[RFC 0/2] libbacktrace: add FDPIC support

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* [RFC 0/2] libbacktrace: add FDPIC support
@ 2024-05-27  6:50 Max Filippov
  2024-05-27  6:50 ` [RFC 1/2] " Max Filippov
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Max Filippov @ 2024-05-27  6:50 UTC (permalink / raw)
  To: gcc-patches; +Cc: Ian Lance Taylor, Max Filippov

This is an RFC series that adds FDPIC ELF target support to
libbacktrace.

While debugging this I've noticed that there's no unwinding info for the
libstdc++ version of libbacktrace, which made backtraces empty for me,
both on xtensa-linux-uclibcfdpic and on regular xtensa-linux-uclibc.
Adding -funwind-tables to the libstdc++ version of libbacktrace fixed
that. Which makes me wonder how it works for other architectures?

Max Filippov (2):
  libbacktrace: add FDPIC support
  libstdc++-v3/src/libbacktrace: add -funwind-tables

 libbacktrace/dwarf.c                      | 60 ++++++++++++++---------
 libbacktrace/elf.c                        | 20 +++++---
 libbacktrace/internal.h                   | 14 +++++-
 libstdc++-v3/src/libbacktrace/Makefile.am |  4 +-
 libstdc++-v3/src/libbacktrace/Makefile.in |  4 +-
 5 files changed, 66 insertions(+), 36 deletions(-)

-- 
2.39.2

^ permalink raw reply	[flat|nested] 6+ messages in thread

* [RFC 1/2] libbacktrace: add FDPIC support
  2024-05-27  6:50 [RFC 0/2] libbacktrace: add FDPIC support Max Filippov
@ 2024-05-27  6:50 ` Max Filippov
  2024-06-11 16:54   ` Max Filippov
  2024-05-27  6:50 ` [RFC 2/2] libstdc++-v3/src/libbacktrace: add -funwind-tables Max Filippov
  2024-05-27  7:01 ` [RFC 0/2] libbacktrace: add FDPIC support Rainer Orth
  2 siblings, 1 reply; 6+ messages in thread
From: Max Filippov @ 2024-05-27  6:50 UTC (permalink / raw)
  To: gcc-patches; +Cc: Ian Lance Taylor, Max Filippov

Instead of a single base address FDPIC ELF files use load map: a
structure with an array of mappings for individual segments.  Change
libbacktrace functions and structures to support that.

libbacktrace/

	PR libbacktrace/114941
	* dwarf.c: Include <link.h> or <sys/link.h> if available.
	(struct dwarf_data): Change base_address type to base_address_type.
	(add_low_high_range): Change base_address argument type to
	base_address_type.  Use __RELOC_UINTPTR for lowpc and highpc
	calculation.
	(add_ranges_from_ranges): Change base_address argument type to
	base_address_type.  Use __RELOC_UINTPTR to calculate arguments
	for add_range().
	(add_ranges_from_rnglists): Change base_address argument type to
	base_address_type.  Use __RELOC_UINTPTR to calculate arguments
	for add_range().  Use __RELOC_UINTPTR for low calculation.
	(add_ranges, find_address_ranges, build_address_map): Change
	base_address argument type to base_address_type.
	(add_line): Use __RELOC_UINTPTR for ln->pc calculation.
	(build_dwarf_data, backtrace_dwarf_add): Change base_address
	argument type to base_address_type.
	* elf.c (elf_initialize_syminfo): Change base_address argument
	type to base_address_type.  Use __RELOC_UINTPTR for
	elf_symbols[j].address calculation.
	(elf_add): Change base_address argument type to
	base_address_type.  Do early return -1 in case of FDPIC
	executable, update corresponding comment.
	(backtrace_initialize): Change NULL base address parameter in
	the add_elf() call to no_base_address.
	* internal.h (base_address_type, __RELOC_POINTER)
	(__RELOC_UINTPTR, no_base_address): New definitions.
	(backtrace_dwarf_add): Change base_address argument type to
	base_address_type.
---
 libbacktrace/dwarf.c    | 60 ++++++++++++++++++++++++-----------------
 libbacktrace/elf.c      | 20 +++++++++-----
 libbacktrace/internal.h | 14 +++++++++-
 3 files changed, 62 insertions(+), 32 deletions(-)

diff --git a/libbacktrace/dwarf.c b/libbacktrace/dwarf.c
index ed0672964c24..bcab23562e2a 100644
--- a/libbacktrace/dwarf.c
+++ b/libbacktrace/dwarf.c
@@ -43,6 +43,15 @@ POSSIBILITY OF SUCH DAMAGE.  */
 #include "backtrace.h"
 #include "internal.h"
 
+#ifdef __FDPIC__
+ #ifdef HAVE_LINK_H
+  #include <link.h>
+ #endif
+ #ifdef HAVE_SYS_LINK_H
+  #include <sys/link.h>
+ #endif
+#endif
+
 #if !defined(HAVE_DECL_STRNLEN) || !HAVE_DECL_STRNLEN
 
 /* If strnlen is not declared, provide our own version.  */
@@ -389,7 +398,7 @@ struct dwarf_data
   /* The data for .gnu_debugaltlink.  */
   struct dwarf_data *altlink;
   /* The base address for this file.  */
-  uintptr_t base_address;
+  base_address_type base_address;
   /* A sorted list of address ranges.  */
   struct unit_addrs *addrs;
   /* Number of address ranges in list.  */
@@ -1610,7 +1619,7 @@ update_pcrange (const struct attr* attr, const struct attr_val* val,
 static int
 add_low_high_range (struct backtrace_state *state,
 		    const struct dwarf_sections *dwarf_sections,
-		    uintptr_t base_address, int is_bigendian,
+		    base_address_type base_address, int is_bigendian,
 		    struct unit *u, const struct pcrange *pcrange,
 		    int (*add_range) (struct backtrace_state *state,
 				      void *rdata, uintptr_t lowpc,
@@ -1646,8 +1655,8 @@ add_low_high_range (struct backtrace_state *state,
 
   /* Add in the base address of the module when recording PC values,
      so that we can look up the PC directly.  */
-  lowpc += base_address;
-  highpc += base_address;
+  lowpc = __RELOC_UINTPTR (lowpc, base_address);
+  highpc = __RELOC_UINTPTR (highpc, base_address);
 
   return add_range (state, rdata, lowpc, highpc, error_callback, data, vec);
 }
@@ -1659,7 +1668,7 @@ static int
 add_ranges_from_ranges (
     struct backtrace_state *state,
     const struct dwarf_sections *dwarf_sections,
-    uintptr_t base_address, int is_bigendian,
+    base_address_type base_address, int is_bigendian,
     struct unit *u, uintptr_t base,
     const struct pcrange *pcrange,
     int (*add_range) (struct backtrace_state *state, void *rdata,
@@ -1706,8 +1715,8 @@ add_ranges_from_ranges (
       else
 	{
 	  if (!add_range (state, rdata, 
-			  (uintptr_t) low + base + base_address,
-			  (uintptr_t) high + base + base_address,
+			  __RELOC_UINTPTR (low + base, base_address),
+			  __RELOC_UINTPTR (high + base, base_address),
 			  error_callback, data, vec))
 	    return 0;
 	}
@@ -1726,7 +1735,7 @@ static int
 add_ranges_from_rnglists (
     struct backtrace_state *state,
     const struct dwarf_sections *dwarf_sections,
-    uintptr_t base_address, int is_bigendian,
+    base_address_type base_address, int is_bigendian,
     struct unit *u, uintptr_t base,
     const struct pcrange *pcrange,
     int (*add_range) (struct backtrace_state *state, void *rdata,
@@ -1809,9 +1818,9 @@ add_ranges_from_rnglists (
 				     u->addrsize, is_bigendian, index,
 				     error_callback, data, &high))
 	      return 0;
-	    if (!add_range (state, rdata, low + base_address,
-			    high + base_address, error_callback, data,
-			    vec))
+	    if (!add_range (state, rdata, __RELOC_UINTPTR (low, base_address),
+			    __RELOC_UINTPTR (high, base_address),
+			    error_callback, data, vec))
 	      return 0;
 	  }
 	  break;
@@ -1828,7 +1837,7 @@ add_ranges_from_rnglists (
 				     error_callback, data, &low))
 	      return 0;
 	    length = read_uleb128 (&rnglists_buf);
-	    low += base_address;
+	    low = __RELOC_UINTPTR (low, base_address);
 	    if (!add_range (state, rdata, low, low + length,
 			    error_callback, data, vec))
 	      return 0;
@@ -1842,8 +1851,9 @@ add_ranges_from_rnglists (
 
 	    low = read_uleb128 (&rnglists_buf);
 	    high = read_uleb128 (&rnglists_buf);
-	    if (!add_range (state, rdata, low + base + base_address,
-			    high + base + base_address,
+	    if (!add_range (state, rdata,
+			    __RELOC_UINTPTR (low + base, base_address),
+			    __RELOC_UINTPTR (high + base, base_address),
 			    error_callback, data, vec))
 	      return 0;
 	  }
@@ -1860,9 +1870,9 @@ add_ranges_from_rnglists (
 
 	    low = (uintptr_t) read_address (&rnglists_buf, u->addrsize);
 	    high = (uintptr_t) read_address (&rnglists_buf, u->addrsize);
-	    if (!add_range (state, rdata, low + base_address,
-			    high + base_address, error_callback, data,
-			    vec))
+	    if (!add_range (state, rdata, __RELOC_UINTPTR (low, base_address),
+			    __RELOC_UINTPTR (high, base_address),
+			    error_callback, data, vec))
 	      return 0;
 	  }
 	  break;
@@ -1874,7 +1884,7 @@ add_ranges_from_rnglists (
 
 	    low = (uintptr_t) read_address (&rnglists_buf, u->addrsize);
 	    length = (uintptr_t) read_uleb128 (&rnglists_buf);
-	    low += base_address;
+	    low = __RELOC_UINTPTR (low, base_address);
 	    if (!add_range (state, rdata, low, low + length,
 			    error_callback, data, vec))
 	      return 0;
@@ -1902,7 +1912,7 @@ add_ranges_from_rnglists (
 static int
 add_ranges (struct backtrace_state *state,
 	    const struct dwarf_sections *dwarf_sections,
-	    uintptr_t base_address, int is_bigendian,
+	    base_address_type base_address, int is_bigendian,
 	    struct unit *u, uintptr_t base, const struct pcrange *pcrange,
 	    int (*add_range) (struct backtrace_state *state, void *rdata, 
 			      uintptr_t lowpc, uintptr_t highpc,
@@ -1938,7 +1948,8 @@ add_ranges (struct backtrace_state *state,
    read, 0 if there is some error.  */
 
 static int
-find_address_ranges (struct backtrace_state *state, uintptr_t base_address,
+find_address_ranges (struct backtrace_state *state,
+		     base_address_type base_address,
 		     struct dwarf_buf *unit_buf,
 		     const struct dwarf_sections *dwarf_sections,
 		     int is_bigendian, struct dwarf_data *altlink,
@@ -2093,7 +2104,8 @@ find_address_ranges (struct backtrace_state *state, uintptr_t base_address,
    on success, 0 on failure.  */
 
 static int
-build_address_map (struct backtrace_state *state, uintptr_t base_address,
+build_address_map (struct backtrace_state *state,
+		   base_address_type base_address,
 		   const struct dwarf_sections *dwarf_sections,
 		   int is_bigendian, struct dwarf_data *altlink,
 		   backtrace_error_callback error_callback, void *data,
@@ -2312,7 +2324,7 @@ add_line (struct backtrace_state *state, struct dwarf_data *ddata,
 
   /* Add in the base address here, so that we can look up the PC
      directly.  */
-  ln->pc = pc + ddata->base_address;
+  ln->pc = __RELOC_UINTPTR (pc, ddata->base_address);
 
   ln->filename = filename;
   ln->lineno = lineno;
@@ -3951,7 +3963,7 @@ dwarf_fileline (struct backtrace_state *state, uintptr_t pc,
 
 static struct dwarf_data *
 build_dwarf_data (struct backtrace_state *state,
-		  uintptr_t base_address,
+		  base_address_type base_address,
 		  const struct dwarf_sections *dwarf_sections,
 		  int is_bigendian,
 		  struct dwarf_data *altlink,
@@ -4009,7 +4021,7 @@ build_dwarf_data (struct backtrace_state *state,
 
 int
 backtrace_dwarf_add (struct backtrace_state *state,
-		     uintptr_t base_address,
+		     base_address_type base_address,
 		     const struct dwarf_sections *dwarf_sections,
 		     int is_bigendian,
 		     struct dwarf_data *fileline_altlink,
diff --git a/libbacktrace/elf.c b/libbacktrace/elf.c
index 3cd87020b031..c2d18b4a398e 100644
--- a/libbacktrace/elf.c
+++ b/libbacktrace/elf.c
@@ -633,7 +633,7 @@ elf_symbol_search (const void *vkey, const void *ventry)
 
 static int
 elf_initialize_syminfo (struct backtrace_state *state,
-			uintptr_t base_address,
+			base_address_type base_address,
 			const unsigned char *symtab_data, size_t symtab_size,
 			const unsigned char *strtab, size_t strtab_size,
 			backtrace_error_callback error_callback,
@@ -699,7 +699,7 @@ elf_initialize_syminfo (struct backtrace_state *state,
 	  = *(const b_elf_addr *) (opd->data + (sym->st_value - opd->addr));
       else
 	elf_symbols[j].address = sym->st_value;
-      elf_symbols[j].address += base_address;
+      elf_symbols[j].address = __RELOC_UINTPTR (elf_symbols[j].address, base_address);
       elf_symbols[j].size = sym->st_size;
       ++j;
     }
@@ -6506,7 +6506,7 @@ backtrace_uncompress_lzma (struct backtrace_state *state,
 static int
 elf_add (struct backtrace_state *state, const char *filename, int descriptor,
 	 const unsigned char *memory, size_t memory_size,
-	 uintptr_t base_address, struct elf_ppc64_opd_data *caller_opd,
+	 base_address_type base_address, struct elf_ppc64_opd_data *caller_opd,
 	 backtrace_error_callback error_callback, void *data,
 	 fileline *fileline_fn, int *found_sym, int *found_dwarf,
 	 struct dwarf_data **fileline_entry, int exe, int debuginfo,
@@ -6636,9 +6636,15 @@ elf_add (struct backtrace_state *state, const char *filename, int descriptor,
 
   /* If the executable is ET_DYN, it is either a PIE, or we are running
      directly a shared library with .interp.  We need to wait for
-     dl_iterate_phdr in that case to determine the actual base_address.  */
+     dl_iterate_phdr in that case to determine the actual base_address.
+     In case of FDPIC we always need the actual base_address.  */
+#ifndef __FDPIC__
   if (exe && ehdr.e_type == ET_DYN)
     return -1;
+#else
+  if (exe)
+    return -1;
+#endif
 
   shoff = ehdr.e_shoff;
   shnum = ehdr.e_shnum;
@@ -7413,9 +7419,9 @@ backtrace_initialize (struct backtrace_state *state, const char *filename,
   fileline elf_fileline_fn = elf_nodebug;
   struct phdr_data pd;
 
-  ret = elf_add (state, filename, descriptor, NULL, 0, 0, NULL, error_callback,
-		 data, &elf_fileline_fn, &found_sym, &found_dwarf, NULL, 1, 0,
-		 NULL, 0);
+  ret = elf_add (state, filename, descriptor, NULL, 0, no_base_address, NULL,
+		 error_callback, data, &elf_fileline_fn, &found_sym,
+		 &found_dwarf, NULL, 1, 0, NULL, 0);
   if (!ret)
     return 0;
 
diff --git a/libbacktrace/internal.h b/libbacktrace/internal.h
index 4fa0af8cb6c9..456911166026 100644
--- a/libbacktrace/internal.h
+++ b/libbacktrace/internal.h
@@ -323,10 +323,22 @@ struct dwarf_sections
 
 struct dwarf_data;
 
+#if defined (HAVE_DL_ITERATE_PHDR) && defined (__FDPIC__)
+typedef struct elf32_fdpic_loadaddr base_address_type;
+#define __RELOC_UINTPTR(ptr, base) ((uintptr_t)__RELOC_POINTER (ptr, base))
+#define no_base_address ((struct elf32_fdpic_loadaddr){0})
+#else
+typedef uintptr_t base_address_type;
+#define __RELOC_POINTER(ptr, base) ((ptr) + (base))
+#define __RELOC_UINTPTR(ptr, base) ((uintptr_t)__RELOC_POINTER (ptr, base))
+#define no_base_address ((uintptr_t)0)
+#endif
+
+
 /* Add file/line information for a DWARF module.  */
 
 extern int backtrace_dwarf_add (struct backtrace_state *state,
-				uintptr_t base_address,
+				base_address_type base_address,
 				const struct dwarf_sections *dwarf_sections,
 				int is_bigendian,
 				struct dwarf_data *fileline_altlink,
-- 
2.39.2


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [RFC 1/2] libbacktrace: add FDPIC support
  2024-05-27  6:50 ` [RFC 1/2] " Max Filippov
@ 2024-06-11 16:54   ` Max Filippov
  0 siblings, 0 replies; 6+ messages in thread
From: Max Filippov @ 2024-06-11 16:54 UTC (permalink / raw)
  To: gcc-patches; +Cc: Ian Lance Taylor

On Sun, May 26, 2024 at 11:50 PM Max Filippov <jcmvbkbc@gmail.com> wrote:
>
> Instead of a single base address FDPIC ELF files use load map: a
> structure with an array of mappings for individual segments.  Change
> libbacktrace functions and structures to support that.

Ping?

> libbacktrace/
>
>         PR libbacktrace/114941
>         * dwarf.c: Include <link.h> or <sys/link.h> if available.
>         (struct dwarf_data): Change base_address type to base_address_type.
>         (add_low_high_range): Change base_address argument type to
>         base_address_type.  Use __RELOC_UINTPTR for lowpc and highpc
>         calculation.
>         (add_ranges_from_ranges): Change base_address argument type to
>         base_address_type.  Use __RELOC_UINTPTR to calculate arguments
>         for add_range().
>         (add_ranges_from_rnglists): Change base_address argument type to
>         base_address_type.  Use __RELOC_UINTPTR to calculate arguments
>         for add_range().  Use __RELOC_UINTPTR for low calculation.
>         (add_ranges, find_address_ranges, build_address_map): Change
>         base_address argument type to base_address_type.
>         (add_line): Use __RELOC_UINTPTR for ln->pc calculation.
>         (build_dwarf_data, backtrace_dwarf_add): Change base_address
>         argument type to base_address_type.
>         * elf.c (elf_initialize_syminfo): Change base_address argument
>         type to base_address_type.  Use __RELOC_UINTPTR for
>         elf_symbols[j].address calculation.
>         (elf_add): Change base_address argument type to
>         base_address_type.  Do early return -1 in case of FDPIC
>         executable, update corresponding comment.
>         (backtrace_initialize): Change NULL base address parameter in
>         the add_elf() call to no_base_address.
>         * internal.h (base_address_type, __RELOC_POINTER)
>         (__RELOC_UINTPTR, no_base_address): New definitions.
>         (backtrace_dwarf_add): Change base_address argument type to
>         base_address_type.
> ---
>  libbacktrace/dwarf.c    | 60 ++++++++++++++++++++++++-----------------
>  libbacktrace/elf.c      | 20 +++++++++-----
>  libbacktrace/internal.h | 14 +++++++++-
>  3 files changed, 62 insertions(+), 32 deletions(-)

-- 
Thanks.
-- Max

^ permalink raw reply	[flat|nested] 6+ messages in thread

* [RFC 2/2] libstdc++-v3/src/libbacktrace: add -funwind-tables
  2024-05-27  6:50 [RFC 0/2] libbacktrace: add FDPIC support Max Filippov
  2024-05-27  6:50 ` [RFC 1/2] " Max Filippov
@ 2024-05-27  6:50 ` Max Filippov
  2024-05-27  7:01 ` [RFC 0/2] libbacktrace: add FDPIC support Rainer Orth
  2 siblings, 0 replies; 6+ messages in thread
From: Max Filippov @ 2024-05-27  6:50 UTC (permalink / raw)
  To: gcc-patches; +Cc: Ian Lance Taylor, Max Filippov

libstdc++-v3/

	* src/libbacktrace/Makefile.am (AM_CFLAGS, AM_CXXFLAGS): Add
	-funwind-tables
	* src/libbacktrace/Makefile.in: Regenerate.
---
 libstdc++-v3/src/libbacktrace/Makefile.am | 4 ++--
 libstdc++-v3/src/libbacktrace/Makefile.in | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/libstdc++-v3/src/libbacktrace/Makefile.am b/libstdc++-v3/src/libbacktrace/Makefile.am
index a2e786712593..ecc0be7c305c 100644
--- a/libstdc++-v3/src/libbacktrace/Makefile.am
+++ b/libstdc++-v3/src/libbacktrace/Makefile.am
@@ -51,11 +51,11 @@ C_WARN_FLAGS = $(WARN_FLAGS) -Wstrict-prototypes -Wmissing-prototypes -Wold-styl
 CXX_WARN_FLAGS = $(WARN_FLAGS) -Wno-unused-parameter
 AM_CFLAGS = \
 	$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
-	$(C_WARN_FLAGS)
+	-funwind-tables $(C_WARN_FLAGS)
 AM_CFLAGS += $(EXTRA_CFLAGS)
 AM_CXXFLAGS = \
 	$(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
-	$(CXX_WARN_FLAGS) -fno-rtti -fno-exceptions
+	-funwind-tables $(CXX_WARN_FLAGS) -fno-rtti -fno-exceptions
 AM_CXXFLAGS += $(EXTRA_CXXFLAGS)
 
 obj_prefix = std_stacktrace
diff --git a/libstdc++-v3/src/libbacktrace/Makefile.in b/libstdc++-v3/src/libbacktrace/Makefile.in
index b5713b0c616e..eec6b36d8cbd 100644
--- a/libstdc++-v3/src/libbacktrace/Makefile.in
+++ b/libstdc++-v3/src/libbacktrace/Makefile.in
@@ -473,9 +473,9 @@ libstdc___libbacktrace_la_CPPFLAGS = \
 C_WARN_FLAGS = $(WARN_FLAGS) -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wno-unused-but-set-variable
 CXX_WARN_FLAGS = $(WARN_FLAGS) -Wno-unused-parameter
 AM_CFLAGS = $(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
-	$(C_WARN_FLAGS) $(EXTRA_CFLAGS)
+	-funwind-tables $(C_WARN_FLAGS) $(EXTRA_CFLAGS)
 AM_CXXFLAGS = $(glibcxx_lt_pic_flag) $(glibcxx_compiler_shared_flag) \
-	$(CXX_WARN_FLAGS) -fno-rtti -fno-exceptions $(EXTRA_CXXFLAGS)
+	-funwind-tables $(CXX_WARN_FLAGS) -fno-rtti -fno-exceptions $(EXTRA_CXXFLAGS)
 obj_prefix = std_stacktrace
 
 # Each FILE.c in SOURCES will be compiled to SHORTNAME-FILE.o
-- 
2.39.2


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [RFC 0/2] libbacktrace: add FDPIC support
  2024-05-27  6:50 [RFC 0/2] libbacktrace: add FDPIC support Max Filippov
  2024-05-27  6:50 ` [RFC 1/2] " Max Filippov
  2024-05-27  6:50 ` [RFC 2/2] libstdc++-v3/src/libbacktrace: add -funwind-tables Max Filippov
@ 2024-05-27  7:01 ` Rainer Orth
  2024-05-27  7:12   ` Max Filippov
  2 siblings, 1 reply; 6+ messages in thread
From: Rainer Orth @ 2024-05-27  7:01 UTC (permalink / raw)
  To: Max Filippov; +Cc: gcc-patches, Ian Lance Taylor

Hi Max,

> This is an RFC series that adds FDPIC ELF target support to
> libbacktrace.
>
> While debugging this I've noticed that there's no unwinding info for the
> libstdc++ version of libbacktrace, which made backtraces empty for me,
> both on xtensa-linux-uclibcfdpic and on regular xtensa-linux-uclibc.
> Adding -funwind-tables to the libstdc++ version of libbacktrace fixed
> that. Which makes me wonder how it works for other architectures?

it doesn't ;-(  See PR libstdc++/111641 for details.  There's a patch in
there, too.

	Rainer

-- 
-----------------------------------------------------------------------------
Rainer Orth, Center for Biotechnology, Bielefeld University

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: [RFC 0/2] libbacktrace: add FDPIC support
  2024-05-27  7:01 ` [RFC 0/2] libbacktrace: add FDPIC support Rainer Orth
@ 2024-05-27  7:12   ` Max Filippov
  0 siblings, 0 replies; 6+ messages in thread
From: Max Filippov @ 2024-05-27  7:12 UTC (permalink / raw)
  To: Rainer Orth; +Cc: gcc-patches, Ian Lance Taylor

On Mon, May 27, 2024 at 12:01 AM Rainer Orth
<ro@cebitec.uni-bielefeld.de> wrote:
> > This is an RFC series that adds FDPIC ELF target support to
> > libbacktrace.
> >
> > While debugging this I've noticed that there's no unwinding info for the
> > libstdc++ version of libbacktrace, which made backtraces empty for me,
> > both on xtensa-linux-uclibcfdpic and on regular xtensa-linux-uclibc.
> > Adding -funwind-tables to the libstdc++ version of libbacktrace fixed
> > that. Which makes me wonder how it works for other architectures?
>
> it doesn't ;-(  See PR libstdc++/111641 for details.  There's a patch in
> there, too.

Oh, cool, thanks for the pointer Rainer. So patch 2 of this series can be
disregarded.

-- 
Thanks.
-- Max

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2024-06-11 16:54 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2024-05-27  6:50 [RFC 0/2] libbacktrace: add FDPIC support Max Filippov
2024-05-27  6:50 ` [RFC 1/2] " Max Filippov
2024-06-11 16:54   ` Max Filippov
2024-05-27  6:50 ` [RFC 2/2] libstdc++-v3/src/libbacktrace: add -funwind-tables Max Filippov
2024-05-27  7:01 ` [RFC 0/2] libbacktrace: add FDPIC support Rainer Orth
2024-05-27  7:12   ` Max Filippov

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