binutils: reproducibility: reuse debug-prefix-map for stabs

powerpc 32bit Linux Kernel widely uses .stabs pseudo-op to
produce debugging information in stabs format. Faced an issue
that during Linux Kernel build with Yocto build system for 32bit
powerpc platform resulting vmlinux contains absolute path in
.stabstr section that cannot be remapped with -fdebug-prefix-map
option.

Yocto uses scripts/mkmakefile Linux Kernel build approach that
allows to store all generated files outside of kernel source
tree. With this approach each compilier invocation is performed
with an absolute path to a file that will be compiled and this
absolute path is recorded in init stab. There is no way to remap
this path.

Reuse remap_debug_filename api to make -fdebug-prefix-map flag
aplicable for init stab.

(From OE-Core rev: 4dce4e01cfa153fb12cfd1684d36e0432bef6741)

Signed-off-by: Denys Zagorui <dzagorui@cisco.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 36 insertions, 0 deletions

diff --git a/meta/recipes-devtools/binutils/binutils-2.35.inc b/meta/recipes-devtools/binutils/binutils-2.35.inc
index 5ae9ec4226..bc9107b084 100644
--- a/meta/recipes-devtools/binutils/binutils-2.35.inc
+++ b/meta/recipes-devtools/binutils/binutils-2.35.inc
@@ -41,5 +41,6 @@ SRC_URI = "\
      file://0014-Fix-rpath-in-libtool-when-sysroot-is-enabled.patch \
      file://0015-sync-with-OE-libtool-changes.patch \
      file://0016-Check-for-clang-before-checking-gcc-version.patch \
+     file://0017-gas-improve-reproducibility-for-stabs-debugging-data.patch \
 "
 S  = "${WORKDIR}/git"
diff --git a/meta/recipes-devtools/binutils/binutils/0017-gas-improve-reproducibility-for-stabs-debugging-data.patch b/meta/recipes-devtools/binutils/binutils/0017-gas-improve-reproducibility-for-stabs-debugging-data.patch
new file mode 100644
index 0000000000..42e0c1c32d
--- /dev/null
+++ b/meta/recipes-devtools/binutils/binutils/0017-gas-improve-reproducibility-for-stabs-debugging-data.patch
@@ -0,0 +1,35 @@
+From aa6586e80fc6fcd739aa959a71e4cf064cdef072 Mon Sep 17 00:00:00 2001
+From: Denys Zagorui <dzagorui@cisco.com>
+Date: Mon, 9 Nov 2020 15:39:10 +0000
+Subject: [PATCH] gas: improve reproducibility for stabs debugging data format
+
+        * config/obj-elf (obj_elf_init_stab_section): Improve
+        reproducibility for stabs debugging data format
+
+Upstream-Status: Backport [https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=0541201782c006c09d029d18a45c6e743cfea906]
+---
+ gas/config/obj-elf.c | 3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/gas/config/obj-elf.c b/gas/config/obj-elf.c
+index de22b5a1da..2025df8542 100644
+--- a/gas/config/obj-elf.c
++++ b/gas/config/obj-elf.c
+@@ -2374,12 +2374,13 @@ obj_elf_init_stab_section (segT seg)
+   p = frag_more (12);
+   /* Zero it out.  */
+   memset (p, 0, 12);
+-  file = as_where (NULL);
++  file = remap_debug_filename (as_where (NULL));
+   stabstr_name = concat (segment_name (seg), "str", (char *) NULL);
+   stroff = get_stab_string_offset (file, stabstr_name, TRUE);
+   know (stroff == 1 || (stroff == 0 && file[0] == '\0'));
+   md_number_to_chars (p, stroff, 4);
+   seg_info (seg)->stabu.p = p;
++  xfree ((char *) file);
+ }
+ 
+ #endif
+-- 
+2.20.1
+