1 files changed, 419 insertions, 0 deletions
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
new file mode 100644
index 000000000000..31a392993cb4
--- /dev/null
+++ b/arch/riscv/kernel/process.c
@@ -0,0 +1,419 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2009 Sunplus Core Technology Co., Ltd.
+ *  Chen Liqin <liqin.chen@sunplusct.com>
+ *  Lennox Wu <lennox.wu@sunplusct.com>
+ * Copyright (C) 2012 Regents of the University of California
+ * Copyright (C) 2017 SiFive
+ */
+
+#include <linux/bitfield.h>
+#include <linux/cpu.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/tick.h>
+#include <linux/ptrace.h>
+#include <linux/uaccess.h>
+#include <linux/personality.h>
+#include <linux/entry-common.h>
+
+#include <asm/asm-prototypes.h>
+#include <asm/unistd.h>
+#include <asm/processor.h>
+#include <asm/csr.h>
+#include <asm/stacktrace.h>
+#include <asm/string.h>
+#include <asm/switch_to.h>
+#include <asm/thread_info.h>
+#include <asm/cpuidle.h>
+#include <asm/vector.h>
+#include <asm/cpufeature.h>
+#include <asm/exec.h>
+
+#if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
+#include <linux/stackprotector.h>
+unsigned long __stack_chk_guard __read_mostly;
+EXPORT_SYMBOL(__stack_chk_guard);
+#endif
+
+extern asmlinkage void ret_from_fork_kernel_asm(void);
+extern asmlinkage void ret_from_fork_user_asm(void);
+
+void noinstr arch_cpu_idle(void)
+{
+	cpu_do_idle();
+}
+
+int set_unalign_ctl(struct task_struct *tsk, unsigned int val)
+{
+	if (!unaligned_ctl_available())
+		return -EINVAL;
+
+	tsk->thread.align_ctl = val;
+	return 0;
+}
+
+int get_unalign_ctl(struct task_struct *tsk, unsigned long adr)
+{
+	if (!unaligned_ctl_available())
+		return -EINVAL;
+
+	return put_user(tsk->thread.align_ctl, (unsigned int __user *)adr);
+}
+
+void __show_regs(struct pt_regs *regs)
+{
+	show_regs_print_info(KERN_DEFAULT);
+
+	if (!user_mode(regs)) {
+		pr_cont("epc : %pS\n", (void *)regs->epc);
+		pr_cont(" ra : %pS\n", (void *)regs->ra);
+	}
+
+	pr_cont("epc : " REG_FMT " ra : " REG_FMT " sp : " REG_FMT "\n",
+		regs->epc, regs->ra, regs->sp);
+	pr_cont(" gp : " REG_FMT " tp : " REG_FMT " t0 : " REG_FMT "\n",
+		regs->gp, regs->tp, regs->t0);
+	pr_cont(" t1 : " REG_FMT " t2 : " REG_FMT " s0 : " REG_FMT "\n",
+		regs->t1, regs->t2, regs->s0);
+	pr_cont(" s1 : " REG_FMT " a0 : " REG_FMT " a1 : " REG_FMT "\n",
+		regs->s1, regs->a0, regs->a1);
+	pr_cont(" a2 : " REG_FMT " a3 : " REG_FMT " a4 : " REG_FMT "\n",
+		regs->a2, regs->a3, regs->a4);
+	pr_cont(" a5 : " REG_FMT " a6 : " REG_FMT " a7 : " REG_FMT "\n",
+		regs->a5, regs->a6, regs->a7);
+	pr_cont(" s2 : " REG_FMT " s3 : " REG_FMT " s4 : " REG_FMT "\n",
+		regs->s2, regs->s3, regs->s4);
+	pr_cont(" s5 : " REG_FMT " s6 : " REG_FMT " s7 : " REG_FMT "\n",
+		regs->s5, regs->s6, regs->s7);
+	pr_cont(" s8 : " REG_FMT " s9 : " REG_FMT " s10: " REG_FMT "\n",
+		regs->s8, regs->s9, regs->s10);
+	pr_cont(" s11: " REG_FMT " t3 : " REG_FMT " t4 : " REG_FMT "\n",
+		regs->s11, regs->t3, regs->t4);
+	pr_cont(" t5 : " REG_FMT " t6 : " REG_FMT "\n",
+		regs->t5, regs->t6);
+
+	pr_cont("status: " REG_FMT " badaddr: " REG_FMT " cause: " REG_FMT "\n",
+		regs->status, regs->badaddr, regs->cause);
+}
+void show_regs(struct pt_regs *regs)
+{
+	__show_regs(regs);
+	if (!user_mode(regs))
+		dump_backtrace(regs, NULL, KERN_DEFAULT);
+}
+
+unsigned long arch_align_stack(unsigned long sp)
+{
+	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
+		sp -= get_random_u32_below(PAGE_SIZE);
+	return sp & ~0xf;
+}
+
+#ifdef CONFIG_COMPAT
+static bool compat_mode_supported __read_mostly;
+
+bool compat_elf_check_arch(Elf32_Ehdr *hdr)
+{
+	return compat_mode_supported &&
+	       hdr->e_machine == EM_RISCV &&
+	       hdr->e_ident[EI_CLASS] == ELFCLASS32;
+}
+
+static int __init compat_mode_detect(void)
+{
+	unsigned long tmp = csr_read(CSR_STATUS);
+
+	csr_write(CSR_STATUS, (tmp & ~SR_UXL) | SR_UXL_32);
+	compat_mode_supported =
+			(csr_read(CSR_STATUS) & SR_UXL) == SR_UXL_32;
+
+	csr_write(CSR_STATUS, tmp);
+
+	pr_info("riscv: ELF compat mode %s",
+			compat_mode_supported ? "supported" : "unsupported");
+
+	return 0;
+}
+early_initcall(compat_mode_detect);
+#endif
+
+void start_thread(struct pt_regs *regs, unsigned long pc,
+	unsigned long sp)
+{
+	regs->status = SR_PIE;
+	if (has_fpu()) {
+		regs->status |= SR_FS_INITIAL;
+		/*
+		 * Restore the initial value to the FP register
+		 * before starting the user program.
+		 */
+		fstate_restore(current, regs);
+	}
+	regs->epc = pc;
+	regs->sp = sp;
+
+#ifdef CONFIG_64BIT
+	regs->status &= ~SR_UXL;
+
+	if (is_compat_task())
+		regs->status |= SR_UXL_32;
+	else
+		regs->status |= SR_UXL_64;
+#endif
+}
+
+void flush_thread(void)
+{
+#ifdef CONFIG_FPU
+	/*
+	 * Reset FPU state and context
+	 *	frm: round to nearest, ties to even (IEEE default)
+	 *	fflags: accrued exceptions cleared
+	 */
+	fstate_off(current, task_pt_regs(current));
+	memset(&current->thread.fstate, 0, sizeof(current->thread.fstate));
+#endif
+#ifdef CONFIG_RISCV_ISA_V
+	/* Reset vector state */
+	riscv_v_vstate_ctrl_init(current);
+	riscv_v_vstate_off(task_pt_regs(current));
+	kfree(current->thread.vstate.datap);
+	memset(&current->thread.vstate, 0, sizeof(struct __riscv_v_ext_state));
+	clear_tsk_thread_flag(current, TIF_RISCV_V_DEFER_RESTORE);
+#endif
+#ifdef CONFIG_RISCV_ISA_SUPM
+	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM))
+		envcfg_update_bits(current, ENVCFG_PMM, ENVCFG_PMM_PMLEN_0);
+#endif
+}
+
+void arch_release_task_struct(struct task_struct *tsk)
+{
+	/* Free the vector context of datap. */
+	if (has_vector() || has_xtheadvector())
+		riscv_v_thread_free(tsk);
+}
+
+int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
+{
+	fstate_save(src, task_pt_regs(src));
+	*dst = *src;
+	/* clear entire V context, including datap for a new task */
+	memset(&dst->thread.vstate, 0, sizeof(struct __riscv_v_ext_state));
+	memset(&dst->thread.kernel_vstate, 0, sizeof(struct __riscv_v_ext_state));
+	clear_tsk_thread_flag(dst, TIF_RISCV_V_DEFER_RESTORE);
+
+	return 0;
+}
+
+asmlinkage void ret_from_fork_kernel(void *fn_arg, int (*fn)(void *), struct pt_regs *regs)
+{
+	fn(fn_arg);
+
+	syscall_exit_to_user_mode(regs);
+}
+
+asmlinkage void ret_from_fork_user(struct pt_regs *regs)
+{
+	syscall_exit_to_user_mode(regs);
+}
+
+int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
+{
+	u64 clone_flags = args->flags;
+	unsigned long usp = args->stack;
+	unsigned long tls = args->tls;
+	struct pt_regs *childregs = task_pt_regs(p);
+
+	/* Ensure all threads in this mm have the same pointer masking mode. */
+	if (IS_ENABLED(CONFIG_RISCV_ISA_SUPM) && p->mm && (clone_flags & CLONE_VM))
+		set_bit(MM_CONTEXT_LOCK_PMLEN, &p->mm->context.flags);
+
+	memset(&p->thread.s, 0, sizeof(p->thread.s));
+
+	/* p->thread holds context to be restored by __switch_to() */
+	if (unlikely(args->fn)) {
+		/* Kernel thread */
+		memset(childregs, 0, sizeof(struct pt_regs));
+		/* Supervisor/Machine, irqs on: */
+		childregs->status = SR_PP | SR_PIE;
+
+		p->thread.s[0] = (unsigned long)args->fn;
+		p->thread.s[1] = (unsigned long)args->fn_arg;
+		p->thread.ra = (unsigned long)ret_from_fork_kernel_asm;
+	} else {
+		*childregs = *(current_pt_regs());
+		/* Turn off status.VS */
+		riscv_v_vstate_off(childregs);
+		if (usp) /* User fork */
+			childregs->sp = usp;
+		if (clone_flags & CLONE_SETTLS)
+			childregs->tp = tls;
+		childregs->a0 = 0; /* Return value of fork() */
+		p->thread.ra = (unsigned long)ret_from_fork_user_asm;
+	}
+	p->thread.riscv_v_flags = 0;
+	if (has_vector() || has_xtheadvector())
+		riscv_v_thread_alloc(p);
+	p->thread.sp = (unsigned long)childregs; /* kernel sp */
+	return 0;
+}
+
+void __init arch_task_cache_init(void)
+{
+	riscv_v_setup_ctx_cache();
+}
+
+#ifdef CONFIG_RISCV_ISA_SUPM
+enum {
+	PMLEN_0 = 0,
+	PMLEN_7 = 7,
+	PMLEN_16 = 16,
+};
+
+static bool have_user_pmlen_7;
+static bool have_user_pmlen_16;
+
+/*
+ * Control the relaxed ABI allowing tagged user addresses into the kernel.
+ */
+static unsigned int tagged_addr_disabled;
+
+long set_tagged_addr_ctrl(struct task_struct *task, unsigned long arg)
+{
+	unsigned long valid_mask = PR_PMLEN_MASK | PR_TAGGED_ADDR_ENABLE;
+	struct thread_info *ti = task_thread_info(task);
+	struct mm_struct *mm = task->mm;
+	unsigned long pmm;
+	u8 pmlen;
+
+	if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM))
+		return -EINVAL;
+
+	if (is_compat_thread(ti))
+		return -EINVAL;
+
+	if (arg & ~valid_mask)
+		return -EINVAL;
+
+	/*
+	 * Prefer the smallest PMLEN that satisfies the user's request,
+	 * in case choosing a larger PMLEN has a performance impact.
+	 */
+	pmlen = FIELD_GET(PR_PMLEN_MASK, arg);
+	if (pmlen == PMLEN_0) {
+		pmm = ENVCFG_PMM_PMLEN_0;
+	} else if (pmlen <= PMLEN_7 && have_user_pmlen_7) {
+		pmlen = PMLEN_7;
+		pmm = ENVCFG_PMM_PMLEN_7;
+	} else if (pmlen <= PMLEN_16 && have_user_pmlen_16) {
+		pmlen = PMLEN_16;
+		pmm = ENVCFG_PMM_PMLEN_16;
+	} else {
+		return -EINVAL;
+	}
+
+	/*
+	 * Do not allow the enabling of the tagged address ABI if globally
+	 * disabled via sysctl abi.tagged_addr_disabled, if pointer masking
+	 * is disabled for userspace.
+	 */
+	if (arg & PR_TAGGED_ADDR_ENABLE && (tagged_addr_disabled || !pmlen))
+		return -EINVAL;
+
+	if (!(arg & PR_TAGGED_ADDR_ENABLE))
+		pmlen = PMLEN_0;
+
+	if (mmap_write_lock_killable(mm))
+		return -EINTR;
+
+	if (test_bit(MM_CONTEXT_LOCK_PMLEN, &mm->context.flags) && mm->context.pmlen != pmlen) {
+		mmap_write_unlock(mm);
+		return -EBUSY;
+	}
+
+	envcfg_update_bits(task, ENVCFG_PMM, pmm);
+	mm->context.pmlen = pmlen;
+
+	mmap_write_unlock(mm);
+
+	return 0;
+}
+
+long get_tagged_addr_ctrl(struct task_struct *task)
+{
+	struct thread_info *ti = task_thread_info(task);
+	long ret = 0;
+
+	if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM))
+		return -EINVAL;
+
+	if (is_compat_thread(ti))
+		return -EINVAL;
+
+	/*
+	 * The mm context's pmlen is set only when the tagged address ABI is
+	 * enabled, so the effective PMLEN must be extracted from envcfg.PMM.
+	 */
+	switch (task->thread.envcfg & ENVCFG_PMM) {
+	case ENVCFG_PMM_PMLEN_7:
+		ret = FIELD_PREP(PR_PMLEN_MASK, PMLEN_7);
+		break;
+	case ENVCFG_PMM_PMLEN_16:
+		ret = FIELD_PREP(PR_PMLEN_MASK, PMLEN_16);
+		break;
+	}
+
+	if (task->mm->context.pmlen)
+		ret |= PR_TAGGED_ADDR_ENABLE;
+
+	return ret;
+}
+
+static bool try_to_set_pmm(unsigned long value)
+{
+	csr_set(CSR_ENVCFG, value);
+	return (csr_read_clear(CSR_ENVCFG, ENVCFG_PMM) & ENVCFG_PMM) == value;
+}
+
+/*
+ * Global sysctl to disable the tagged user addresses support. This control
+ * only prevents the tagged address ABI enabling via prctl() and does not
+ * disable it for tasks that already opted in to the relaxed ABI.
+ */
+
+static const struct ctl_table tagged_addr_sysctl_table[] = {
+	{
+		.procname	= "tagged_addr_disabled",
+		.mode		= 0644,
+		.data		= &tagged_addr_disabled,
+		.maxlen		= sizeof(int),
+		.proc_handler	= proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+};
+
+static int __init tagged_addr_init(void)
+{
+	if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM))
+		return 0;
+
+	/*
+	 * envcfg.PMM is a WARL field. Detect which values are supported.
+	 * Assume the supported PMLEN values are the same on all harts.
+	 */
+	csr_clear(CSR_ENVCFG, ENVCFG_PMM);
+	have_user_pmlen_7 = try_to_set_pmm(ENVCFG_PMM_PMLEN_7);
+	have_user_pmlen_16 = try_to_set_pmm(ENVCFG_PMM_PMLEN_16);
+
+	if (!register_sysctl("abi", tagged_addr_sysctl_table))
+		return -EINVAL;
+
+	return 0;
+}
+core_initcall(tagged_addr_init);
+#endif	/* CONFIG_RISCV_ISA_SUPM */