linux-kernel - [PATCH v2 2/6] riscv: ptrace: return ENODATA for inactive vector extension

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Message-ID: <20251007115840.2320557-3-geomatsi@gmail.com>
Date: Tue,  7 Oct 2025 14:58:18 +0300
From: Sergey Matyukevich <geomatsi@...il.com>
To: linux-riscv@...ts.infradead.org,
	linux-kselftest@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Paul Walmsley <pjw@...nel.org>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>,
	Oleg Nesterov <oleg@...hat.com>,
	Shuah Khan <shuah@...nel.org>,
	Jisheng Zhang <jszhang@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Thomas Huth <thuth@...hat.com>,
	Charlie Jenkins <charlie@...osinc.com>,
	Andy Chiu <andybnac@...il.com>,
	Han Gao <rabenda.cn@...il.com>,
	Samuel Holland <samuel.holland@...ive.com>,
	Nam Cao <namcao@...utronix.de>,
	Joel Granados <joel.granados@...nel.org>,
	Clément Léger <cleger@...osinc.com>,
	Conor Dooley <conor.dooley@...rochip.com>,
	Sergey Matyukevich <geomatsi@...il.com>,
	Ilya Mamay <mmamayka01@...il.com>
Subject: [PATCH v2 2/6] riscv: ptrace: return ENODATA for inactive vector extension

From: Ilya Mamay <mmamayka01@...il.com>

Currently, ptrace returns EINVAL when the vector extension is supported
but not yet activated for the traced process. This error code is
inappropriate since all the ptrace arguments are 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@...il.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 8e86305831ea..906cf1197edc 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())
 		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())
 		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));
-- 
2.51.0