(__libdw_set_debugdir): New declaration.
+ (__libdw_dwp_findcu_id): New declaration.
+ (__libdw_link_skel_split): Handle .debug_addr for dwp.
* dwarf_begin_elf.c (dwarf_scnnames): Add IDX_debug_cu_index and
IDX_debug_tu_index.
(scn_to_string_section_idx): Ditto.
@@ -43,9 +48,11 @@
(__libdw_set_debugdir): New function.
(valid_p): Call __libdw_elfpath and __libdw_set_debugdir instead of
__libdw_debugdir.
+ (dwarf_begin_elf): Initialize result->dwp_fd.
* Makefile.am (libdw_a_SOURCES): Add dwarf_cu_dwp_section_info.c.
* dwarf_end.c (dwarf_end): Free dwarf->cu_index and dwarf->tu_index.
- Free dwarf->elfpath.
+ Free dwarf->elfpath. Free dwarf->dwp_dwarf and close dwarf->dwp_fd.
+ (cu_free): Don't free split dbg if it is dwp_dwarf.
* dwarf_error.c (errmsgs): Add DWARF_E_UNKNOWN_SECTION.
* libdw.h (dwarf_cu_dwp_section_info): New declaration.
* libdw.map (ELFUTILS_0.190): Add dwarf_cu_dwp_section_info.
diff --git a/libdw/dwarf_begin_elf.c b/libdw/dwarf_begin_elf.c
index 323a91d0..ca2b7e2a 100644
--- a/libdw/dwarf_begin_elf.c
+++ b/libdw/dwarf_begin_elf.c
@@ -567,6 +567,7 @@ dwarf_begin_elf (Elf *elf, Dwarf_Cmd cmd, Elf_Scn *scngrp)
result->elf = elf;
result->alt_fd = -1;
+ result->dwp_fd = -1;
/* Initialize the memory handling. Initial blocks are allocated on first
actual allocation. */
diff --git a/libdw/dwarf_cu_dwp_section_info.c b/libdw/dwarf_cu_dwp_section_info.c
index 6766fb9a..7bf08d9d 100644
--- a/libdw/dwarf_cu_dwp_section_info.c
+++ b/libdw/dwarf_cu_dwp_section_info.c
@@ -340,6 +340,25 @@ __libdw_dwp_find_unit (Dwarf *dbg, bool debug_types, Dwarf_Off off,
abbrev_offsetp, NULL);
}
+Dwarf_CU *
+internal_function
+__libdw_dwp_findcu_id (Dwarf *dbg, uint64_t unit_id8)
+{
+ Dwarf_Package_Index *index = __libdw_package_index (dbg, false);
+ uint32_t unit_row;
+ Dwarf_Off offset;
+ Dwarf_CU *cu;
+ if (__libdw_dwp_unit_row (index, unit_id8, &unit_row) == 0
+ && __libdw_dwp_section_info (index, unit_row, DW_SECT_INFO, &offset,
+ NULL) == 0
+ && (cu = __libdw_findcu (dbg, offset, false)) != NULL
+ && cu->unit_type == DW_UT_split_compile
+ && cu->unit_id8 == unit_id8)
+ return cu;
+ else
+ return NULL;
+}
+
int
dwarf_cu_dwp_section_info (Dwarf_CU *cu, unsigned int section,
Dwarf_Off *offsetp, Dwarf_Off *sizep)
diff --git a/libdw/dwarf_end.c b/libdw/dwarf_end.c
index b7f817d9..78224ddb 100644
--- a/libdw/dwarf_end.c
+++ b/libdw/dwarf_end.c
@@ -66,7 +66,9 @@ cu_free (void *arg)
/* The fake_addr_cu might be shared, only release one. */
if (p->dbg->fake_addr_cu == p->split->dbg->fake_addr_cu)
p->split->dbg->fake_addr_cu = NULL;
- INTUSE(dwarf_end) (p->split->dbg);
+ /* There is only one DWP file. We free it later. */
+ if (p->split->dbg != p->dbg->dwp_dwarf)
+ INTUSE(dwarf_end) (p->split->dbg);
}
}
}
@@ -147,6 +149,12 @@ dwarf_end (Dwarf *dwarf)
close (dwarf->alt_fd);
}
+ if (dwarf->dwp_fd != -1)
+ {
+ INTUSE(dwarf_end) (dwarf->dwp_dwarf);
+ close (dwarf->dwp_fd);
+ }
+
/* The cached path and dir we found the Dwarf ELF file in. */
free (dwarf->elfpath);
free (dwarf->debugdir);
diff --git a/libdw/libdwP.h b/libdw/libdwP.h
index 214d1711..16355274 100644
--- a/libdw/libdwP.h
+++ b/libdw/libdwP.h
@@ -180,6 +180,9 @@ struct Dwarf
/* dwz alternate DWARF file. */
Dwarf *alt_dwarf;
+ /* DWARF package file. */
+ Dwarf *dwp_dwarf;
+
/* The section data. */
Elf_Data *sectiondata[IDX_last];
@@ -197,6 +200,9 @@ struct Dwarf
close this file descriptor. */
int alt_fd;
+ /* File descriptor of DWARF package file. */
+ int dwp_fd;
+
/* Information for traversing the .debug_pubnames section. This is
an array and separately allocated with malloc. */
struct pubnames_s
@@ -719,6 +725,10 @@ extern int __libdw_dwp_find_unit (Dwarf *dbg, bool debug_types, Dwarf_Off off,
Dwarf_Off *abbrev_offsetp)
__nonnull_attribute__ (1, 7, 8) internal_function;
+/* Find the compilation unit in a DWARF package file with the given id. */
+extern Dwarf_CU *__libdw_dwp_findcu_id (Dwarf *dbg, uint64_t unit_id8)
+ __nonnull_attribute__ (1) internal_function;
+
/* Get abbreviation with given code. */
extern Dwarf_Abbrev *__libdw_findabbrev (struct Dwarf_CU *cu,
unsigned int code)
@@ -1373,8 +1383,10 @@ __libdw_link_skel_split (Dwarf_CU *skel, Dwarf_CU *split)
There is only one per split debug. */
Dwarf *dbg = skel->dbg;
Dwarf *sdbg = split->dbg;
- if (sdbg->sectiondata[IDX_debug_addr] == NULL
- && dbg->sectiondata[IDX_debug_addr] != NULL)
+ if (dbg->sectiondata[IDX_debug_addr] != NULL
+ && (sdbg->sectiondata[IDX_debug_addr] == NULL
+ || (sdbg->sectiondata[IDX_debug_addr]
+ == dbg->sectiondata[IDX_debug_addr])))
{
sdbg->sectiondata[IDX_debug_addr]
= dbg->sectiondata[IDX_debug_addr];
diff --git a/libdw/libdw_find_split_unit.c b/libdw/libdw_find_split_unit.c
index 533f8072..e1e78951 100644
--- a/libdw/libdw_find_split_unit.c
+++ b/libdw/libdw_find_split_unit.c
@@ -85,6 +85,67 @@ try_split_file (Dwarf_CU *cu, const char *dwo_path)
}
}
+static void
+try_dwp_file (Dwarf_CU *cu)
+{
+ if (cu->dbg->dwp_dwarf == NULL)
+ {
+ if (cu->dbg->elfpath != NULL)
+ {
+ /* The DWARF 5 standard says "the package file is typically placed in
+ the same directory as the application, and is given the same name
+ with a '.dwp' extension". */
+ size_t elfpath_len = strlen (cu->dbg->elfpath);
+ char *dwp_path = malloc (elfpath_len + 5);
+ if (dwp_path == NULL)
+ {
+ __libdw_seterrno (DWARF_E_NOMEM);
+ return;
+ }
+ memcpy (dwp_path, cu->dbg->elfpath, elfpath_len);
+ strcpy (dwp_path + elfpath_len, ".dwp");
+ int dwp_fd = open (dwp_path, O_RDONLY);
+ free (dwp_path);
+ if (dwp_fd != -1)
+ {
+ Dwarf *dwp_dwarf = dwarf_begin (dwp_fd, DWARF_C_READ);
+ /* There's no way to know whether we got the correct file until
+ we look up the unit, but it should at least be a dwp file. */
+ if (dwp_dwarf != NULL
+ && (dwp_dwarf->sectiondata[IDX_debug_cu_index] != NULL
+ || dwp_dwarf->sectiondata[IDX_debug_tu_index] != NULL))
+ {
+ cu->dbg->dwp_dwarf = dwp_dwarf;
+ cu->dbg->dwp_fd = dwp_fd;
+ }
+ else
+ close (dwp_fd);
+ }
+ }
+ if (cu->dbg->dwp_dwarf == NULL)
+ cu->dbg->dwp_dwarf = (Dwarf *) -1;
+ }
+
+ if (cu->dbg->dwp_dwarf != (Dwarf *) -1)
+ {
+ Dwarf_CU *split = __libdw_dwp_findcu_id (cu->dbg->dwp_dwarf,
+ cu->unit_id8);
+ if (split != NULL)
+ {
+ if (tsearch (split->dbg, &cu->dbg->split_tree,
+ __libdw_finddbg_cb) == NULL)
+ {
+ /* Something went wrong. Don't link. */
+ __libdw_seterrno (DWARF_E_NOMEM);
+ return;
+ }
+
+ /* Link skeleton and split compile units. */
+ __libdw_link_skel_split (cu, split);
+ }
+ }
+}
+
Dwarf_CU *
internal_function
__libdw_find_split_unit (Dwarf_CU *cu)
@@ -98,14 +159,18 @@ __libdw_find_split_unit (Dwarf_CU *cu)
same id as the skeleton. */
if (cu->unit_type == DW_UT_skeleton)
{
+ /* First, try the dwp file. */
+ try_dwp_file (cu);
+
Dwarf_Die cudie = CUDIE (cu);
Dwarf_Attribute dwo_name;
- /* It is fine if dwo_dir doesn't exists, but then dwo_name needs
- to be an absolute path. */
- if (dwarf_attr (&cudie, DW_AT_dwo_name, &dwo_name) != NULL
- || dwarf_attr (&cudie, DW_AT_GNU_dwo_name, &dwo_name) != NULL)
+ /* Try a dwo file. It is fine if dwo_dir doesn't exist, but then
+ dwo_name needs to be an absolute path. */
+ if (cu->split == (Dwarf_CU *) -1
+ && (dwarf_attr (&cudie, DW_AT_dwo_name, &dwo_name) != NULL
+ || dwarf_attr (&cudie, DW_AT_GNU_dwo_name, &dwo_name) != NULL))
{
- /* First try the dwo file name in the same directory
+ /* Try the dwo file name in the same directory
as we found the skeleton file. */
const char *dwo_file = dwarf_formstring (&dwo_name);
const char *debugdir = cu->dbg->debugdir;
--
2.41.0
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