include: sframe: doc: define new flag SFRAME_F_FDE_FUNC_START_ADDR_PCREL

Add a new flag SFRAME_F_FDE_FUNC_START_ADDR_PCREL to SFrame stack trace
format.  If set, this flag indicates that the function start address
field (sfde_func_start_address) is the offset to the function start
address from the SFrame FDE function start address field itself.

Such an encoding is friendlier to the exisitng PC-REL relocations
available in the ABIs supported in SFrame: AMD64 (R_X86_64_PC32) and
AArch64 (R_AARCH64_PREL32).  In subsequent patches, we will make the
implementation in gas and ld to both:
  - emit the values in the same (above-mentioned) encoding uniformly.
  - set the flag SFRAME_F_FDE_FUNC_START_ADDR_PCREL in the SFrame header
    for consumers to be able to distinguish.

Define SFRAME_F_ALL_FLAGS in sframe-api.h to help keep the
implementation less error-prone by keeping a set of all defined flags at
a central place.  Adjust the check in sframe_header_sanity_check_p () to
use the SFRAME_F_ALL_FLAGS instead.

Add documentation for SFRAME_F_FDE_FUNC_START_ADDR_PCREL.  Update the
documentation about the encoding of the sfde_func_start_address field.

Also, update the section "Changes from Version 1 to Version 2" to
include the specification of the new flag
SFRAME_F_FDE_FUNC_START_ADDR_PCREL as an errata release to the SFrame
Version 2 specification.

include/
        * sframe-api.h (SFRAME_F_ALL_FLAGS): New definition.
        * sframe.h (SFRAME_F_FDE_FUNC_START_ADDR_PCREL): Likewise.
libsframe/
	* sframe-dump.c (dump_sframe_header_flags): Update to include
	the new flag.
	* sframe.c (sframe_header_sanity_check_p): Use uint8_t.
libsframe/doc/
	* sframe-spec.texi: Add details about the new flag.  Also update
	the defails about the sfde_func_start_address encoding.

---
[Changes in V4]
 - Define new SFRAME_F_ALL_FLAGS in sframe-api.h.  Use it in
   sframe_header_sanity_check_p ().  Mention SFRAME_F_ALL_FLAGS in the
   commit log.
 - Add one liner in the SFrame spec "Bits corresponding to the currently
   undefined flags must be set to zero."
[End of changes in V4]

[No changes in V3]

[Changes in V2]
  - Switch back to the old style of flag values.
  - Merge three patches from V1 into a single patch
    include: libsframe: add APIs for offsetof FDE func start addr field
    doc: sframe: add documentation for SFRAME_F_FDE_FUNC_START_ADDR_PCREL
    doc: sframe: update documentation for sfde_func_start_address
[End of changes in V2]

0 files changed, 0 insertions, 0 deletions