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-rw-r--r--arch/riscv/kernel/probes/Makefile8
-rw-r--r--arch/riscv/kernel/probes/decode-insn.c47
-rw-r--r--arch/riscv/kernel/probes/decode-insn.h18
-rw-r--r--arch/riscv/kernel/probes/ftrace.c62
-rw-r--r--arch/riscv/kernel/probes/kprobes.c389
-rw-r--r--arch/riscv/kernel/probes/kprobes_trampoline.S93
-rw-r--r--arch/riscv/kernel/probes/simulate-insn.c197
-rw-r--r--arch/riscv/kernel/probes/simulate-insn.h47
-rw-r--r--arch/riscv/kernel/probes/uprobes.c182
9 files changed, 1043 insertions, 0 deletions
diff --git a/arch/riscv/kernel/probes/Makefile b/arch/riscv/kernel/probes/Makefile
new file mode 100644
index 000000000..90dea3abd
--- /dev/null
+++ b/arch/riscv/kernel/probes/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_KPROBES) += kprobes.o decode-insn.o simulate-insn.o
+obj-$(CONFIG_KPROBES) += kprobes_trampoline.o
+obj-$(CONFIG_KPROBES_ON_FTRACE) += ftrace.o
+obj-$(CONFIG_UPROBES) += uprobes.o decode-insn.o simulate-insn.o
+CFLAGS_REMOVE_simulate-insn.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_rethook.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_rethook_trampoline.o = $(CC_FLAGS_FTRACE)
diff --git a/arch/riscv/kernel/probes/decode-insn.c b/arch/riscv/kernel/probes/decode-insn.c
new file mode 100644
index 000000000..64f6183b4
--- /dev/null
+++ b/arch/riscv/kernel/probes/decode-insn.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+#include <linux/module.h>
+#include <linux/kallsyms.h>
+#include <asm/sections.h>
+
+#include "decode-insn.h"
+#include "simulate-insn.h"
+
+/* Return:
+ * INSN_REJECTED If instruction is one not allowed to kprobe,
+ * INSN_GOOD_NO_SLOT If instruction is supported but doesn't use its slot.
+ */
+enum probe_insn __kprobes
+riscv_probe_decode_insn(probe_opcode_t *addr, struct arch_probe_insn *api)
+{
+ probe_opcode_t insn = *addr;
+
+ /*
+ * Reject instructions list:
+ */
+ RISCV_INSN_REJECTED(system, insn);
+ RISCV_INSN_REJECTED(fence, insn);
+
+ /*
+ * Simulate instructions list:
+ * TODO: the REJECTED ones below need to be implemented
+ */
+#ifdef CONFIG_RISCV_ISA_C
+ RISCV_INSN_REJECTED(c_j, insn);
+ RISCV_INSN_REJECTED(c_jr, insn);
+ RISCV_INSN_REJECTED(c_jal, insn);
+ RISCV_INSN_REJECTED(c_jalr, insn);
+ RISCV_INSN_REJECTED(c_beqz, insn);
+ RISCV_INSN_REJECTED(c_bnez, insn);
+ RISCV_INSN_REJECTED(c_ebreak, insn);
+#endif
+
+ RISCV_INSN_SET_SIMULATE(jal, insn);
+ RISCV_INSN_SET_SIMULATE(jalr, insn);
+ RISCV_INSN_SET_SIMULATE(auipc, insn);
+ RISCV_INSN_SET_SIMULATE(branch, insn);
+
+ return INSN_GOOD;
+}
diff --git a/arch/riscv/kernel/probes/decode-insn.h b/arch/riscv/kernel/probes/decode-insn.h
new file mode 100644
index 000000000..42269a7d6
--- /dev/null
+++ b/arch/riscv/kernel/probes/decode-insn.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#ifndef _RISCV_KERNEL_KPROBES_DECODE_INSN_H
+#define _RISCV_KERNEL_KPROBES_DECODE_INSN_H
+
+#include <asm/sections.h>
+#include <asm/kprobes.h>
+
+enum probe_insn {
+ INSN_REJECTED,
+ INSN_GOOD_NO_SLOT,
+ INSN_GOOD,
+};
+
+enum probe_insn __kprobes
+riscv_probe_decode_insn(probe_opcode_t *addr, struct arch_probe_insn *asi);
+
+#endif /* _RISCV_KERNEL_KPROBES_DECODE_INSN_H */
diff --git a/arch/riscv/kernel/probes/ftrace.c b/arch/riscv/kernel/probes/ftrace.c
new file mode 100644
index 000000000..7142ec42e
--- /dev/null
+++ b/arch/riscv/kernel/probes/ftrace.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kprobes.h>
+
+/* Ftrace callback handler for kprobes -- called under preepmt disabled */
+void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
+ struct ftrace_ops *ops, struct ftrace_regs *fregs)
+{
+ struct kprobe *p;
+ struct pt_regs *regs;
+ struct kprobe_ctlblk *kcb;
+ int bit;
+
+ bit = ftrace_test_recursion_trylock(ip, parent_ip);
+ if (bit < 0)
+ return;
+
+ p = get_kprobe((kprobe_opcode_t *)ip);
+ if (unlikely(!p) || kprobe_disabled(p))
+ goto out;
+
+ regs = ftrace_get_regs(fregs);
+ kcb = get_kprobe_ctlblk();
+ if (kprobe_running()) {
+ kprobes_inc_nmissed_count(p);
+ } else {
+ unsigned long orig_ip = instruction_pointer(regs);
+
+ instruction_pointer_set(regs, ip);
+
+ __this_cpu_write(current_kprobe, p);
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+ if (!p->pre_handler || !p->pre_handler(p, regs)) {
+ /*
+ * Emulate singlestep (and also recover regs->pc)
+ * as if there is a nop
+ */
+ instruction_pointer_set(regs,
+ (unsigned long)p->addr + MCOUNT_INSN_SIZE);
+ if (unlikely(p->post_handler)) {
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ p->post_handler(p, regs, 0);
+ }
+ instruction_pointer_set(regs, orig_ip);
+ }
+
+ /*
+ * If pre_handler returns !0, it changes regs->pc. We have to
+ * skip emulating post_handler.
+ */
+ __this_cpu_write(current_kprobe, NULL);
+ }
+out:
+ ftrace_test_recursion_unlock(bit);
+}
+NOKPROBE_SYMBOL(kprobe_ftrace_handler);
+
+int arch_prepare_kprobe_ftrace(struct kprobe *p)
+{
+ p->ainsn.api.insn = NULL;
+ return 0;
+}
diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c
new file mode 100644
index 000000000..cca2b3a21
--- /dev/null
+++ b/arch/riscv/kernel/probes/kprobes.c
@@ -0,0 +1,389 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#define pr_fmt(fmt) "kprobes: " fmt
+
+#include <linux/kprobes.h>
+#include <linux/extable.h>
+#include <linux/slab.h>
+#include <linux/stop_machine.h>
+#include <asm/ptrace.h>
+#include <linux/uaccess.h>
+#include <asm/sections.h>
+#include <asm/cacheflush.h>
+#include <asm/bug.h>
+#include <asm/patch.h>
+
+#include "decode-insn.h"
+
+DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
+DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
+
+static void __kprobes
+post_kprobe_handler(struct kprobe *, struct kprobe_ctlblk *, struct pt_regs *);
+
+static void __kprobes arch_prepare_ss_slot(struct kprobe *p)
+{
+ unsigned long offset = GET_INSN_LENGTH(p->opcode);
+
+ p->ainsn.api.restore = (unsigned long)p->addr + offset;
+
+ patch_text(p->ainsn.api.insn, p->opcode);
+ patch_text((void *)((unsigned long)(p->ainsn.api.insn) + offset),
+ __BUG_INSN_32);
+}
+
+static void __kprobes arch_prepare_simulate(struct kprobe *p)
+{
+ p->ainsn.api.restore = 0;
+}
+
+static void __kprobes arch_simulate_insn(struct kprobe *p, struct pt_regs *regs)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ if (p->ainsn.api.handler)
+ p->ainsn.api.handler((u32)p->opcode,
+ (unsigned long)p->addr, regs);
+
+ post_kprobe_handler(p, kcb, regs);
+}
+
+static bool __kprobes arch_check_kprobe(struct kprobe *p)
+{
+ unsigned long tmp = (unsigned long)p->addr - p->offset;
+ unsigned long addr = (unsigned long)p->addr;
+
+ while (tmp <= addr) {
+ if (tmp == addr)
+ return true;
+
+ tmp += GET_INSN_LENGTH(*(u16 *)tmp);
+ }
+
+ return false;
+}
+
+int __kprobes arch_prepare_kprobe(struct kprobe *p)
+{
+ u16 *insn = (u16 *)p->addr;
+
+ if ((unsigned long)insn & 0x1)
+ return -EILSEQ;
+
+ if (!arch_check_kprobe(p))
+ return -EILSEQ;
+
+ /* copy instruction */
+ p->opcode = (kprobe_opcode_t)(*insn++);
+ if (GET_INSN_LENGTH(p->opcode) == 4)
+ p->opcode |= (kprobe_opcode_t)(*insn) << 16;
+
+ /* decode instruction */
+ switch (riscv_probe_decode_insn(p->addr, &p->ainsn.api)) {
+ case INSN_REJECTED: /* insn not supported */
+ return -EINVAL;
+
+ case INSN_GOOD_NO_SLOT: /* insn need simulation */
+ p->ainsn.api.insn = NULL;
+ break;
+
+ case INSN_GOOD: /* instruction uses slot */
+ p->ainsn.api.insn = get_insn_slot();
+ if (!p->ainsn.api.insn)
+ return -ENOMEM;
+ break;
+ }
+
+ /* prepare the instruction */
+ if (p->ainsn.api.insn)
+ arch_prepare_ss_slot(p);
+ else
+ arch_prepare_simulate(p);
+
+ return 0;
+}
+
+#ifdef CONFIG_MMU
+void *alloc_insn_page(void)
+{
+ return __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START, VMALLOC_END,
+ GFP_KERNEL, PAGE_KERNEL_READ_EXEC,
+ VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
+ __builtin_return_address(0));
+}
+#endif
+
+/* install breakpoint in text */
+void __kprobes arch_arm_kprobe(struct kprobe *p)
+{
+ if ((p->opcode & __INSN_LENGTH_MASK) == __INSN_LENGTH_32)
+ patch_text(p->addr, __BUG_INSN_32);
+ else
+ patch_text(p->addr, __BUG_INSN_16);
+}
+
+/* remove breakpoint from text */
+void __kprobes arch_disarm_kprobe(struct kprobe *p)
+{
+ patch_text(p->addr, p->opcode);
+}
+
+void __kprobes arch_remove_kprobe(struct kprobe *p)
+{
+}
+
+static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ kcb->prev_kprobe.kp = kprobe_running();
+ kcb->prev_kprobe.status = kcb->kprobe_status;
+}
+
+static void __kprobes restore_previous_kprobe(struct kprobe_ctlblk *kcb)
+{
+ __this_cpu_write(current_kprobe, kcb->prev_kprobe.kp);
+ kcb->kprobe_status = kcb->prev_kprobe.status;
+}
+
+static void __kprobes set_current_kprobe(struct kprobe *p)
+{
+ __this_cpu_write(current_kprobe, p);
+}
+
+/*
+ * Interrupts need to be disabled before single-step mode is set, and not
+ * reenabled until after single-step mode ends.
+ * Without disabling interrupt on local CPU, there is a chance of
+ * interrupt occurrence in the period of exception return and start of
+ * out-of-line single-step, that result in wrongly single stepping
+ * into the interrupt handler.
+ */
+static void __kprobes kprobes_save_local_irqflag(struct kprobe_ctlblk *kcb,
+ struct pt_regs *regs)
+{
+ kcb->saved_status = regs->status;
+ regs->status &= ~SR_SPIE;
+}
+
+static void __kprobes kprobes_restore_local_irqflag(struct kprobe_ctlblk *kcb,
+ struct pt_regs *regs)
+{
+ regs->status = kcb->saved_status;
+}
+
+static void __kprobes setup_singlestep(struct kprobe *p,
+ struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb, int reenter)
+{
+ unsigned long slot;
+
+ if (reenter) {
+ save_previous_kprobe(kcb);
+ set_current_kprobe(p);
+ kcb->kprobe_status = KPROBE_REENTER;
+ } else {
+ kcb->kprobe_status = KPROBE_HIT_SS;
+ }
+
+ if (p->ainsn.api.insn) {
+ /* prepare for single stepping */
+ slot = (unsigned long)p->ainsn.api.insn;
+
+ /* IRQs and single stepping do not mix well. */
+ kprobes_save_local_irqflag(kcb, regs);
+
+ instruction_pointer_set(regs, slot);
+ } else {
+ /* insn simulation */
+ arch_simulate_insn(p, regs);
+ }
+}
+
+static int __kprobes reenter_kprobe(struct kprobe *p,
+ struct pt_regs *regs,
+ struct kprobe_ctlblk *kcb)
+{
+ switch (kcb->kprobe_status) {
+ case KPROBE_HIT_SSDONE:
+ case KPROBE_HIT_ACTIVE:
+ kprobes_inc_nmissed_count(p);
+ setup_singlestep(p, regs, kcb, 1);
+ break;
+ case KPROBE_HIT_SS:
+ case KPROBE_REENTER:
+ pr_warn("Failed to recover from reentered kprobes.\n");
+ dump_kprobe(p);
+ BUG();
+ break;
+ default:
+ WARN_ON(1);
+ return 0;
+ }
+
+ return 1;
+}
+
+static void __kprobes
+post_kprobe_handler(struct kprobe *cur, struct kprobe_ctlblk *kcb, struct pt_regs *regs)
+{
+ /* return addr restore if non-branching insn */
+ if (cur->ainsn.api.restore != 0)
+ regs->epc = cur->ainsn.api.restore;
+
+ /* restore back original saved kprobe variables and continue */
+ if (kcb->kprobe_status == KPROBE_REENTER) {
+ restore_previous_kprobe(kcb);
+ return;
+ }
+
+ /* call post handler */
+ kcb->kprobe_status = KPROBE_HIT_SSDONE;
+ if (cur->post_handler) {
+ /* post_handler can hit breakpoint and single step
+ * again, so we enable D-flag for recursive exception.
+ */
+ cur->post_handler(cur, regs, 0);
+ }
+
+ reset_current_kprobe();
+}
+
+int __kprobes kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr)
+{
+ struct kprobe *cur = kprobe_running();
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+
+ switch (kcb->kprobe_status) {
+ case KPROBE_HIT_SS:
+ case KPROBE_REENTER:
+ /*
+ * We are here because the instruction being single
+ * stepped caused a page fault. We reset the current
+ * kprobe and the ip points back to the probe address
+ * and allow the page fault handler to continue as a
+ * normal page fault.
+ */
+ regs->epc = (unsigned long) cur->addr;
+ BUG_ON(!instruction_pointer(regs));
+
+ if (kcb->kprobe_status == KPROBE_REENTER)
+ restore_previous_kprobe(kcb);
+ else {
+ kprobes_restore_local_irqflag(kcb, regs);
+ reset_current_kprobe();
+ }
+
+ break;
+ case KPROBE_HIT_ACTIVE:
+ case KPROBE_HIT_SSDONE:
+ /*
+ * In case the user-specified fault handler returned
+ * zero, try to fix up.
+ */
+ if (fixup_exception(regs))
+ return 1;
+ }
+ return 0;
+}
+
+bool __kprobes
+kprobe_breakpoint_handler(struct pt_regs *regs)
+{
+ struct kprobe *p, *cur_kprobe;
+ struct kprobe_ctlblk *kcb;
+ unsigned long addr = instruction_pointer(regs);
+
+ kcb = get_kprobe_ctlblk();
+ cur_kprobe = kprobe_running();
+
+ p = get_kprobe((kprobe_opcode_t *) addr);
+
+ if (p) {
+ if (cur_kprobe) {
+ if (reenter_kprobe(p, regs, kcb))
+ return true;
+ } else {
+ /* Probe hit */
+ set_current_kprobe(p);
+ kcb->kprobe_status = KPROBE_HIT_ACTIVE;
+
+ /*
+ * If we have no pre-handler or it returned 0, we
+ * continue with normal processing. If we have a
+ * pre-handler and it returned non-zero, it will
+ * modify the execution path and no need to single
+ * stepping. Let's just reset current kprobe and exit.
+ *
+ * pre_handler can hit a breakpoint and can step thru
+ * before return.
+ */
+ if (!p->pre_handler || !p->pre_handler(p, regs))
+ setup_singlestep(p, regs, kcb, 0);
+ else
+ reset_current_kprobe();
+ }
+ return true;
+ }
+
+ /*
+ * The breakpoint instruction was removed right
+ * after we hit it. Another cpu has removed
+ * either a probepoint or a debugger breakpoint
+ * at this address. In either case, no further
+ * handling of this interrupt is appropriate.
+ * Return back to original instruction, and continue.
+ */
+ return false;
+}
+
+bool __kprobes
+kprobe_single_step_handler(struct pt_regs *regs)
+{
+ struct kprobe_ctlblk *kcb = get_kprobe_ctlblk();
+ unsigned long addr = instruction_pointer(regs);
+ struct kprobe *cur = kprobe_running();
+
+ if (cur && (kcb->kprobe_status & (KPROBE_HIT_SS | KPROBE_REENTER)) &&
+ ((unsigned long)&cur->ainsn.api.insn[0] + GET_INSN_LENGTH(cur->opcode) == addr)) {
+ kprobes_restore_local_irqflag(kcb, regs);
+ post_kprobe_handler(cur, kcb, regs);
+ return true;
+ }
+ /* not ours, kprobes should ignore it */
+ return false;
+}
+
+/*
+ * Provide a blacklist of symbols identifying ranges which cannot be kprobed.
+ * This blacklist is exposed to userspace via debugfs (kprobes/blacklist).
+ */
+int __init arch_populate_kprobe_blacklist(void)
+{
+ int ret;
+
+ ret = kprobe_add_area_blacklist((unsigned long)__irqentry_text_start,
+ (unsigned long)__irqentry_text_end);
+ return ret;
+}
+
+void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
+{
+ return (void *)kretprobe_trampoline_handler(regs, NULL);
+}
+
+void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
+ struct pt_regs *regs)
+{
+ ri->ret_addr = (kprobe_opcode_t *)regs->ra;
+ ri->fp = NULL;
+ regs->ra = (unsigned long) &__kretprobe_trampoline;
+}
+
+int __kprobes arch_trampoline_kprobe(struct kprobe *p)
+{
+ return 0;
+}
+
+int __init arch_init_kprobes(void)
+{
+ return 0;
+}
diff --git a/arch/riscv/kernel/probes/kprobes_trampoline.S b/arch/riscv/kernel/probes/kprobes_trampoline.S
new file mode 100644
index 000000000..7bdb09ded
--- /dev/null
+++ b/arch/riscv/kernel/probes/kprobes_trampoline.S
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Author: Patrick Stählin <me@packi.ch>
+ */
+#include <linux/linkage.h>
+
+#include <asm/asm.h>
+#include <asm/asm-offsets.h>
+
+ .text
+ .altmacro
+
+ .macro save_all_base_regs
+ REG_S x1, PT_RA(sp)
+ REG_S x3, PT_GP(sp)
+ REG_S x4, PT_TP(sp)
+ REG_S x5, PT_T0(sp)
+ REG_S x6, PT_T1(sp)
+ REG_S x7, PT_T2(sp)
+ REG_S x8, PT_S0(sp)
+ REG_S x9, PT_S1(sp)
+ REG_S x10, PT_A0(sp)
+ REG_S x11, PT_A1(sp)
+ REG_S x12, PT_A2(sp)
+ REG_S x13, PT_A3(sp)
+ REG_S x14, PT_A4(sp)
+ REG_S x15, PT_A5(sp)
+ REG_S x16, PT_A6(sp)
+ REG_S x17, PT_A7(sp)
+ REG_S x18, PT_S2(sp)
+ REG_S x19, PT_S3(sp)
+ REG_S x20, PT_S4(sp)
+ REG_S x21, PT_S5(sp)
+ REG_S x22, PT_S6(sp)
+ REG_S x23, PT_S7(sp)
+ REG_S x24, PT_S8(sp)
+ REG_S x25, PT_S9(sp)
+ REG_S x26, PT_S10(sp)
+ REG_S x27, PT_S11(sp)
+ REG_S x28, PT_T3(sp)
+ REG_S x29, PT_T4(sp)
+ REG_S x30, PT_T5(sp)
+ REG_S x31, PT_T6(sp)
+ .endm
+
+ .macro restore_all_base_regs
+ REG_L x3, PT_GP(sp)
+ REG_L x4, PT_TP(sp)
+ REG_L x5, PT_T0(sp)
+ REG_L x6, PT_T1(sp)
+ REG_L x7, PT_T2(sp)
+ REG_L x8, PT_S0(sp)
+ REG_L x9, PT_S1(sp)
+ REG_L x10, PT_A0(sp)
+ REG_L x11, PT_A1(sp)
+ REG_L x12, PT_A2(sp)
+ REG_L x13, PT_A3(sp)
+ REG_L x14, PT_A4(sp)
+ REG_L x15, PT_A5(sp)
+ REG_L x16, PT_A6(sp)
+ REG_L x17, PT_A7(sp)
+ REG_L x18, PT_S2(sp)
+ REG_L x19, PT_S3(sp)
+ REG_L x20, PT_S4(sp)
+ REG_L x21, PT_S5(sp)
+ REG_L x22, PT_S6(sp)
+ REG_L x23, PT_S7(sp)
+ REG_L x24, PT_S8(sp)
+ REG_L x25, PT_S9(sp)
+ REG_L x26, PT_S10(sp)
+ REG_L x27, PT_S11(sp)
+ REG_L x28, PT_T3(sp)
+ REG_L x29, PT_T4(sp)
+ REG_L x30, PT_T5(sp)
+ REG_L x31, PT_T6(sp)
+ .endm
+
+ENTRY(__kretprobe_trampoline)
+ addi sp, sp, -(PT_SIZE_ON_STACK)
+ save_all_base_regs
+
+ move a0, sp /* pt_regs */
+
+ call trampoline_probe_handler
+
+ /* use the result as the return-address */
+ move ra, a0
+
+ restore_all_base_regs
+ addi sp, sp, PT_SIZE_ON_STACK
+
+ ret
+ENDPROC(__kretprobe_trampoline)
diff --git a/arch/riscv/kernel/probes/simulate-insn.c b/arch/riscv/kernel/probes/simulate-insn.c
new file mode 100644
index 000000000..41bf1eb01
--- /dev/null
+++ b/arch/riscv/kernel/probes/simulate-insn.c
@@ -0,0 +1,197 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/kprobes.h>
+
+#include "decode-insn.h"
+#include "simulate-insn.h"
+
+static inline bool rv_insn_reg_get_val(struct pt_regs *regs, u32 index,
+ unsigned long *ptr)
+{
+ if (index == 0)
+ *ptr = 0;
+ else if (index <= 31)
+ *ptr = *((unsigned long *)regs + index);
+ else
+ return false;
+
+ return true;
+}
+
+static inline bool rv_insn_reg_set_val(struct pt_regs *regs, u32 index,
+ unsigned long val)
+{
+ if (index == 0)
+ return true;
+ else if (index <= 31)
+ *((unsigned long *)regs + index) = val;
+ else
+ return false;
+
+ return true;
+}
+
+bool __kprobes simulate_jal(u32 opcode, unsigned long addr, struct pt_regs *regs)
+{
+ /*
+ * 31 30 21 20 19 12 11 7 6 0
+ * imm [20] | imm[10:1] | imm[11] | imm[19:12] | rd | opcode
+ * 1 10 1 8 5 JAL/J
+ */
+ bool ret;
+ u32 imm;
+ u32 index = (opcode >> 7) & 0x1f;
+
+ ret = rv_insn_reg_set_val(regs, index, addr + 4);
+ if (!ret)
+ return ret;
+
+ imm = ((opcode >> 21) & 0x3ff) << 1;
+ imm |= ((opcode >> 20) & 0x1) << 11;
+ imm |= ((opcode >> 12) & 0xff) << 12;
+ imm |= ((opcode >> 31) & 0x1) << 20;
+
+ instruction_pointer_set(regs, addr + sign_extend32((imm), 20));
+
+ return ret;
+}
+
+bool __kprobes simulate_jalr(u32 opcode, unsigned long addr, struct pt_regs *regs)
+{
+ /*
+ * 31 20 19 15 14 12 11 7 6 0
+ * offset[11:0] | rs1 | 010 | rd | opcode
+ * 12 5 3 5 JALR/JR
+ */
+ bool ret;
+ unsigned long base_addr;
+ u32 imm = (opcode >> 20) & 0xfff;
+ u32 rd_index = (opcode >> 7) & 0x1f;
+ u32 rs1_index = (opcode >> 15) & 0x1f;
+
+ ret = rv_insn_reg_get_val(regs, rs1_index, &base_addr);
+ if (!ret)
+ return ret;
+
+ ret = rv_insn_reg_set_val(regs, rd_index, addr + 4);
+ if (!ret)
+ return ret;
+
+ instruction_pointer_set(regs, (base_addr + sign_extend32((imm), 11))&~1);
+
+ return ret;
+}
+
+#define auipc_rd_idx(opcode) \
+ ((opcode >> 7) & 0x1f)
+
+#define auipc_imm(opcode) \
+ ((((opcode) >> 12) & 0xfffff) << 12)
+
+#if __riscv_xlen == 64
+#define auipc_offset(opcode) sign_extend64(auipc_imm(opcode), 31)
+#elif __riscv_xlen == 32
+#define auipc_offset(opcode) auipc_imm(opcode)
+#else
+#error "Unexpected __riscv_xlen"
+#endif
+
+bool __kprobes simulate_auipc(u32 opcode, unsigned long addr, struct pt_regs *regs)
+{
+ /*
+ * auipc instruction:
+ * 31 12 11 7 6 0
+ * | imm[31:12] | rd | opcode |
+ * 20 5 7
+ */
+
+ u32 rd_idx = auipc_rd_idx(opcode);
+ unsigned long rd_val = addr + auipc_offset(opcode);
+
+ if (!rv_insn_reg_set_val(regs, rd_idx, rd_val))
+ return false;
+
+ instruction_pointer_set(regs, addr + 4);
+
+ return true;
+}
+
+#define branch_rs1_idx(opcode) \
+ (((opcode) >> 15) & 0x1f)
+
+#define branch_rs2_idx(opcode) \
+ (((opcode) >> 20) & 0x1f)
+
+#define branch_funct3(opcode) \
+ (((opcode) >> 12) & 0x7)
+
+#define branch_imm(opcode) \
+ (((((opcode) >> 8) & 0xf ) << 1) | \
+ ((((opcode) >> 25) & 0x3f) << 5) | \
+ ((((opcode) >> 7) & 0x1 ) << 11) | \
+ ((((opcode) >> 31) & 0x1 ) << 12))
+
+#define branch_offset(opcode) \
+ sign_extend32((branch_imm(opcode)), 12)
+
+#define BRANCH_BEQ 0x0
+#define BRANCH_BNE 0x1
+#define BRANCH_BLT 0x4
+#define BRANCH_BGE 0x5
+#define BRANCH_BLTU 0x6
+#define BRANCH_BGEU 0x7
+
+bool __kprobes simulate_branch(u32 opcode, unsigned long addr, struct pt_regs *regs)
+{
+ /*
+ * branch instructions:
+ * 31 30 25 24 20 19 15 14 12 11 8 7 6 0
+ * | imm[12] | imm[10:5] | rs2 | rs1 | funct3 | imm[4:1] | imm[11] | opcode |
+ * 1 6 5 5 3 4 1 7
+ * imm[12|10:5] rs2 rs1 000 imm[4:1|11] 1100011 BEQ
+ * imm[12|10:5] rs2 rs1 001 imm[4:1|11] 1100011 BNE
+ * imm[12|10:5] rs2 rs1 100 imm[4:1|11] 1100011 BLT
+ * imm[12|10:5] rs2 rs1 101 imm[4:1|11] 1100011 BGE
+ * imm[12|10:5] rs2 rs1 110 imm[4:1|11] 1100011 BLTU
+ * imm[12|10:5] rs2 rs1 111 imm[4:1|11] 1100011 BGEU
+ */
+
+ s32 offset;
+ s32 offset_tmp;
+ unsigned long rs1_val;
+ unsigned long rs2_val;
+
+ if (!rv_insn_reg_get_val(regs, branch_rs1_idx(opcode), &rs1_val) ||
+ !rv_insn_reg_get_val(regs, branch_rs2_idx(opcode), &rs2_val))
+ return false;
+
+ offset_tmp = branch_offset(opcode);
+ switch (branch_funct3(opcode)) {
+ case BRANCH_BEQ:
+ offset = (rs1_val == rs2_val) ? offset_tmp : 4;
+ break;
+ case BRANCH_BNE:
+ offset = (rs1_val != rs2_val) ? offset_tmp : 4;
+ break;
+ case BRANCH_BLT:
+ offset = ((long)rs1_val < (long)rs2_val) ? offset_tmp : 4;
+ break;
+ case BRANCH_BGE:
+ offset = ((long)rs1_val >= (long)rs2_val) ? offset_tmp : 4;
+ break;
+ case BRANCH_BLTU:
+ offset = (rs1_val < rs2_val) ? offset_tmp : 4;
+ break;
+ case BRANCH_BGEU:
+ offset = (rs1_val >= rs2_val) ? offset_tmp : 4;
+ break;
+ default:
+ return false;
+ }
+
+ instruction_pointer_set(regs, addr + offset);
+
+ return true;
+}
diff --git a/arch/riscv/kernel/probes/simulate-insn.h b/arch/riscv/kernel/probes/simulate-insn.h
new file mode 100644
index 000000000..de8474146
--- /dev/null
+++ b/arch/riscv/kernel/probes/simulate-insn.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+
+#ifndef _RISCV_KERNEL_PROBES_SIMULATE_INSN_H
+#define _RISCV_KERNEL_PROBES_SIMULATE_INSN_H
+
+#define __RISCV_INSN_FUNCS(name, mask, val) \
+static __always_inline bool riscv_insn_is_##name(probe_opcode_t code) \
+{ \
+ BUILD_BUG_ON(~(mask) & (val)); \
+ return (code & (mask)) == (val); \
+} \
+bool simulate_##name(u32 opcode, unsigned long addr, \
+ struct pt_regs *regs)
+
+#define RISCV_INSN_REJECTED(name, code) \
+ do { \
+ if (riscv_insn_is_##name(code)) { \
+ return INSN_REJECTED; \
+ } \
+ } while (0)
+
+__RISCV_INSN_FUNCS(system, 0x7f, 0x73);
+__RISCV_INSN_FUNCS(fence, 0x7f, 0x0f);
+
+#define RISCV_INSN_SET_SIMULATE(name, code) \
+ do { \
+ if (riscv_insn_is_##name(code)) { \
+ api->handler = simulate_##name; \
+ return INSN_GOOD_NO_SLOT; \
+ } \
+ } while (0)
+
+__RISCV_INSN_FUNCS(c_j, 0xe003, 0xa001);
+__RISCV_INSN_FUNCS(c_jr, 0xf07f, 0x8002);
+__RISCV_INSN_FUNCS(c_jal, 0xe003, 0x2001);
+__RISCV_INSN_FUNCS(c_jalr, 0xf07f, 0x9002);
+__RISCV_INSN_FUNCS(c_beqz, 0xe003, 0xc001);
+__RISCV_INSN_FUNCS(c_bnez, 0xe003, 0xe001);
+__RISCV_INSN_FUNCS(c_ebreak, 0xffff, 0x9002);
+
+__RISCV_INSN_FUNCS(auipc, 0x7f, 0x17);
+__RISCV_INSN_FUNCS(branch, 0x7f, 0x63);
+
+__RISCV_INSN_FUNCS(jal, 0x7f, 0x6f);
+__RISCV_INSN_FUNCS(jalr, 0x707f, 0x67);
+
+#endif /* _RISCV_KERNEL_PROBES_SIMULATE_INSN_H */
diff --git a/arch/riscv/kernel/probes/uprobes.c b/arch/riscv/kernel/probes/uprobes.c
new file mode 100644
index 000000000..194f166b2
--- /dev/null
+++ b/arch/riscv/kernel/probes/uprobes.c
@@ -0,0 +1,182 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/highmem.h>
+#include <linux/ptrace.h>
+#include <linux/uprobes.h>
+
+#include "decode-insn.h"
+
+#define UPROBE_TRAP_NR UINT_MAX
+
+bool is_swbp_insn(uprobe_opcode_t *insn)
+{
+#ifdef CONFIG_RISCV_ISA_C
+ return (*insn & 0xffff) == UPROBE_SWBP_INSN;
+#else
+ return *insn == UPROBE_SWBP_INSN;
+#endif
+}
+
+unsigned long uprobe_get_swbp_addr(struct pt_regs *regs)
+{
+ return instruction_pointer(regs);
+}
+
+int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
+ unsigned long addr)
+{
+ probe_opcode_t opcode;
+
+ opcode = *(probe_opcode_t *)(&auprobe->insn[0]);
+
+ auprobe->insn_size = GET_INSN_LENGTH(opcode);
+
+ switch (riscv_probe_decode_insn(&opcode, &auprobe->api)) {
+ case INSN_REJECTED:
+ return -EINVAL;
+
+ case INSN_GOOD_NO_SLOT:
+ auprobe->simulate = true;
+ break;
+
+ case INSN_GOOD:
+ auprobe->simulate = false;
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+int arch_uprobe_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ utask->autask.saved_cause = current->thread.bad_cause;
+ current->thread.bad_cause = UPROBE_TRAP_NR;
+
+ instruction_pointer_set(regs, utask->xol_vaddr);
+
+ return 0;
+}
+
+int arch_uprobe_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ WARN_ON_ONCE(current->thread.bad_cause != UPROBE_TRAP_NR);
+ current->thread.bad_cause = utask->autask.saved_cause;
+
+ instruction_pointer_set(regs, utask->vaddr + auprobe->insn_size);
+
+ return 0;
+}
+
+bool arch_uprobe_xol_was_trapped(struct task_struct *t)
+{
+ if (t->thread.bad_cause != UPROBE_TRAP_NR)
+ return true;
+
+ return false;
+}
+
+bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ probe_opcode_t insn;
+ unsigned long addr;
+
+ if (!auprobe->simulate)
+ return false;
+
+ insn = *(probe_opcode_t *)(&auprobe->insn[0]);
+ addr = instruction_pointer(regs);
+
+ if (auprobe->api.handler)
+ auprobe->api.handler(insn, addr, regs);
+
+ return true;
+}
+
+void arch_uprobe_abort_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ current->thread.bad_cause = utask->autask.saved_cause;
+ /*
+ * Task has received a fatal signal, so reset back to probbed
+ * address.
+ */
+ instruction_pointer_set(regs, utask->vaddr);
+}
+
+bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,
+ struct pt_regs *regs)
+{
+ if (ctx == RP_CHECK_CHAIN_CALL)
+ return regs->sp <= ret->stack;
+ else
+ return regs->sp < ret->stack;
+}
+
+unsigned long
+arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr,
+ struct pt_regs *regs)
+{
+ unsigned long ra;
+
+ ra = regs->ra;
+
+ regs->ra = trampoline_vaddr;
+
+ return ra;
+}
+
+int arch_uprobe_exception_notify(struct notifier_block *self,
+ unsigned long val, void *data)
+{
+ return NOTIFY_DONE;
+}
+
+bool uprobe_breakpoint_handler(struct pt_regs *regs)
+{
+ if (uprobe_pre_sstep_notifier(regs))
+ return true;
+
+ return false;
+}
+
+bool uprobe_single_step_handler(struct pt_regs *regs)
+{
+ if (uprobe_post_sstep_notifier(regs))
+ return true;
+
+ return false;
+}
+
+void arch_uprobe_copy_ixol(struct page *page, unsigned long vaddr,
+ void *src, unsigned long len)
+{
+ /* Initialize the slot */
+ void *kaddr = kmap_atomic(page);
+ void *dst = kaddr + (vaddr & ~PAGE_MASK);
+
+ memcpy(dst, src, len);
+
+ /* Add ebreak behind opcode to simulate singlestep */
+ if (vaddr) {
+ dst += GET_INSN_LENGTH(*(probe_opcode_t *)src);
+ *(uprobe_opcode_t *)dst = __BUG_INSN_32;
+ }
+
+ kunmap_atomic(kaddr);
+
+ /*
+ * We probably need flush_icache_user_page() but it needs vma.
+ * This should work on most of architectures by default. If
+ * architecture needs to do something different it can define
+ * its own version of the function.
+ */
+ flush_dcache_page(page);
+}
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