1 files changed, 313 insertions, 0 deletions
diff --git a/arch/riscv/kernel/vector.c b/arch/riscv/kernel/vector.c
new file mode 100644
index 000000000000..6727d1d3b8f2
--- /dev/null
+++ b/arch/riscv/kernel/vector.c
@@ -0,0 +1,313 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2023 SiFive
+ * Author: Andy Chiu <andy.chiu@sifive.com>
+ */
+#include <linux/export.h>
+#include <linux/sched/signal.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/uaccess.h>
+#include <linux/prctl.h>
+
+#include <asm/thread_info.h>
+#include <asm/processor.h>
+#include <asm/insn.h>
+#include <asm/vector.h>
+#include <asm/csr.h>
+#include <asm/elf.h>
+#include <asm/ptrace.h>
+#include <asm/bug.h>
+
+static bool riscv_v_implicit_uacc = IS_ENABLED(CONFIG_RISCV_ISA_V_DEFAULT_ENABLE);
+static struct kmem_cache *riscv_v_user_cachep;
+#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE
+static struct kmem_cache *riscv_v_kernel_cachep;
+#endif
+
+unsigned long riscv_v_vsize __read_mostly;
+EXPORT_SYMBOL_GPL(riscv_v_vsize);
+
+int riscv_v_setup_vsize(void)
+{
+	unsigned long this_vsize;
+
+	/* There are 32 vector registers with vlenb length. */
+	riscv_v_enable();
+	this_vsize = csr_read(CSR_VLENB) * 32;
+	riscv_v_disable();
+
+	if (!riscv_v_vsize) {
+		riscv_v_vsize = this_vsize;
+		return 0;
+	}
+
+	if (riscv_v_vsize != this_vsize) {
+		WARN(1, "RISCV_ISA_V only supports one vlenb on SMP systems");
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+void __init riscv_v_setup_ctx_cache(void)
+{
+	if (!has_vector())
+		return;
+
+	riscv_v_user_cachep = kmem_cache_create_usercopy("riscv_vector_ctx",
+							 riscv_v_vsize, 16, SLAB_PANIC,
+							 0, riscv_v_vsize, NULL);
+#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE
+	riscv_v_kernel_cachep = kmem_cache_create("riscv_vector_kctx",
+						  riscv_v_vsize, 16,
+						  SLAB_PANIC, NULL);
+#endif
+}
+
+static bool insn_is_vector(u32 insn_buf)
+{
+	u32 opcode = insn_buf & __INSN_OPCODE_MASK;
+	u32 width, csr;
+
+	/*
+	 * All V-related instructions, including CSR operations are 4-Byte. So,
+	 * do not handle if the instruction length is not 4-Byte.
+	 */
+	if (unlikely(GET_INSN_LENGTH(insn_buf) != 4))
+		return false;
+
+	switch (opcode) {
+	case RVV_OPCODE_VECTOR:
+		return true;
+	case RVV_OPCODE_VL:
+	case RVV_OPCODE_VS:
+		width = RVV_EXRACT_VL_VS_WIDTH(insn_buf);
+		if (width == RVV_VL_VS_WIDTH_8 || width == RVV_VL_VS_WIDTH_16 ||
+		    width == RVV_VL_VS_WIDTH_32 || width == RVV_VL_VS_WIDTH_64)
+			return true;
+
+		break;
+	case RVG_OPCODE_SYSTEM:
+		csr = RVG_EXTRACT_SYSTEM_CSR(insn_buf);
+		if ((csr >= CSR_VSTART && csr <= CSR_VCSR) ||
+		    (csr >= CSR_VL && csr <= CSR_VLENB))
+			return true;
+	}
+
+	return false;
+}
+
+static int riscv_v_thread_zalloc(struct kmem_cache *cache,
+				 struct __riscv_v_ext_state *ctx)
+{
+	void *datap;
+
+	datap = kmem_cache_zalloc(cache, GFP_KERNEL);
+	if (!datap)
+		return -ENOMEM;
+
+	ctx->datap = datap;
+	memset(ctx, 0, offsetof(struct __riscv_v_ext_state, datap));
+	return 0;
+}
+
+void riscv_v_thread_alloc(struct task_struct *tsk)
+{
+#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE
+	riscv_v_thread_zalloc(riscv_v_kernel_cachep, &tsk->thread.kernel_vstate);
+#endif
+}
+
+void riscv_v_thread_free(struct task_struct *tsk)
+{
+	if (tsk->thread.vstate.datap)
+		kmem_cache_free(riscv_v_user_cachep, tsk->thread.vstate.datap);
+#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE
+	if (tsk->thread.kernel_vstate.datap)
+		kmem_cache_free(riscv_v_kernel_cachep, tsk->thread.kernel_vstate.datap);
+#endif
+}
+
+#define VSTATE_CTRL_GET_CUR(x) ((x) & PR_RISCV_V_VSTATE_CTRL_CUR_MASK)
+#define VSTATE_CTRL_GET_NEXT(x) (((x) & PR_RISCV_V_VSTATE_CTRL_NEXT_MASK) >> 2)
+#define VSTATE_CTRL_MAKE_NEXT(x) (((x) << 2) & PR_RISCV_V_VSTATE_CTRL_NEXT_MASK)
+#define VSTATE_CTRL_GET_INHERIT(x) (!!((x) & PR_RISCV_V_VSTATE_CTRL_INHERIT))
+static inline int riscv_v_ctrl_get_cur(struct task_struct *tsk)
+{
+	return VSTATE_CTRL_GET_CUR(tsk->thread.vstate_ctrl);
+}
+
+static inline int riscv_v_ctrl_get_next(struct task_struct *tsk)
+{
+	return VSTATE_CTRL_GET_NEXT(tsk->thread.vstate_ctrl);
+}
+
+static inline bool riscv_v_ctrl_test_inherit(struct task_struct *tsk)
+{
+	return VSTATE_CTRL_GET_INHERIT(tsk->thread.vstate_ctrl);
+}
+
+static inline void riscv_v_ctrl_set(struct task_struct *tsk, int cur, int nxt,
+				    bool inherit)
+{
+	unsigned long ctrl;
+
+	ctrl = cur & PR_RISCV_V_VSTATE_CTRL_CUR_MASK;
+	ctrl |= VSTATE_CTRL_MAKE_NEXT(nxt);
+	if (inherit)
+		ctrl |= PR_RISCV_V_VSTATE_CTRL_INHERIT;
+	tsk->thread.vstate_ctrl &= ~PR_RISCV_V_VSTATE_CTRL_MASK;
+	tsk->thread.vstate_ctrl |= ctrl;
+}
+
+bool riscv_v_vstate_ctrl_user_allowed(void)
+{
+	return riscv_v_ctrl_get_cur(current) == PR_RISCV_V_VSTATE_CTRL_ON;
+}
+EXPORT_SYMBOL_GPL(riscv_v_vstate_ctrl_user_allowed);
+
+bool riscv_v_first_use_handler(struct pt_regs *regs)
+{
+	u32 __user *epc = (u32 __user *)regs->epc;
+	u32 insn = (u32)regs->badaddr;
+
+	/* Do not handle if V is not supported, or disabled */
+	if (!(ELF_HWCAP & COMPAT_HWCAP_ISA_V))
+		return false;
+
+	/* If V has been enabled then it is not the first-use trap */
+	if (riscv_v_vstate_query(regs))
+		return false;
+
+	/* Get the instruction */
+	if (!insn) {
+		if (__get_user(insn, epc))
+			return false;
+	}
+
+	/* Filter out non-V instructions */
+	if (!insn_is_vector(insn))
+		return false;
+
+	/* Sanity check. datap should be null by the time of the first-use trap */
+	WARN_ON(current->thread.vstate.datap);
+
+	/*
+	 * Now we sure that this is a V instruction. And it executes in the
+	 * context where VS has been off. So, try to allocate the user's V
+	 * context and resume execution.
+	 */
+	if (riscv_v_thread_zalloc(riscv_v_user_cachep, &current->thread.vstate)) {
+		force_sig(SIGBUS);
+		return true;
+	}
+	riscv_v_vstate_on(regs);
+	riscv_v_vstate_set_restore(current, regs);
+	return true;
+}
+
+void riscv_v_vstate_ctrl_init(struct task_struct *tsk)
+{
+	bool inherit;
+	int cur, next;
+
+	if (!has_vector())
+		return;
+
+	next = riscv_v_ctrl_get_next(tsk);
+	if (!next) {
+		if (READ_ONCE(riscv_v_implicit_uacc))
+			cur = PR_RISCV_V_VSTATE_CTRL_ON;
+		else
+			cur = PR_RISCV_V_VSTATE_CTRL_OFF;
+	} else {
+		cur = next;
+	}
+	/* Clear next mask if inherit-bit is not set */
+	inherit = riscv_v_ctrl_test_inherit(tsk);
+	if (!inherit)
+		next = PR_RISCV_V_VSTATE_CTRL_DEFAULT;
+
+	riscv_v_ctrl_set(tsk, cur, next, inherit);
+}
+
+long riscv_v_vstate_ctrl_get_current(void)
+{
+	if (!has_vector())
+		return -EINVAL;
+
+	return current->thread.vstate_ctrl & PR_RISCV_V_VSTATE_CTRL_MASK;
+}
+
+long riscv_v_vstate_ctrl_set_current(unsigned long arg)
+{
+	bool inherit;
+	int cur, next;
+
+	if (!has_vector())
+		return -EINVAL;
+
+	if (arg & ~PR_RISCV_V_VSTATE_CTRL_MASK)
+		return -EINVAL;
+
+	cur = VSTATE_CTRL_GET_CUR(arg);
+	switch (cur) {
+	case PR_RISCV_V_VSTATE_CTRL_OFF:
+		/* Do not allow user to turn off V if current is not off */
+		if (riscv_v_ctrl_get_cur(current) != PR_RISCV_V_VSTATE_CTRL_OFF)
+			return -EPERM;
+
+		break;
+	case PR_RISCV_V_VSTATE_CTRL_ON:
+		break;
+	case PR_RISCV_V_VSTATE_CTRL_DEFAULT:
+		cur = riscv_v_ctrl_get_cur(current);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	next = VSTATE_CTRL_GET_NEXT(arg);
+	inherit = VSTATE_CTRL_GET_INHERIT(arg);
+	switch (next) {
+	case PR_RISCV_V_VSTATE_CTRL_DEFAULT:
+	case PR_RISCV_V_VSTATE_CTRL_OFF:
+	case PR_RISCV_V_VSTATE_CTRL_ON:
+		riscv_v_ctrl_set(current, cur, next, inherit);
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+#ifdef CONFIG_SYSCTL
+
+static struct ctl_table riscv_v_default_vstate_table[] = {
+	{
+		.procname	= "riscv_v_default_allow",
+		.data		= &riscv_v_implicit_uacc,
+		.maxlen		= sizeof(riscv_v_implicit_uacc),
+		.mode		= 0644,
+		.proc_handler	= proc_dobool,
+	},
+};
+
+static int __init riscv_v_sysctl_init(void)
+{
+	if (has_vector())
+		if (!register_sysctl("abi", riscv_v_default_vstate_table))
+			return -EINVAL;
+	return 0;
+}
+
+#else /* ! CONFIG_SYSCTL */
+static int __init riscv_v_sysctl_init(void) { return 0; }
+#endif /* ! CONFIG_SYSCTL */
+
+static int riscv_v_init(void)
+{
+	return riscv_v_sysctl_init();
+}
+core_initcall(riscv_v_init);