[v3,2/3] Detect SVE when reading aarch64 core files
Commit Message
Add a function which reads the vector length from the SVE section within an
aarch64 core file.
The SVE section in a core file contains a header followed by the registers.
Add defines to easily access the header fields within a buffer.
2018-08-10 Alan Hayward <alan.hayward@arm.com>
* aarch64-linux-tdep.c (SVE_HEADER_SIZE_LENGTH): Add define.
(SVE_HEADER_MAX_SIZE_LENGTH): Likewise.
(SVE_HEADER_VL_LENGTH): Likewise.
(SVE_HEADER_MAX_VL_LENGTH): Likewise.
(SVE_HEADER_FLAGS_LENGTH): Likewise.
(SVE_HEADER_RESERVED_LENGTH): Likewise.
(SVE_HEADER_SIZE_OFFSET): Likewise.
(SVE_HEADER_MAX_SIZE_OFFSET): Likewise.
(SVE_HEADER_VL_OFFSET): Likewise.
(SVE_HEADER_MAX_VL_OFFSET): Likewise.
(SVE_HEADER_FLAGS_OFFSET): Likewise.
(SVE_HEADER_RESERVED_OFFSET): Likewise.
(SVE_HEADER_SIZE): Likewise.
(aarch64_linux_core_read_vq): Add function.
(aarch64_linux_core_read_description): Check for SVE section.
---
gdb/aarch64-linux-tdep.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 70 insertions(+), 3 deletions(-)
Comments
Hi Alan,
LGTM with a nit/suggestion.
> + uint64_t vl = extract_unsigned_integer (header + SVE_HEADER_VL_OFFSET,
> + SVE_HEADER_VL_LENGTH, byte_order);
> + uint64_t vq = sve_vq_from_vl (vl);
> +
> + if (vq > AARCH64_MAX_SVE_VQ || vq == 0)
> + {
> + warning (_("sve header invalid in "
> + "'.reg-aarch-sve' section in core file."));
> + return 0;
> + }
If higher vq/vl values are expected to be supported in the future (the definition
of AARCH64_MAX_SVE_VQ says "Increase if required"), it might be good to provide a
more specific error message in that case. Something that says "this value of vq/vl
(32) is not supported by this GDB" (but in user-friendly). Otherwise, a user might
think that the core file is corrupted, when actually they have an old GDB that did
not support that vector size.
It's just a suggestion, I leave that up to you. The patch is good either way.
Simon
@@ -219,6 +219,74 @@ const struct regset aarch64_linux_fpregset =
regcache_supply_regset, regcache_collect_regset
};
+/* The fields in an SVE header at the start of a SVE regset. */
+
+#define SVE_HEADER_SIZE_LENGTH 4
+#define SVE_HEADER_MAX_SIZE_LENGTH 4
+#define SVE_HEADER_VL_LENGTH 2
+#define SVE_HEADER_MAX_VL_LENGTH 2
+#define SVE_HEADER_FLAGS_LENGTH 2
+#define SVE_HEADER_RESERVED_LENGTH 2
+
+#define SVE_HEADER_SIZE_OFFSET 0
+#define SVE_HEADER_MAX_SIZE_OFFSET \
+ (SVE_HEADER_SIZE_OFFSET + SVE_HEADER_SIZE_LENGTH)
+#define SVE_HEADER_VL_OFFSET \
+ (SVE_HEADER_MAX_SIZE_OFFSET + SVE_HEADER_MAX_SIZE_LENGTH)
+#define SVE_HEADER_MAX_VL_OFFSET \
+ (SVE_HEADER_VL_OFFSET + SVE_HEADER_VL_LENGTH)
+#define SVE_HEADER_FLAGS_OFFSET \
+ (SVE_HEADER_MAX_VL_OFFSET + SVE_HEADER_MAX_VL_LENGTH)
+#define SVE_HEADER_RESERVED_OFFSET \
+ (SVE_HEADER_FLAGS_OFFSET + SVE_HEADER_FLAGS_LENGTH)
+#define SVE_HEADER_SIZE \
+ (SVE_HEADER_RESERVED_OFFSET + SVE_HEADER_RESERVED_LENGTH)
+
+/* Get VQ value from SVE section in the core dump. */
+
+static uint64_t
+aarch64_linux_core_read_vq (struct gdbarch *gdbarch, bfd *abfd)
+{
+ gdb_byte header[SVE_HEADER_SIZE];
+ enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
+ asection *sve_section = bfd_get_section_by_name (abfd, ".reg-aarch-sve");
+
+ if (sve_section == nullptr)
+ {
+ /* No SVE state. */
+ return 0;
+ }
+
+ size_t size = bfd_section_size (abfd, sve_section);
+
+ /* Check extended state size. */
+ if (size < SVE_HEADER_SIZE)
+ {
+ warning (_("'.reg-aarch-sve' section in core file too small."));
+ return 0;
+ }
+
+ if (!bfd_get_section_contents (abfd, sve_section, header, 0, SVE_HEADER_SIZE))
+ {
+ warning (_("Couldn't read sve header from "
+ "'.reg-aarch-sve' section in core file."));
+ return 0;
+ }
+
+ uint64_t vl = extract_unsigned_integer (header + SVE_HEADER_VL_OFFSET,
+ SVE_HEADER_VL_LENGTH, byte_order);
+ uint64_t vq = sve_vq_from_vl (vl);
+
+ if (vq > AARCH64_MAX_SVE_VQ || vq == 0)
+ {
+ warning (_("sve header invalid in "
+ "'.reg-aarch-sve' section in core file."));
+ return 0;
+ }
+
+ return vq;
+}
+
/* Implement the "regset_from_core_section" gdbarch method. */
static void
@@ -233,8 +301,7 @@ aarch64_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
&aarch64_linux_fpregset, NULL, cb_data);
}
-/* Implement the "core_read_description" gdbarch method. SVE not yet
- supported. */
+/* Implement the "core_read_description" gdbarch method. */
static const struct target_desc *
aarch64_linux_core_read_description (struct gdbarch *gdbarch,
@@ -245,7 +312,7 @@ aarch64_linux_core_read_description (struct gdbarch *gdbarch,
if (target_auxv_search (target, AT_HWCAP, &aarch64_hwcap) != 1)
return NULL;
- return aarch64_read_description (0);
+ return aarch64_read_description (aarch64_linux_core_read_vq (gdbarch, abfd));
}
/* Implementation of `gdbarch_stap_is_single_operand', as defined in