[RFC PATCH v4 12/13] riscv: Add sigcontext save/restore for vector

[Greentime Hu]

From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>

This patch adds sigcontext save/restore for vector. The vector registers
will be saved in datap pointer. The datap pointer will be allocaed
dynamically when the task needs in kernel space. The datap pointer will
be set right after the __riscv_v_state data structure to save all the
vector registers in the signal handler stack.

[greentime.hu@xxxxxxxxxx: add support for dynamic vlen]
Signed-off-by: Greentime Hu <greentime.hu@xxxxxxxxxx>
Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx>
---
 arch/riscv/include/uapi/asm/sigcontext.h |  2 +
 arch/riscv/kernel/signal.c               | 92 +++++++++++++++++++++++-
 2 files changed, 91 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/include/uapi/asm/sigcontext.h b/arch/riscv/include/uapi/asm/sigcontext.h
index 84f2dfcfdbce..4217f3f1c8ba 100644
--- a/arch/riscv/include/uapi/asm/sigcontext.h
+++ b/arch/riscv/include/uapi/asm/sigcontext.h
@@ -8,6 +8,7 @@
 
 #include <asm/ptrace.h>
 
+#define RVV_MAGIC	0x53465457
 /*
  * Signal context structure
  *
@@ -17,6 +18,7 @@
 struct sigcontext {
 	struct user_regs_struct sc_regs;
 	union __riscv_fp_state sc_fpregs;
+	struct __riscv_v_state sc_vregs;
 };
 
 #endif /* _UAPI_ASM_RISCV_SIGCONTEXT_H */
diff --git a/arch/riscv/kernel/signal.c b/arch/riscv/kernel/signal.c
index 17ba190e84a5..9ada6f74bb95 100644
--- a/arch/riscv/kernel/signal.c
+++ b/arch/riscv/kernel/signal.c
@@ -83,6 +83,80 @@ static long save_fp_state(struct pt_regs *regs,
 #define restore_fp_state(task, regs) (0)
 #endif
 
+#ifdef CONFIG_VECTOR
+static long restore_v_state(struct pt_regs *regs, struct sigcontext *sc)
+{
+	long err;
+	struct __riscv_v_state __user *state = &sc->sc_vregs;
+	void *datap;
+	__u32 magic;
+
+	/* Get magic number and check it. */
+	err = __get_user(magic, &state->magic);
+	if (unlikely(err))
+		return err;
+
+	if (magic != RVV_MAGIC)
+		return -EINVAL;
+
+	/* Copy everything of __riscv_v_state except datap. */
+	err = __copy_from_user(&current->thread.vstate, state,
+			       RISCV_V_STATE_DATAP);
+	if (unlikely(err))
+		return err;
+
+	/* Copy the pointer datap itself. */
+	err = __get_user(datap, &state->datap);
+	if (unlikely(err))
+		return err;
+
+
+	/* Copy the whole vector content from user space datap. */
+	err = __copy_from_user(current->thread.vstate.datap, datap,
+			       current->thread.vstate.size);
+	if (unlikely(err))
+		return err;
+
+	vstate_restore(current, regs);
+
+	return err;
+}
+
+static long save_v_state(struct pt_regs *regs, struct sigcontext *sc)
+{
+	long err;
+	struct __riscv_v_state __user *state = &sc->sc_vregs;
+	/* Set the datap right after the sigcntext structure. */
+	void *datap = sc + 1;
+
+	vstate_save(current, regs);
+	/* Copy everything of vstate but datap. */
+	err = __copy_to_user(state, &current->thread.vstate,
+			     RISCV_V_STATE_DATAP);
+	if (unlikely(err))
+		return err;
+
+	/* Copy the magic number. */
+	err = __put_user(RVV_MAGIC, &state->magic);
+	if (unlikely(err))
+		return err;
+
+	/* Copy the pointer datap itself. */
+	err = __put_user(datap, &state->datap);
+	if (unlikely(err))
+		return err;
+
+	/* Copy the whole vector content to user space datap. */
+	err = __copy_to_user(datap, current->thread.vstate.datap,
+			     current->thread.vstate.size);
+
+	return err;
+}
+#else
+#define save_v_state(task, regs) (0)
+#define restore_v_state(task, regs) (0)
+#endif
+
 static long restore_sigcontext(struct pt_regs *regs,
 	struct sigcontext __user *sc)
 {
@@ -92,6 +166,9 @@ static long restore_sigcontext(struct pt_regs *regs,
 	/* Restore the floating-point state. */
 	if (has_fpu)
 		err |= restore_fp_state(regs, &sc->sc_fpregs);
+	/* Restore the vector state. */
+	if (has_vector)
+		err |= restore_v_state(regs, sc);
 	return err;
 }
 
@@ -101,13 +178,16 @@ SYSCALL_DEFINE0(rt_sigreturn)
 	struct rt_sigframe __user *frame;
 	struct task_struct *task;
 	sigset_t set;
+	size_t frame_size = sizeof(*frame);
 
 	/* Always make any pending restarted system calls return -EINTR */
 	current->restart_block.fn = do_no_restart_syscall;
 
 	frame = (struct rt_sigframe __user *)regs->sp;
 
-	if (!access_ok(frame, sizeof(*frame)))
+	if (has_vector)
+		frame_size += current->thread.vstate.size;
+	if (!access_ok(frame, frame_size))
 		goto badframe;
 
 	if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
@@ -145,6 +225,9 @@ static long setup_sigcontext(struct rt_sigframe __user *frame,
 	/* Save the floating-point state. */
 	if (has_fpu)
 		err |= save_fp_state(regs, &sc->sc_fpregs);
+	/* Save the vector state. */
+	if (has_vector)
+		err |= save_v_state(regs, sc);
 	return err;
 }
 
@@ -176,9 +259,12 @@ static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 {
 	struct rt_sigframe __user *frame;
 	long err = 0;
+	size_t frame_size = sizeof(*frame);
 
-	frame = get_sigframe(ksig, regs, sizeof(*frame));
-	if (!access_ok(frame, sizeof(*frame)))
+	if (has_vector)
+		frame_size += current->thread.vstate.size;
+	frame = get_sigframe(ksig, regs, frame_size);
+	if (!access_ok(frame, frame_size))
 		return -EFAULT;
 
 	err |= copy_siginfo_to_user(&frame->info, &ksig->info);
-- 
2.26.2