arch/riscv/kernel/ptrace.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 * Copyright 2015 Regents of the University of California
 * Copyright 2017 SiFive
 *
 * Copied from arch/tile/kernel/ptrace.c
 */

#include <asm/ptrace.h>
#include <asm/syscall.h>
#include <asm/thread_info.h>
#include <linux/audit.h>
#include <linux/ptrace.h>
#include <linux/elf.h>
#include <linux/regset.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/tracehook.h>

#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>

enum riscv_regset {
	REGSET_X,
#ifdef CONFIG_FPU
	REGSET_F,
#endif
};

static int riscv_gpr_get(struct task_struct *target,
			 const struct user_regset *regset,
			 struct membuf to)
{
	return membuf_write(&to, task_pt_regs(target),
			    sizeof(struct user_regs_struct));
}

static int riscv_gpr_set(struct task_struct *target,
			 const struct user_regset *regset,
			 unsigned int pos, unsigned int count,
			 const void *kbuf, const void __user *ubuf)
{
	int ret;
	struct pt_regs *regs;

	regs = task_pt_regs(target);
	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, regs, 0, -1);
	return ret;
}

#ifdef CONFIG_FPU
static int riscv_fpr_get(struct task_struct *target,
			 const struct user_regset *regset,
			 struct membuf to)
{
	struct __riscv_d_ext_state *fstate = &target->thread.fstate;

	membuf_write(&to, fstate, offsetof(struct __riscv_d_ext_state, fcsr));
	membuf_store(&to, fstate->fcsr);
	return membuf_zero(&to, 4);	// explicitly pad
}

static int riscv_fpr_set(struct task_struct *target,
			 const struct user_regset *regset,
			 unsigned int pos, unsigned int count,
			 const void *kbuf, const void __user *ubuf)
{
	int ret;
	struct __riscv_d_ext_state *fstate = &target->thread.fstate;

	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, fstate, 0,
				 offsetof(struct __riscv_d_ext_state, fcsr));
	if (!ret) {
		ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, fstate, 0,
					 offsetof(struct __riscv_d_ext_state, fcsr) +
					 sizeof(fstate->fcsr));
	}

	return ret;
}
#endif

static const struct user_regset riscv_user_regset[] = {
	[REGSET_X] = {
		.core_note_type = NT_PRSTATUS,
		.n = ELF_NGREG,
		.size = sizeof(elf_greg_t),
		.align = sizeof(elf_greg_t),
		.regset_get = riscv_gpr_get,
		.set = riscv_gpr_set,
	},
#ifdef CONFIG_FPU
	[REGSET_F] = {
		.core_note_type = NT_PRFPREG,
		.n = ELF_NFPREG,
		.size = sizeof(elf_fpreg_t),
		.align = sizeof(elf_fpreg_t),
		.regset_get = riscv_fpr_get,
		.set = riscv_fpr_set,
	},
#endif
};

static const struct user_regset_view riscv_user_native_view = {
	.name = "riscv",
	.e_machine = EM_RISCV,
	.regsets = riscv_user_regset,
	.n = ARRAY_SIZE(riscv_user_regset),
};

const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
	return &riscv_user_native_view;
}

void ptrace_disable(struct task_struct *child)
{
	clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
}

long arch_ptrace(struct task_struct *child, long request,
		 unsigned long addr, unsigned long data)
{
	long ret = -EIO;

	switch (request) {
	default:
		ret = ptrace_request(child, request, addr, data);
		break;
	}

	return ret;
}

/*
 * Allows PTRACE_SYSCALL to work.  These are called from entry.S in
 * {handle,ret_from}_syscall.
 */
__visible int do_syscall_trace_enter(struct pt_regs *regs)
{
	if (test_thread_flag(TIF_SYSCALL_TRACE))
		if (tracehook_report_syscall_entry(regs))
			return -1;

	/*
	 * Do the secure computing after ptrace; failures should be fast.
	 * If this fails we might have return value in a0 from seccomp
	 * (via SECCOMP_RET_ERRNO/TRACE).
	 */
	if (secure_computing() == -1)
		return -1;

#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
		trace_sys_enter(regs, syscall_get_nr(current, regs));
#endif

	audit_syscall_entry(regs->a7, regs->a0, regs->a1, regs->a2, regs->a3);
	return 0;
}

__visible void do_syscall_trace_exit(struct pt_regs *regs)
{
	audit_syscall_exit(regs);

	if (test_thread_flag(TIF_SYSCALL_TRACE))
		tracehook_report_syscall_exit(regs, 0);

#ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS
	if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
		trace_sys_exit(regs, regs_return_value(regs));
#endif
}