From: Srinath Parvathaneni <[email protected]>
Changes v2 -> v3:
Patch 1:
* Address review comments.
* After discussion, retain the _EL0 suffix for the POE register.
* Merge the POR_EL0 custom printing support from v2 Patch 2.
* Update the XML description to use the POR_EL0_FLAGS type for
custom register printing.
Patch 2:
* Corresponds to v2 Patch 3.
* No functional changes.
* Approved by Thiago Jung Bauermann.
Patch 3:
* Corresponds to v2 Patch 4.
* No functional changes.
* Approved by Thiago Jung Bauermann.
Patch 4:
* The BFD/readelf changes from v2 Patch 5 have been posted separately
to binutils-gdb and have since been approved and committed.
* Corresponds to v2 Patch 6.
* Address review comments on the GDB core file support.
Patch 5:
* Corresponds to v2 Patch 7.
* Address review comments.
* Update the tests to reflect the POR_EL0 custom string shown by
`info registers por_el0` and `print $por_el0`.
* Fix aarch64-poe-core.exp test issues.
* Rebased onto current upstream master, including:
* Matthieu Longo's "gdb: align siginfo_t with the Linux kernel definition".
* My "gdb: Fix assignment to TYPE_CODE_FLAGS registers" patch.
----------------
Changes v1 -> v2:
* Rebased the SIGSEGV diagnostic support on Matthieu Longo's generic
"siginfo_t" changes, using the new "_._addr_pkey.si_pkey" layout
instead of introducing a target-specific "siginfo_t" extension.
* Split the original series into smaller, subsystem-specific patches:
* GDB register support
* POR_EL0 pretty printing
* SIGSEGV diagnostics
* gdbserver support
* BFD/readelf core file support
* GDB core file support
* Testsuite
* Separated BFD/readelf and GDB core file support into independent
patches.
* Retained FEAT_S1POE expansion as "Permission Overlay Extension" after internal discussion.
* Removed the POR_EL0 permission decoding string (e.g. `por_el0[pkey=<value>] = rwx`) from
SIGSEGV diagnostics, as displaying permissions without also showing base and effective
permissions can be misleading to users.
* Rebased the series onto current upstream master + Matthieu's patch
"gdb: align siginfo_t with the Linux kernel definition"
----------------
Hi,
This series adds support for the AArch64 Permission Overlay Extension
(FEAT_S1POE) in GDB and gdbserver.
The series introduces support for the POR_EL0 register, allowing GDB
to read and write it using the Linux NT_ARM_POE regset. It also improves
SIGSEGV diagnostics for Permission Overlay violations, extends gdbserver
to transfer POR_EL0 during remote debugging, restores POR_EL0 from core
files, and adds testsuite coverage.
The BFD/readelf support for the NT_ARM_POE core note has already been
posted and approved separately.
commit d15490528409305f97004a2860fdb04543862774
Author: Srinath Parvathaneni <[email protected]>
Date: Thu Jul 2 13:57:25 2026 +0000
bfd/readelf: Add core file support for FEAT_S1POE
The series consists of the following patches:
[1/5] gdb/aarch64: Add POR_EL0 register support
Add support for reading and writing the POR_EL0 register using the Linux
NT_ARM_POE regset.
[2/5] gdb: Improve SIGSEGV diagnostics for POE faults
Report the faulting address together with the associated protection key
for Permission Overlay violations.
[3/5] gdbserver/aarch64: Add POR_EL0 register support
Transfer the POR register through the Linux NT_ARM_POE regset during
remote debugging.
[4/5] gdb/aarch64: Add core file support for FEAT_S1POE
Restore the POR_EL0 register from Linux core files and signal frames.
[5/5] gdb/testsuite: Add FEAT_S1POE testcases
Add tests covering POR_EL0 register access, SIGSEGV diagnostics,
fix-and-continue support, and core file support.
The series has been tested natively and using gdbserver with remote GDB
on an FVP built using shrinkwrap with a Linux kernel configured with
CONFIG_ARM64_POE=y and a glibc version providing userspace POE support.
Regression tested on aarch64-none-linux-gnu with no regressions.
Ok for GDB master?
----------
>> This series adds support for the AArch64 Permission Overlay Extension
>> (FEAT_S1POE) in GDB, gdbserver, BFD and the testsuite.
>
> Hi Srinath!
>
> I don't know much about the arm architecture or this extension in
> specific, but it seems that it at least adds new registers so this seems
> like a valid question: Do these impact recording of ARM instructions
> with the record-full subsystem at all?
>
> It would be nice to have a gdb.reverse test that exercises some (ideally
> all) new instructions if there are any, and some other instructions that
> manipulate those new registers, if needed.
>
> This isn't required to get this series merged, of course, but it would
> be very nice to have it.
Hi Guinevere,
As far as I understand, FEAT_S1POE doesn't introduce any new AArch64
instructions in userspace, it only exposes the POR_EL0 register, which
is accessed through the Linux Protection-key APIs. The register itself
is managed by the kernel rather than being modified by normal AArch64
instructions. Because of that, I don't think this support has any impact
on the record-full subsystem.
Thanks for the suggestion about adding gdb.reverse tests. I'll keep that
in mind for other feature support.
Regards,
Srinath
Srinath Parvathaneni (5):
gdb/aarch64: Add POR_EL0 register support for FEAT_S1POE
gdb: Improve SIGSEGV diagnostics for POE faults
gdbserver/aarch64: Add POR_EL0 register support
gdb/aarch64: Add core file support for FEAT_S1POE
gdb/testsuite: Add FEAT_S1POE testcases
gdb/Makefile.in | 2 +
gdb/aarch64-linux-nat.c | 64 +++++++++++
gdb/aarch64-linux-tdep.c | 71 +++++++++++-
gdb/aarch64-tdep.c | 23 ++++
gdb/aarch64-tdep.h | 10 ++
gdb/arch/aarch64-poe-linux.h | 29 +++++
gdb/arch/aarch64.c | 4 +
gdb/arch/aarch64.h | 8 +-
gdb/features/Makefile | 1 +
gdb/features/aarch64-poe.c | 68 ++++++++++++
gdb/features/aarch64-poe.xml | 47 ++++++++
gdb/nat/aarch64-poe-linux.h | 29 +++++
gdb/testsuite/gdb.arch/aarch64-poe-core.exp | 101 ++++++++++++++++++
gdb/testsuite/gdb.arch/aarch64-poe-sigsegv. | 0
gdb/testsuite/gdb.arch/aarch64-poe-sigsegv.c | 52 +++++++++
.../gdb.arch/aarch64-poe-sigsegv.exp | 58 ++++++++++
gdb/testsuite/gdb.arch/aarch64-poe.c | 29 +++++
gdb/testsuite/gdb.arch/aarch64-poe.exp | 46 ++++++++
gdb/testsuite/lib/gdb.exp | 55 ++++++++++
gdbserver/linux-aarch64-low.cc | 30 ++++++
20 files changed, 723 insertions(+), 4 deletions(-)
create mode 100644 gdb/arch/aarch64-poe-linux.h
create mode 100644 gdb/features/aarch64-poe.c
create mode 100644 gdb/features/aarch64-poe.xml
create mode 100644 gdb/nat/aarch64-poe-linux.h
create mode 100644 gdb/testsuite/gdb.arch/aarch64-poe-core.exp
create mode 100644 gdb/testsuite/gdb.arch/aarch64-poe-sigsegv.
create mode 100644 gdb/testsuite/gdb.arch/aarch64-poe-sigsegv.c
create mode 100644 gdb/testsuite/gdb.arch/aarch64-poe-sigsegv.exp
create mode 100644 gdb/testsuite/gdb.arch/aarch64-poe.c
create mode 100644 gdb/testsuite/gdb.arch/aarch64-poe.exp
--
2.43.0
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