[binutils-gdb] libsframe: use proper FRE type when flipping SFrame V3 FREs

[Jens Remus]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=9f3749fff938e51ed1a1d92b308a363b2f8197ce

commit 9f3749fff938e51ed1a1d92b308a363b2f8197ce
Author: Jens Remus <jremus@linux.ibm.com>
Date:   Tue Jan 20 10:22:52 2026 +0100

    libsframe: use proper FRE type when flipping SFrame V3 FREs
    
    flip_sframe_fdes_with_fres_v3 was erroneously using a fixed FRE type
    of 0 (= SFRAME_FRE_TYPE_ADDR1) when endianness byte-flipping the FREs,
    regardless of the actual FRE type (i.e. ADDR1, ADDR2, or ADDR4).  This
    only affected cross builds, where the .sframe section data may needed
    to be endianness byte-flipped (e.g. binutils cross-built for s390
    64-bit (s390x) on x86-64).
    
    As a consequence objdump/readelf with option --sframe could fail to dump
    e.g. s390 64-bit (s390x) .sframe section data on x86-64 with the
    following error message:
    
      Error: SFrame decode failure: Buffer does not contain SFrame data.
    
    The linker ld-sframe test "PR ld/33401 (Step 1: Create relocatable
    object and check R_*_NONE)" cross-build for s390 64-bit (s390x) on
    x86-64 could fail with ld error message:
    
      error in tmpdir/StatePlaying.o(.sframe); no .sframe will be created
    
    The linker ld-sframe test "PR ld/33401 (Step 1: Create relocatable
    object and check R_*_NONE)" cros-build for s390 64-bit (s390x) on
    x86-64 could fail with BDF assertion:
    
      BFD (GNU Binutils) ... assertion fail .../bfd/elf-sframe.c:153
    
    Add a common cfi-sframe assembler test, that forces a FDE type of
    SFRAME_FRE_TYPE_ADDR2.  When the test is run cross-build it may
    exercise the SFrame FDE and FDE endianness byte flipping.
    
    libsframe/
            PR ld/33810
            * sframe.c (sframe_decode_fde_attr_v3): Decode and return FRE
            type from FDE attributes.
            (flip_sframe_fdes_with_fres_v3): Use proper FRE type from
            FDE attributes when flipping FREs.
    
    gas/testsuite/
            PR ld/33810
            * gas/cfi-sframe/cfi-sframe.exp (cfi-sframe-common-pr33810): Run
            new test.
            * gas/cfi-sframe/cfi-sframe-common-pr33810.d: New test.
            * gas/cfi-sframe/cfi-sframe-common-pr33810.s: Likewise.
    
    Bug: https://sourceware.org/pr33810
    Fixes: 8ab6e4c72ab6 ("[SFrame-V3] include: gas: libsframe: split FDE into idx and attr")
    Reported-by: Alan Modra <amodra@gmail.com>
    Signed-off-by: Jens Remus <jremus@linux.ibm.com>

Diff:
---
 .../gas/cfi-sframe/cfi-sframe-common-pr33810.d     | 23 ++++++++++++++++++++++
 .../gas/cfi-sframe/cfi-sframe-common-pr33810.s     |  7 +++++++
 gas/testsuite/gas/cfi-sframe/cfi-sframe.exp        |  2 ++
 libsframe/sframe.c                                 | 13 ++++++------
 4 files changed, 38 insertions(+), 7 deletions(-)

diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-common-pr33810.d b/gas/testsuite/gas/cfi-sframe/cfi-sframe-common-pr33810.d
new file mode 100644
index 00000000000..ae8b76a6eff
--- /dev/null
+++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-common-pr33810.d
@@ -0,0 +1,23 @@
+#as: --gsframe
+#objdump: --sframe=.sframe
+#name: SFrame FRE type SFRAME_FRE_TYPE_ADDR2 (PR 33810)
+#...
+Contents of the SFrame section .sframe:
+
+  Header :
+
+    Version: SFRAME_VERSION_3
+    Flags: SFRAME_F_FDE_FUNC_START_PCREL
+#?    CFA fixed FP offset: \-?\d+
+#?    CFA fixed RA offset: \-?\d+
+    Num FDEs: 1
+    Num FREs: 3
+
+  Function Index :
+    func idx \[0\]: pc = 0x0, size = 264 bytes
+    STARTPC + CFA + FP + RA +
+#...
+    0+0004 +sp\+16 +u +[uf] +
+    0+0104 +sp\+32 +u +[uf] +
+
+#pass
diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe-common-pr33810.s b/gas/testsuite/gas/cfi-sframe/cfi-sframe-common-pr33810.s
new file mode 100644
index 00000000000..0cbbd991ca3
--- /dev/null
+++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe-common-pr33810.s
@@ -0,0 +1,7 @@
+	.cfi_startproc
+	.long 0
+	.cfi_def_cfa_offset 16
+	.ds.b 0x100
+	.cfi_def_cfa_offset 32
+	.long 0
+	.cfi_endproc
diff --git a/gas/testsuite/gas/cfi-sframe/cfi-sframe.exp b/gas/testsuite/gas/cfi-sframe/cfi-sframe.exp
index 2e0942657ae..a73e5c84033 100644
--- a/gas/testsuite/gas/cfi-sframe/cfi-sframe.exp
+++ b/gas/testsuite/gas/cfi-sframe/cfi-sframe.exp
@@ -53,6 +53,8 @@ if  { ([istarget "x86_64-*-*"] || [istarget "aarch64*-*-*"]
 
     run_dump_test "common-empty-2"
     run_dump_test "common-empty-3"
+
+    run_dump_test "cfi-sframe-common-pr33810"
 }
 
 # x86-64 specific tests
diff --git a/libsframe/sframe.c b/libsframe/sframe.c
index 52788d8ac15..3f76629665c 100644
--- a/libsframe/sframe.c
+++ b/libsframe/sframe.c
@@ -647,15 +647,14 @@ sframe_decode_fde_idx_v3 (const char *buf, size_t buf_size,
 
 static int
 sframe_decode_fde_attr_v3 (const char *buf, size_t buf_size,
-			   uint16_t *num_fres)
+			   uint16_t *num_fres, uint32_t *fre_type)
 {
   if (buf_size < sizeof (sframe_func_desc_attr_v3))
     return SFRAME_ERR;
 
-  /* sfda_func_num_fres is the first member of sframe_func_desc_attr_v3.  */
-  const struct { uint16_t x; } ATTRIBUTE_PACKED *p = (void *)buf;
-  *num_fres = p->x;
-
+  const sframe_func_desc_attr_v3 *fdap = (sframe_func_desc_attr_v3 *) buf;
+  *num_fres = fdap->sfda_func_num_fres;
+  *fre_type = SFRAME_V3_FDE_FRE_TYPE (fdap->sfda_func_info);
   return 0;
 }
 static int
@@ -855,7 +854,7 @@ flip_sframe_fdes_with_fres_v3 (char *frame_buf, size_t buf_size,
       /* Handle FDE attr (only in V3).  */
       fp = fres + fre_offset;
       if (to_foreign && sframe_decode_fde_attr_v3 (fp, buf_end - fp,
-						   &num_fres))
+						   &num_fres, &fre_type))
 	goto bad;
 
       if (flip_fde_attr_v3 (fp, buf_end - fp))
@@ -864,7 +863,7 @@ flip_sframe_fdes_with_fres_v3 (char *frame_buf, size_t buf_size,
       fre_bytes_flipped += sizeof (sframe_func_desc_attr_v3);
 
       if (!to_foreign && sframe_decode_fde_attr_v3 (fp, buf_end - fp,
-						    &num_fres))
+						    &num_fres, &fre_type))
 	goto bad;
 
       /* Handle FREs.  */