[PATCH] libsframe: use proper FRE type when flipping SFrame V3 FREs

[Jens Remus]

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>
---
 .../cfi-sframe/cfi-sframe-common-pr33810.d    | 23 +++++++++++++++++++
 .../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(-)
 create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-pr33810.d
 create mode 100644 gas/testsuite/gas/cfi-sframe/cfi-sframe-common-pr33810.s

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 000000000000..ae8b76a6effb
--- /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 000000000000..0cbbd991ca38
--- /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 2e0942657ae9..a73e5c84033e 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 52788d8ac152..3f76629665cb 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.  */
-- 
2.51.0