![Pratyush Anand](/assets/img/avatar_default.png)
This patch adds support for uprobe on ARM64 architecture. Unit tests for following have been done so far and they have been found working 1. Step-able instructions, like sub, ldr, add etc. 2. Simulation-able like ret, cbnz, cbz etc. 3. uretprobe 4. Reject-able instructions like sev, wfe etc. 5. trapped and abort xol path 6. probe at unaligned user address. 7. longjump test cases Currently it does not support aarch32 instruction probing. Signed-off-by: Pratyush Anand <panand@redhat.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
436 lines
11 KiB
C
436 lines
11 KiB
C
/*
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* Based on arch/arm/kernel/signal.c
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*
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* Copyright (C) 1995-2009 Russell King
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* Copyright (C) 2012 ARM Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/compat.h>
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#include <linux/errno.h>
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#include <linux/signal.h>
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#include <linux/personality.h>
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#include <linux/freezer.h>
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#include <linux/uaccess.h>
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#include <linux/tracehook.h>
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#include <linux/ratelimit.h>
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#include <asm/debug-monitors.h>
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#include <asm/elf.h>
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#include <asm/cacheflush.h>
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#include <asm/ucontext.h>
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#include <asm/unistd.h>
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#include <asm/fpsimd.h>
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#include <asm/signal32.h>
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#include <asm/vdso.h>
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/*
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* Do a signal return; undo the signal stack. These are aligned to 128-bit.
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*/
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struct rt_sigframe {
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struct siginfo info;
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struct ucontext uc;
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u64 fp;
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u64 lr;
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};
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static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
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{
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struct fpsimd_state *fpsimd = ¤t->thread.fpsimd_state;
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int err;
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/* dump the hardware registers to the fpsimd_state structure */
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fpsimd_preserve_current_state();
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/* copy the FP and status/control registers */
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err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs));
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__put_user_error(fpsimd->fpsr, &ctx->fpsr, err);
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__put_user_error(fpsimd->fpcr, &ctx->fpcr, err);
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/* copy the magic/size information */
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__put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err);
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__put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err);
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return err ? -EFAULT : 0;
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}
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static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
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{
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struct fpsimd_state fpsimd;
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__u32 magic, size;
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int err = 0;
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/* check the magic/size information */
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__get_user_error(magic, &ctx->head.magic, err);
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__get_user_error(size, &ctx->head.size, err);
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if (err)
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return -EFAULT;
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if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
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return -EINVAL;
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/* copy the FP and status/control registers */
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err = __copy_from_user(fpsimd.vregs, ctx->vregs,
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sizeof(fpsimd.vregs));
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__get_user_error(fpsimd.fpsr, &ctx->fpsr, err);
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__get_user_error(fpsimd.fpcr, &ctx->fpcr, err);
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/* load the hardware registers from the fpsimd_state structure */
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if (!err)
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fpsimd_update_current_state(&fpsimd);
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return err ? -EFAULT : 0;
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}
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static int restore_sigframe(struct pt_regs *regs,
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struct rt_sigframe __user *sf)
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{
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sigset_t set;
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int i, err;
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void *aux = sf->uc.uc_mcontext.__reserved;
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err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
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if (err == 0)
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set_current_blocked(&set);
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for (i = 0; i < 31; i++)
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__get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
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err);
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__get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
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__get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
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__get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
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/*
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* Avoid sys_rt_sigreturn() restarting.
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*/
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regs->syscallno = ~0UL;
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err |= !valid_user_regs(®s->user_regs, current);
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if (err == 0) {
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struct fpsimd_context *fpsimd_ctx =
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container_of(aux, struct fpsimd_context, head);
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err |= restore_fpsimd_context(fpsimd_ctx);
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}
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return err;
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}
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asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
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{
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struct rt_sigframe __user *frame;
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/* Always make any pending restarted system calls return -EINTR */
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current->restart_block.fn = do_no_restart_syscall;
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/*
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* Since we stacked the signal on a 128-bit boundary, then 'sp' should
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* be word aligned here.
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*/
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if (regs->sp & 15)
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goto badframe;
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frame = (struct rt_sigframe __user *)regs->sp;
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if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
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goto badframe;
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if (restore_sigframe(regs, frame))
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goto badframe;
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if (restore_altstack(&frame->uc.uc_stack))
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goto badframe;
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return regs->regs[0];
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badframe:
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if (show_unhandled_signals)
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pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
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current->comm, task_pid_nr(current), __func__,
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regs->pc, regs->sp);
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force_sig(SIGSEGV, current);
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return 0;
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}
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static int setup_sigframe(struct rt_sigframe __user *sf,
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struct pt_regs *regs, sigset_t *set)
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{
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int i, err = 0;
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void *aux = sf->uc.uc_mcontext.__reserved;
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struct _aarch64_ctx *end;
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/* set up the stack frame for unwinding */
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__put_user_error(regs->regs[29], &sf->fp, err);
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__put_user_error(regs->regs[30], &sf->lr, err);
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for (i = 0; i < 31; i++)
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__put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
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err);
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__put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err);
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__put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err);
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__put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err);
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__put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
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err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
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if (err == 0) {
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struct fpsimd_context *fpsimd_ctx =
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container_of(aux, struct fpsimd_context, head);
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err |= preserve_fpsimd_context(fpsimd_ctx);
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aux += sizeof(*fpsimd_ctx);
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}
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/* fault information, if valid */
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if (current->thread.fault_code) {
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struct esr_context *esr_ctx =
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container_of(aux, struct esr_context, head);
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__put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err);
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__put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err);
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__put_user_error(current->thread.fault_code, &esr_ctx->esr, err);
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aux += sizeof(*esr_ctx);
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}
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/* set the "end" magic */
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end = aux;
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__put_user_error(0, &end->magic, err);
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__put_user_error(0, &end->size, err);
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return err;
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}
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static struct rt_sigframe __user *get_sigframe(struct ksignal *ksig,
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struct pt_regs *regs)
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{
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unsigned long sp, sp_top;
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struct rt_sigframe __user *frame;
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sp = sp_top = sigsp(regs->sp, ksig);
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sp = (sp - sizeof(struct rt_sigframe)) & ~15;
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frame = (struct rt_sigframe __user *)sp;
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/*
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* Check that we can actually write to the signal frame.
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*/
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if (!access_ok(VERIFY_WRITE, frame, sp_top - sp))
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frame = NULL;
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return frame;
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}
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static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
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void __user *frame, int usig)
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{
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__sigrestore_t sigtramp;
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regs->regs[0] = usig;
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regs->sp = (unsigned long)frame;
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regs->regs[29] = regs->sp + offsetof(struct rt_sigframe, fp);
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regs->pc = (unsigned long)ka->sa.sa_handler;
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if (ka->sa.sa_flags & SA_RESTORER)
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sigtramp = ka->sa.sa_restorer;
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else
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sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
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regs->regs[30] = (unsigned long)sigtramp;
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}
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static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set,
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struct pt_regs *regs)
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{
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struct rt_sigframe __user *frame;
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int err = 0;
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frame = get_sigframe(ksig, regs);
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if (!frame)
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return 1;
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__put_user_error(0, &frame->uc.uc_flags, err);
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__put_user_error(NULL, &frame->uc.uc_link, err);
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err |= __save_altstack(&frame->uc.uc_stack, regs->sp);
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err |= setup_sigframe(frame, regs, set);
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if (err == 0) {
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setup_return(regs, &ksig->ka, frame, usig);
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if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
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err |= copy_siginfo_to_user(&frame->info, &ksig->info);
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regs->regs[1] = (unsigned long)&frame->info;
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regs->regs[2] = (unsigned long)&frame->uc;
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}
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}
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return err;
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}
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static void setup_restart_syscall(struct pt_regs *regs)
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{
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if (is_compat_task())
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compat_setup_restart_syscall(regs);
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else
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regs->regs[8] = __NR_restart_syscall;
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}
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/*
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* OK, we're invoking a handler
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*/
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static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
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{
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struct task_struct *tsk = current;
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sigset_t *oldset = sigmask_to_save();
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int usig = ksig->sig;
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int ret;
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/*
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* Set up the stack frame
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*/
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if (is_compat_task()) {
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if (ksig->ka.sa.sa_flags & SA_SIGINFO)
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ret = compat_setup_rt_frame(usig, ksig, oldset, regs);
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else
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ret = compat_setup_frame(usig, ksig, oldset, regs);
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} else {
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ret = setup_rt_frame(usig, ksig, oldset, regs);
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}
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/*
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* Check that the resulting registers are actually sane.
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*/
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ret |= !valid_user_regs(®s->user_regs, current);
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/*
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* Fast forward the stepping logic so we step into the signal
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* handler.
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*/
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if (!ret)
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user_fastforward_single_step(tsk);
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signal_setup_done(ret, ksig, 0);
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}
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/*
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* Note that 'init' is a special process: it doesn't get signals it doesn't
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* want to handle. Thus you cannot kill init even with a SIGKILL even by
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* mistake.
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*
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* Note that we go through the signals twice: once to check the signals that
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* the kernel can handle, and then we build all the user-level signal handling
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* stack-frames in one go after that.
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*/
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static void do_signal(struct pt_regs *regs)
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{
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unsigned long continue_addr = 0, restart_addr = 0;
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int retval = 0;
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int syscall = (int)regs->syscallno;
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struct ksignal ksig;
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/*
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* If we were from a system call, check for system call restarting...
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*/
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if (syscall >= 0) {
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continue_addr = regs->pc;
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restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4);
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retval = regs->regs[0];
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/*
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* Avoid additional syscall restarting via ret_to_user.
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*/
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regs->syscallno = ~0UL;
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/*
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* Prepare for system call restart. We do this here so that a
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* debugger will see the already changed PC.
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*/
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switch (retval) {
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case -ERESTARTNOHAND:
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case -ERESTARTSYS:
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case -ERESTARTNOINTR:
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case -ERESTART_RESTARTBLOCK:
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regs->regs[0] = regs->orig_x0;
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regs->pc = restart_addr;
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break;
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}
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}
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/*
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* Get the signal to deliver. When running under ptrace, at this point
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* the debugger may change all of our registers.
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*/
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if (get_signal(&ksig)) {
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/*
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* Depending on the signal settings, we may need to revert the
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* decision to restart the system call, but skip this if a
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* debugger has chosen to restart at a different PC.
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*/
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if (regs->pc == restart_addr &&
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(retval == -ERESTARTNOHAND ||
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retval == -ERESTART_RESTARTBLOCK ||
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(retval == -ERESTARTSYS &&
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!(ksig.ka.sa.sa_flags & SA_RESTART)))) {
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regs->regs[0] = -EINTR;
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regs->pc = continue_addr;
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}
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handle_signal(&ksig, regs);
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return;
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}
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/*
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* Handle restarting a different system call. As above, if a debugger
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* has chosen to restart at a different PC, ignore the restart.
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*/
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if (syscall >= 0 && regs->pc == restart_addr) {
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if (retval == -ERESTART_RESTARTBLOCK)
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setup_restart_syscall(regs);
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user_rewind_single_step(current);
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}
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restore_saved_sigmask();
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}
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asmlinkage void do_notify_resume(struct pt_regs *regs,
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unsigned int thread_flags)
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{
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/*
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* The assembly code enters us with IRQs off, but it hasn't
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* informed the tracing code of that for efficiency reasons.
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* Update the trace code with the current status.
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*/
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trace_hardirqs_off();
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do {
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if (thread_flags & _TIF_NEED_RESCHED) {
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schedule();
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} else {
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local_irq_enable();
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if (thread_flags & _TIF_UPROBE)
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uprobe_notify_resume(regs);
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if (thread_flags & _TIF_SIGPENDING)
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do_signal(regs);
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if (thread_flags & _TIF_NOTIFY_RESUME) {
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clear_thread_flag(TIF_NOTIFY_RESUME);
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tracehook_notify_resume(regs);
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}
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if (thread_flags & _TIF_FOREIGN_FPSTATE)
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fpsimd_restore_current_state();
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}
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local_irq_disable();
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thread_flags = READ_ONCE(current_thread_info()->flags);
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} while (thread_flags & _TIF_WORK_MASK);
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}
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