riscv: ptrace: reject CFI regset access when extensions are absent

riscv_cfi_get() and riscv_cfi_set() do not check whether the Zicfilp
or Zicfiss extensions are present. On systems without them,
PTRACE_GETREGSET on REGSET_CFI still succeeds and returns a zeroed
user_cfi_state, misleading debuggers into believing the register set
is available, and PTRACE_SETREGSET silently accepts writes that have
no effect (e.g. clearing SR_ELP).

Reject the access with -EINVAL when neither branch landing pads nor
shadow stack is available to userspace, using the same availability
helpers as the prctl path.

Fixes: 2af7c9cf021c ("riscv/ptrace: expose riscv CFI status and state via ptrace and in core files")
Signed-off-by: Chen Pei <cp0613@linux.alibaba.com>
Link: https://patch.msgid.link/20260820063233.2567-1-cp0613@linux.alibaba.com
Cc: stable@vger.kernel.org
Signed-off-by: Paul Walmsley <pjw@kernel.org>

0 files changed, 0 insertions, 0 deletions