// SPDX-License-Identifier: GPL-2.0-only /* * Based on arch/arm/kernel/signal.c * * Copyright (C) 1995-2009 Russell King * Copyright (C) 2012 ARM Ltd. * Modified by Will Deacon <will.deacon@arm.com> */ #include <linux/compat.h> #include <linux/signal.h> #include <linux/syscalls.h> #include <linux/ratelimit.h> #include <asm/esr.h> #include <asm/fpsimd.h> #include <asm/signal32.h> #include <asm/traps.h> #include <linux/uaccess.h> #include <asm/unistd.h> #include <asm/vdso.h> struct compat_vfp_sigframe { compat_ulong_t magic; compat_ulong_t size; struct compat_user_vfp { compat_u64 fpregs[32]; compat_ulong_t fpscr; } ufp; struct compat_user_vfp_exc { compat_ulong_t fpexc; compat_ulong_t fpinst; compat_ulong_t fpinst2; } ufp_exc; } __attribute__((__aligned__(8))); #define VFP_MAGIC 0x56465001 #define VFP_STORAGE_SIZE sizeof(struct compat_vfp_sigframe) #define FSR_WRITE_SHIFT (11) struct compat_aux_sigframe { struct compat_vfp_sigframe vfp; /* Something that isn't a valid magic number for any coprocessor. */ unsigned long end_magic; } __attribute__((__aligned__(8))); #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP))) static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set) { compat_sigset_t cset; cset.sig[0] = set->sig[0] & 0xffffffffull; cset.sig[1] = set->sig[0] >> 32; return copy_to_user(uset, &cset, sizeof(*uset)); } static inline int get_sigset_t(sigset_t *set, const compat_sigset_t __user *uset) { compat_sigset_t s32; if (copy_from_user(&s32, uset, sizeof(*uset))) return -EFAULT; set->sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32); return 0; } /* * VFP save/restore code. * * We have to be careful with endianness, since the fpsimd context-switch * code operates on 128-bit (Q) register values whereas the compat ABI * uses an array of 64-bit (D) registers. Consequently, we need to swap * the two halves of each Q register when running on a big-endian CPU. */ union __fpsimd_vreg { __uint128_t raw; struct { #ifdef __AARCH64EB__ u64 hi; u64 lo; #else u64 lo; u64 hi; #endif }; }; static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame) { struct user_fpsimd_state const *fpsimd = ¤t->thread.uw.fpsimd_state; compat_ulong_t magic = VFP_MAGIC; compat_ulong_t size = VFP_STORAGE_SIZE; compat_ulong_t fpscr, fpexc; int i, err = 0; /* * Save the hardware registers to the fpsimd_state structure. * Note that this also saves V16-31, which aren't visible * in AArch32. */ fpsimd_signal_preserve_current_state(); /* Place structure header on the stack */ __put_user_error(magic, &frame->magic, err); __put_user_error(size, &frame->size, err); /* * Now copy the FP registers. Since the registers are packed, * we can copy the prefix we want (V0-V15) as it is. */ for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) { union __fpsimd_vreg vreg = { .raw = fpsimd->vregs[i >> 1], }; __put_user_error(vreg.lo, &frame->ufp.fpregs[i], err); __put_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err); } /* Create an AArch32 fpscr from the fpsr and the fpcr. */ fpscr = (fpsimd->fpsr & VFP_FPSCR_STAT_MASK) | (fpsimd->fpcr & VFP_FPSCR_CTRL_MASK); __put_user_error(fpscr, &frame->ufp.fpscr, err); /* * The exception register aren't available so we fake up a * basic FPEXC and zero everything else. */ fpexc = (1 << 30); __put_user_error(fpexc, &frame->ufp_exc.fpexc, err); __put_user_error(0, &frame->ufp_exc.fpinst, err); __put_user_error(0, &frame->ufp_exc.fpinst2, err); return err ? -EFAULT : 0; } static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame) { struct user_fpsimd_state fpsimd; compat_ulong_t magic = VFP_MAGIC; compat_ulong_t size = VFP_STORAGE_SIZE; compat_ulong_t fpscr; int i, err = 0; __get_user_error(magic, &frame->magic, err); __get_user_error(size, &frame->size, err); if (err) return -EFAULT; if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE) return -EINVAL; /* Copy the FP registers into the start of the fpsimd_state. */ for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) { union __fpsimd_vreg vreg; __get_user_error(vreg.lo, &frame->ufp.fpregs[i], err); __get_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err); fpsimd.vregs[i >> 1] = vreg.raw; } /* Extract the fpsr and the fpcr from the fpscr */ __get_user_error(fpscr, &frame->ufp.fpscr, err); fpsimd.fpsr = fpscr & VFP_FPSCR_STAT_MASK; fpsimd.fpcr = fpscr & VFP_FPSCR_CTRL_MASK; /* * We don't need to touch the exception register, so * reload the hardware state. */ if (!err) fpsimd_update_current_state(&fpsimd); return err ? -EFAULT : 0; } static int compat_restore_sigframe(struct pt_regs *regs, struct compat_sigframe __user *sf) { int err; sigset_t set; struct compat_aux_sigframe __user *aux; unsigned long psr; err = get_sigset_t(&set, &sf->uc.uc_sigmask); if (err == 0) { sigdelsetmask(&set, ~_BLOCKABLE); set_current_blocked(&set); } __get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err); __get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err); __get_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err); __get_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err); __get_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err); __get_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err); __get_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err); __get_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err); __get_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err); __get_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err); __get_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err); __get_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err); __get_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err); __get_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err); __get_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err); __get_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err); __get_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err); regs->pstate = compat_psr_to_pstate(psr); /* * Avoid compat_sys_sigreturn() restarting. */ forget_syscall(regs); err |= !valid_user_regs(®s->user_regs, current); aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace; if (err == 0) err |= compat_restore_vfp_context(&aux->vfp); return err; } COMPAT_SYSCALL_DEFINE0(sigreturn) { struct pt_regs *regs = current_pt_regs(); struct compat_sigframe __user *frame; /* Always make any pending restarted system calls return -EINTR */ current->restart_block.fn = do_no_restart_syscall; /* * Since we stacked the signal on a 64-bit boundary, * then 'sp' should be word aligned here. If it's * not, then the user is trying to mess with us. */ if (regs->compat_sp & 7) goto badframe; frame = (struct compat_sigframe __user *)regs->compat_sp; if (!access_ok(frame, sizeof (*frame))) goto badframe; if (compat_restore_sigframe(regs, frame)) goto badframe; return regs->regs[0]; badframe: arm64_notify_segfault(regs->compat_sp); return 0; } COMPAT_SYSCALL_DEFINE0(rt_sigreturn) { struct pt_regs *regs = current_pt_regs(); struct compat_rt_sigframe __user *frame; /* Always make any pending restarted system calls return -EINTR */ current->restart_block.fn = do_no_restart_syscall; /* * Since we stacked the signal on a 64-bit boundary, * then 'sp' should be word aligned here. If it's * not, then the user is trying to mess with us. */ if (regs->compat_sp & 7) goto badframe; frame = (struct compat_rt_sigframe __user *)regs->compat_sp; if (!access_ok(frame, sizeof (*frame))) goto badframe; if (compat_restore_sigframe(regs, &frame->sig)) goto badframe; if (compat_restore_altstack(&frame->sig.uc.uc_stack)) goto badframe; return regs->regs[0]; badframe: arm64_notify_segfault(regs->compat_sp); return 0; } static void __user *compat_get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize) { compat_ulong_t sp = sigsp(regs->compat_sp, ksig); void __user *frame; /* * ATPCS B01 mandates 8-byte alignment */ frame = compat_ptr((compat_uptr_t)((sp - framesize) & ~7)); /* * Check that we can actually write to the signal frame. */ if (!access_ok(frame, framesize)) frame = NULL; return frame; } static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka, compat_ulong_t __user *rc, void __user *frame, int usig) { compat_ulong_t handler = ptr_to_compat(ka->sa.sa_handler); compat_ulong_t retcode; compat_ulong_t spsr = regs->pstate & ~(PSR_f | PSR_AA32_E_BIT); int thumb; /* Check if the handler is written for ARM or Thumb */ thumb = handler & 1; if (thumb) spsr |= PSR_AA32_T_BIT; else spsr &= ~PSR_AA32_T_BIT; /* The IT state must be cleared for both ARM and Thumb-2 */ spsr &= ~PSR_AA32_IT_MASK; /* Restore the original endianness */ spsr |= PSR_AA32_ENDSTATE; if (ka->sa.sa_flags & SA_RESTORER) { retcode = ptr_to_compat(ka->sa.sa_restorer); } else { /* Set up sigreturn pointer */ #ifdef CONFIG_COMPAT_VDSO void *vdso_base = current->mm->context.vdso; void *vdso_trampoline; if (ka->sa.sa_flags & SA_SIGINFO) { if (thumb) { vdso_trampoline = VDSO_SYMBOL(vdso_base, compat_rt_sigreturn_thumb); } else { vdso_trampoline = VDSO_SYMBOL(vdso_base, compat_rt_sigreturn_arm); } } else { if (thumb) { vdso_trampoline = VDSO_SYMBOL(vdso_base, compat_sigreturn_thumb); } else { vdso_trampoline = VDSO_SYMBOL(vdso_base, compat_sigreturn_arm); } } retcode = ptr_to_compat(vdso_trampoline) + thumb; #else unsigned int idx = thumb << 1; if (ka->sa.sa_flags & SA_SIGINFO) idx += 3; retcode = (unsigned long)current->mm->context.vdso + (idx << 2) + thumb; #endif } regs->regs[0] = usig; regs->compat_sp = ptr_to_compat(frame); regs->compat_lr = retcode; regs->pc = handler; regs->pstate = spsr; } static int compat_setup_sigframe(struct compat_sigframe __user *sf, struct pt_regs *regs, sigset_t *set) { struct compat_aux_sigframe __user *aux; unsigned long psr = pstate_to_compat_psr(regs->pstate); int err = 0; __put_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err); __put_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err); __put_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err); __put_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err); __put_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err); __put_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err); __put_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err); __put_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err); __put_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err); __put_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err); __put_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err); __put_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err); __put_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err); __put_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err); __put_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err); __put_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err); __put_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err); __put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.trap_no, err); /* set the compat FSR WnR */ __put_user_error(!!(current->thread.fault_code & ESR_ELx_WNR) << FSR_WRITE_SHIFT, &sf->uc.uc_mcontext.error_code, err); __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err); __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err); err |= put_sigset_t(&sf->uc.uc_sigmask, set); aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace; if (err == 0) err |= compat_preserve_vfp_context(&aux->vfp); __put_user_error(0, &aux->end_magic, err); return err; } /* * 32-bit signal handling routines called from signal.c */ int compat_setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct compat_rt_sigframe __user *frame; int err = 0; frame = compat_get_sigframe(ksig, regs, sizeof(*frame)); if (!frame) return 1; err |= copy_siginfo_to_user32(&frame->info, &ksig->info); __put_user_error(0, &frame->sig.uc.uc_flags, err); __put_user_error(0, &frame->sig.uc.uc_link, err); err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp); err |= compat_setup_sigframe(&frame->sig, regs, set); if (err == 0) { compat_setup_return(regs, &ksig->ka, frame->sig.retcode, frame, usig); regs->regs[1] = (compat_ulong_t)(unsigned long)&frame->info; regs->regs[2] = (compat_ulong_t)(unsigned long)&frame->sig.uc; } return err; } int compat_setup_frame(int usig, struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) { struct compat_sigframe __user *frame; int err = 0; frame = compat_get_sigframe(ksig, regs, sizeof(*frame)); if (!frame) return 1; __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err); err |= compat_setup_sigframe(frame, regs, set); if (err == 0) compat_setup_return(regs, &ksig->ka, frame->retcode, frame, usig); return err; } void compat_setup_restart_syscall(struct pt_regs *regs) { regs->regs[7] = __NR_compat_restart_syscall; }