[PATCH v5 1/9] riscv: ptrace: return ENODATA for inactive vector extension

[Sergey Matyukevich]

From: Ilya Mamay <mmamayka01 at gmail.com>

Currently, ptrace returns EINVAL when the vector extension is supported
but not yet activated for the traced process. This error code is not
always appropriate since the ptrace arguments may be valid.

Debug tools like gdbserver expect ENODATA when the requested register
set is not active, e.g. see [1]. This expectation seems to be more
appropriate, so modify the vector ptrace implementation to return:
- EINVAL when V extension is not supported
- ENODATA when V extension is supported but not active

[1] https://github.com/bminor/binutils-gdb/blob/637f25e88675fa47e47f9cc5e2cf37384836b8a2/gdbserver/linux-low.cc#L5020

Signed-off-by: Ilya Mamay <mmamayka01 at gmail.com>
Signed-off-by: Sergey Matyukevich <geomatsi at gmail.com>
---
 arch/riscv/kernel/ptrace.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c
index e6272d74572f..9d203fb84f5e 100644
--- a/arch/riscv/kernel/ptrace.c
+++ b/arch/riscv/kernel/ptrace.c
@@ -95,9 +95,12 @@ static int riscv_vr_get(struct task_struct *target,
 	struct __riscv_v_ext_state *vstate = &target->thread.vstate;
 	struct __riscv_v_regset_state ptrace_vstate;
 
-	if (!riscv_v_vstate_query(task_pt_regs(target)))
+	if (!(has_vector() || has_xtheadvector()))
 		return -EINVAL;
 
+	if (!riscv_v_vstate_query(task_pt_regs(target)))
+		return -ENODATA;
+
 	/*
 	 * Ensure the vector registers have been saved to the memory before
 	 * copying them to membuf.
@@ -130,9 +133,12 @@ static int riscv_vr_set(struct task_struct *target,
 	struct __riscv_v_ext_state *vstate = &target->thread.vstate;
 	struct __riscv_v_regset_state ptrace_vstate;
 
-	if (!riscv_v_vstate_query(task_pt_regs(target)))
+	if (!(has_vector() || has_xtheadvector()))
 		return -EINVAL;
 
+	if (!riscv_v_vstate_query(task_pt_regs(target)))
+		return -ENODATA;
+
 	/* Copy rest of the vstate except datap */
 	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &ptrace_vstate, 0,
 				 sizeof(struct __riscv_v_regset_state));
-- 
2.52.0