Currently uprobes and the Arm Guarded Control Stack (GCS) feature are
exclusive of each other. This restriction needs to be lifted in order
to utilize GCS for generic Linux distro images where the expectation
is that core debugging features like uprobes work.
This series adds some user accessors to read/push/pop the userspace
shadow stack. It then utilizes those functions in the uprobe paths as
needed to synchronize GCS with the changes in control flow at probe
locations.
The KCONFIG restriction is then dropped.
v4->v5: Fix ret xn handing
Renames, comment tweaks, formatting, per review comments
rebase 6.17, drop first patch
Add reviewed-by's
v3->v4: Much delayed v4 rebased to 6.16
Move existing gcs accessors to gcs.h and then add the new
ones. This fixes some of the forward reference issues,
the build break and keeps them all together.
v2->v3: Cleanup RET logic to alwaays use LR, and not update IP on aborts
Correct generic uprobe_warn bug even though we aren't using it
v1->v2:
Drop uprobe_warn() patch
Fix copy_thread_gcs() bug created by fixing task_gcs_el0_enabled()
Comments, now describe issues with reading userspace GCS pages
Rebased to 6.15
Jeremy Linton (7):
arm64: probes: Break ret out from bl/blr
arm64: uaccess: Move existing GCS accessors definitions to gcs.h
arm64: uaccess: Add additional userspace GCS accessors
arm64: probes: Add GCS support to bl/blr/ret
arm64: uprobes: Add GCS support to uretprobes
arm64: Kconfig: Remove GCS restrictions on UPROBES
uprobes: uprobe_warn should use passed task
arch/arm64/Kconfig | 1 -
arch/arm64/include/asm/gcs.h | 89 ++++++++++++++++++++++++
arch/arm64/include/asm/uaccess.h | 40 -----------
arch/arm64/kernel/probes/decode-insn.c | 7 +-
arch/arm64/kernel/probes/simulate-insn.c | 50 ++++++++++---
arch/arm64/kernel/probes/simulate-insn.h | 3 +-
arch/arm64/kernel/probes/uprobes.c | 33 +++++++++
kernel/events/uprobes.c | 2 +-
8 files changed, 171 insertions(+), 54 deletions(-)
--
2.50.1
