RISC-V: Add ptrace support for vectors

This patch add back the ptrace support with the following fix:
 - Define NT_RISCV_CSR and re-number NT_RISCV_VECTOR to prevent
   conflicting with gdb's NT_RISCV_CSR.
 - Use struct __riscv_v_regset_state to handle ptrace requests

Since gdb does not directly include the note description header in
Linux and has already defined NT_RISCV_CSR as 0x900, we decide to
sync with gdb and renumber NT_RISCV_VECTOR to solve and prevent future
conflicts.

Fixes: 0c59922c769a ("riscv: Add ptrace vector support")
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Link: https://lore.kernel.org/r/20230825050248.32681-1-andy.chiu@sifive.com
[Palmer: Drop the unused "size" variable in riscv_vr_set().]
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

1 files changed, 9 insertions, 4 deletions

diff --git a/arch/riscv/include/uapi/asm/ptrace.h b/arch/riscv/include/uapi/asm/ptrace.h
index 283800130614..575e95bb1bc3 100644
--- a/arch/riscv/include/uapi/asm/ptrace.h
+++ b/arch/riscv/include/uapi/asm/ptrace.h
@@ -103,13 +103,18 @@ struct __riscv_v_ext_state {
 	 * In signal handler, datap will be set a correct user stack offset
 	 * and vector registers will be copied to the address of datap
 	 * pointer.
-	 *
-	 * In ptrace syscall, datap will be set to zero and the vector
-	 * registers will be copied to the address right after this
-	 * structure.
 	 */
 };
 
+struct __riscv_v_regset_state {
+	unsigned long vstart;
+	unsigned long vl;
+	unsigned long vtype;
+	unsigned long vcsr;
+	unsigned long vlenb;
+	char vreg[];
+};
+
 /*
  * According to spec: The number of bits in a single vector register,
  * VLEN >= ELEN, which must be a power of 2, and must be no greater than