// SPDX-License-Identifier: GPL-2.0 /* * PA-RISC architecture-specific signal handling support. * * Copyright (C) 2000 David Huggins-Daines * Copyright (C) 2000 Linuxcare, Inc. * Copyright (C) 2000-2022 Helge Deller * Copyright (C) 2022 John David Anglin * * Based on the ia64, i386, and alpha versions. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_COMPAT #include "signal32.h" #endif #define DEBUG_SIG 0 #define DEBUG_SIG_LEVEL 2 #if DEBUG_SIG #define DBG(LEVEL, ...) \ ((DEBUG_SIG_LEVEL >= LEVEL) \ ? printk(__VA_ARGS__) : (void) 0) #else #define DBG(LEVEL, ...) #endif /* gcc will complain if a pointer is cast to an integer of different * size. If you really need to do this (and we do for an ELF32 user * application in an ELF64 kernel) then you have to do a cast to an * integer of the same size first. The A() macro accomplishes * this. */ #define A(__x) ((unsigned long)(__x)) /* * Do a signal return - restore sigcontext. */ static long restore_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs) { long err = 0; err |= __copy_from_user(regs->gr, sc->sc_gr, sizeof(regs->gr)); err |= __copy_from_user(regs->fr, sc->sc_fr, sizeof(regs->fr)); err |= __copy_from_user(regs->iaoq, sc->sc_iaoq, sizeof(regs->iaoq)); err |= __copy_from_user(regs->iasq, sc->sc_iasq, sizeof(regs->iasq)); err |= __get_user(regs->sar, &sc->sc_sar); DBG(2, "%s: iaoq is %#lx / %#lx\n", __func__, regs->iaoq[0], regs->iaoq[1]); DBG(2, "%s: r28 is %ld\n", __func__, regs->gr[28]); return err; } asmlinkage void sys_rt_sigreturn(struct pt_regs *regs, int in_syscall) { struct rt_sigframe __user *frame; sigset_t set; unsigned long usp = (regs->gr[30] & ~(0x01UL)); unsigned long sigframe_size = PARISC_RT_SIGFRAME_SIZE; #ifdef CONFIG_64BIT struct compat_rt_sigframe __user * compat_frame; if (is_compat_task()) sigframe_size = PARISC_RT_SIGFRAME_SIZE32; #endif current->restart_block.fn = do_no_restart_syscall; /* Unwind the user stack to get the rt_sigframe structure. */ frame = (struct rt_sigframe __user *) (usp - sigframe_size); DBG(2, "%s: frame is %p pid %d\n", __func__, frame, task_pid_nr(current)); regs->orig_r28 = 1; /* no restarts for sigreturn */ #ifdef CONFIG_64BIT compat_frame = (struct compat_rt_sigframe __user *)frame; if (is_compat_task()) { if (get_compat_sigset(&set, &compat_frame->uc.uc_sigmask)) goto give_sigsegv; } else #endif { if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) goto give_sigsegv; } set_current_blocked(&set); /* Good thing we saved the old gr[30], eh? */ #ifdef CONFIG_64BIT if (is_compat_task()) { DBG(1, "%s: compat_frame->uc.uc_mcontext 0x%p\n", __func__, &compat_frame->uc.uc_mcontext); // FIXME: Load upper half from register file if (restore_sigcontext32(&compat_frame->uc.uc_mcontext, &compat_frame->regs, regs)) goto give_sigsegv; DBG(1, "%s: usp %#08lx stack 0x%p\n", __func__, usp, &compat_frame->uc.uc_stack); if (compat_restore_altstack(&compat_frame->uc.uc_stack)) goto give_sigsegv; } else #endif { DBG(1, "%s: frame->uc.uc_mcontext 0x%p\n", __func__, &frame->uc.uc_mcontext); if (restore_sigcontext(&frame->uc.uc_mcontext, regs)) goto give_sigsegv; DBG(1, "%s: usp %#08lx stack 0x%p\n", __func__, usp, &frame->uc.uc_stack); if (restore_altstack(&frame->uc.uc_stack)) goto give_sigsegv; } /* If we are on the syscall path IAOQ will not be restored, and * if we are on the interrupt path we must not corrupt gr31. */ if (in_syscall) regs->gr[31] = regs->iaoq[0]; return; give_sigsegv: DBG(1, "%s: Sending SIGSEGV\n", __func__); force_sig(SIGSEGV); return; } /* * Set up a signal frame. */ static inline void __user * get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size) { /*FIXME: ELF32 vs. ELF64 has different frame_size, but since we don't use the parameter it doesn't matter */ DBG(1, "%s: ka = %#lx, sp = %#lx, frame_size = %zu\n", __func__, (unsigned long)ka, sp, frame_size); /* Align alternate stack and reserve 64 bytes for the signal handler's frame marker. */ if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp)) sp = (current->sas_ss_sp + 0x7f) & ~0x3f; /* Stacks grow up! */ DBG(1, "%s: Returning sp = %#lx\n", __func__, (unsigned long)sp); return (void __user *) sp; /* Stacks grow up. Fun. */ } static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, long in_syscall) { unsigned long flags = 0; long err = 0; if (on_sig_stack((unsigned long) sc)) flags |= PARISC_SC_FLAG_ONSTACK; if (in_syscall) { flags |= PARISC_SC_FLAG_IN_SYSCALL; /* regs->iaoq is undefined in the syscall return path */ err |= __put_user(regs->gr[31], &sc->sc_iaoq[0]); err |= __put_user(regs->gr[31]+4, &sc->sc_iaoq[1]); err |= __put_user(regs->sr[3], &sc->sc_iasq[0]); err |= __put_user(regs->sr[3], &sc->sc_iasq[1]); DBG(1, "%s: iaoq %#lx / %#lx (in syscall)\n", __func__, regs->gr[31], regs->gr[31]+4); } else { err |= __copy_to_user(sc->sc_iaoq, regs->iaoq, sizeof(regs->iaoq)); err |= __copy_to_user(sc->sc_iasq, regs->iasq, sizeof(regs->iasq)); DBG(1, "%s: iaoq %#lx / %#lx (not in syscall)\n", __func__, regs->iaoq[0], regs->iaoq[1]); } err |= __put_user(flags, &sc->sc_flags); err |= __copy_to_user(sc->sc_gr, regs->gr, sizeof(regs->gr)); err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr)); err |= __put_user(regs->sar, &sc->sc_sar); DBG(1, "%s: r28 is %ld\n", __func__, regs->gr[28]); return err; } static long setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs, long in_syscall) { struct rt_sigframe __user *frame; unsigned long rp, usp; unsigned long haddr, sigframe_size; unsigned long start; int err = 0; #ifdef CONFIG_64BIT struct compat_rt_sigframe __user * compat_frame; #endif usp = (regs->gr[30] & ~(0x01UL)); sigframe_size = PARISC_RT_SIGFRAME_SIZE; #ifdef CONFIG_64BIT if (is_compat_task()) { /* The gcc alloca implementation leaves garbage in the upper 32 bits of sp */ usp = (compat_uint_t)usp; sigframe_size = PARISC_RT_SIGFRAME_SIZE32; } #endif frame = get_sigframe(&ksig->ka, usp, sigframe_size); DBG(1, "%s: frame %p info %p\n", __func__, frame, &ksig->info); start = (unsigned long) frame; if (start >= TASK_SIZE_MAX - sigframe_size) return -EFAULT; #ifdef CONFIG_64BIT compat_frame = (struct compat_rt_sigframe __user *)frame; if (is_compat_task()) { DBG(1, "%s: frame->info = 0x%p\n", __func__, &compat_frame->info); err |= copy_siginfo_to_user32(&compat_frame->info, &ksig->info); err |= __compat_save_altstack( &compat_frame->uc.uc_stack, regs->gr[30]); DBG(1, "%s: frame->uc = 0x%p\n", __func__, &compat_frame->uc); DBG(1, "%s: frame->uc.uc_mcontext = 0x%p\n", __func__, &compat_frame->uc.uc_mcontext); err |= setup_sigcontext32(&compat_frame->uc.uc_mcontext, &compat_frame->regs, regs, in_syscall); err |= put_compat_sigset(&compat_frame->uc.uc_sigmask, set, sizeof(compat_sigset_t)); } else #endif { DBG(1, "%s: frame->info = 0x%p\n", __func__, &frame->info); err |= copy_siginfo_to_user(&frame->info, &ksig->info); err |= __save_altstack(&frame->uc.uc_stack, regs->gr[30]); DBG(1, "%s: frame->uc = 0x%p\n", __func__, &frame->uc); DBG(1, "%s: frame->uc.uc_mcontext = 0x%p\n", __func__, &frame->uc.uc_mcontext); err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, in_syscall); /* FIXME: Should probably be converted as well for the compat case */ err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); } if (err) return -EFAULT; #ifdef CONFIG_64BIT if (!is_compat_task()) rp = VDSO64_SYMBOL(current, sigtramp_rt); else #endif rp = VDSO32_SYMBOL(current, sigtramp_rt); if (in_syscall) rp += 4*4; /* skip 4 instructions and start at ldi 1,%r25 */ haddr = A(ksig->ka.sa.sa_handler); /* The sa_handler may be a pointer to a function descriptor */ #ifdef CONFIG_64BIT if (is_compat_task()) { #endif if (haddr & PA_PLABEL_FDESC) { Elf32_Fdesc fdesc; Elf32_Fdesc __user *ufdesc = (Elf32_Fdesc __user *)A(haddr & ~3); err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc)); if (err) return -EFAULT; haddr = fdesc.addr; regs->gr[19] = fdesc.gp; } #ifdef CONFIG_64BIT } else { Elf64_Fdesc fdesc; Elf64_Fdesc __user *ufdesc = (Elf64_Fdesc __user *)A(haddr & ~3); err = __copy_from_user(&fdesc, ufdesc, sizeof(fdesc)); if (err) return -EFAULT; haddr = fdesc.addr; regs->gr[19] = fdesc.gp; DBG(1, "%s: 64 bit signal, exe=%#lx, r19=%#lx, in_syscall=%d\n", __func__, haddr, regs->gr[19], in_syscall); } #endif /* The syscall return path will create IAOQ values from r31. */ if (in_syscall) { regs->gr[31] = haddr; #ifdef CONFIG_64BIT if (!test_thread_flag(TIF_32BIT)) sigframe_size |= 1; /* XXX ???? */ #endif } else { unsigned long psw = USER_PSW; #ifdef CONFIG_64BIT if (!test_thread_flag(TIF_32BIT)) psw |= PSW_W; #endif /* If we are singlestepping, arrange a trap to be delivered when we return to userspace. Note the semantics -- we should trap before the first insn in the handler is executed. Ref: http://sources.redhat.com/ml/gdb/2004-11/msg00245.html */ if (pa_psw(current)->r) { pa_psw(current)->r = 0; psw |= PSW_R; mtctl(-1, 0); } regs->gr[0] = psw; regs->iaoq[0] = haddr | PRIV_USER; regs->iaoq[1] = regs->iaoq[0] + 4; } regs->gr[2] = rp; /* userland return pointer */ regs->gr[26] = ksig->sig; /* signal number */ #ifdef CONFIG_64BIT if (is_compat_task()) { regs->gr[25] = A(&compat_frame->info); /* siginfo pointer */ regs->gr[24] = A(&compat_frame->uc); /* ucontext pointer */ } else #endif { regs->gr[25] = A(&frame->info); /* siginfo pointer */ regs->gr[24] = A(&frame->uc); /* ucontext pointer */ } DBG(1, "%s: making sigreturn frame: %#lx + %#lx = %#lx\n", __func__, regs->gr[30], sigframe_size, regs->gr[30] + sigframe_size); /* Raise the user stack pointer to make a proper call frame. */ regs->gr[30] = (A(frame) + sigframe_size); DBG(1, "%s: sig deliver (%s,%d) frame=0x%p sp=%#lx iaoq=%#lx/%#lx rp=%#lx\n", __func__, current->comm, current->pid, frame, regs->gr[30], regs->iaoq[0], regs->iaoq[1], rp); return 0; } /* * OK, we're invoking a handler. */ static void handle_signal(struct ksignal *ksig, struct pt_regs *regs, long in_syscall) { int ret; sigset_t *oldset = sigmask_to_save(); DBG(1, "%s: sig=%d, ka=%p, info=%p, oldset=%p, regs=%p\n", __func__, ksig->sig, &ksig->ka, &ksig->info, oldset, regs); /* Set up the stack frame */ ret = setup_rt_frame(ksig, oldset, regs, in_syscall); signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP) || test_thread_flag(TIF_BLOCKSTEP)); DBG(1, "%s: Exit (success), regs->gr[28] = %ld\n", __func__, regs->gr[28]); } /* * Check how the syscall number gets loaded into %r20 within * the delay branch in userspace and adjust as needed. */ static void check_syscallno_in_delay_branch(struct pt_regs *regs) { u32 opcode, source_reg; u32 __user *uaddr; int err; /* Usually we don't have to restore %r20 (the system call number) * because it gets loaded in the delay slot of the branch external * instruction via the ldi instruction. * In some cases a register-to-register copy instruction might have * been used instead, in which case we need to copy the syscall * number into the source register before returning to userspace. */ /* A syscall is just a branch, so all we have to do is fiddle the * return pointer so that the ble instruction gets executed again. */ regs->gr[31] -= 8; /* delayed branching */ /* Get assembler opcode of code in delay branch */ uaddr = (u32 __user *) ((regs->gr[31] & ~3) + 4); err = get_user(opcode, uaddr); if (err) return; /* Check if delay branch uses "ldi int,%r20" */ if ((opcode & 0xffff0000) == 0x34140000) return; /* everything ok, just return */ /* Check if delay branch uses "nop" */ if (opcode == INSN_NOP) return; /* Check if delay branch uses "copy %rX,%r20" */ if ((opcode & 0xffe0ffff) == 0x08000254) { source_reg = (opcode >> 16) & 31; regs->gr[source_reg] = regs->gr[20]; return; } pr_warn("syscall restart: %s (pid %d): unexpected opcode 0x%08x\n", current->comm, task_pid_nr(current), opcode); } static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka) { if (regs->orig_r28) return; regs->orig_r28 = 1; /* no more restarts */ DBG(1, "%s: orig_r28 = %ld pid %d r20 %ld\n", __func__, regs->orig_r28, task_pid_nr(current), regs->gr[20]); /* Check the return code */ switch (regs->gr[28]) { case -ERESTART_RESTARTBLOCK: case -ERESTARTNOHAND: DBG(1, "%s: ERESTARTNOHAND: returning -EINTR\n", __func__); regs->gr[28] = -EINTR; break; case -ERESTARTSYS: if (!(ka->sa.sa_flags & SA_RESTART)) { DBG(1, "%s: ERESTARTSYS: putting -EINTR pid %d\n", __func__, task_pid_nr(current)); regs->gr[28] = -EINTR; break; } fallthrough; case -ERESTARTNOINTR: DBG(1, "%s: %ld\n", __func__, regs->gr[28]); check_syscallno_in_delay_branch(regs); break; } } static inline void insert_restart_trampoline(struct pt_regs *regs) { if (regs->orig_r28) return; regs->orig_r28 = 1; /* no more restarts */ DBG(2, "%s: gr28 = %ld pid %d\n", __func__, regs->gr[28], task_pid_nr(current)); switch (regs->gr[28]) { case -ERESTART_RESTARTBLOCK: { /* Restart the system call - no handlers present */ unsigned int *usp = (unsigned int *)regs->gr[30]; unsigned long rp; long err = 0; /* check that we don't exceed the stack */ if (A(&usp[0]) >= TASK_SIZE_MAX - 5 * sizeof(int)) return; /* Call trampoline in vdso to restart the syscall * with __NR_restart_syscall. * Original return addresses are on stack like this: * * 0: * 4: <2nd half for 64-bit> */ #ifdef CONFIG_64BIT if (!is_compat_task()) { err |= put_user(regs->gr[31] >> 32, &usp[0]); err |= put_user(regs->gr[31] & 0xffffffff, &usp[1]); rp = VDSO64_SYMBOL(current, restart_syscall); } else #endif { err |= put_user(regs->gr[31], &usp[0]); rp = VDSO32_SYMBOL(current, restart_syscall); } WARN_ON(err); regs->gr[31] = rp; DBG(1, "%s: ERESTART_RESTARTBLOCK\n", __func__); return; } case -EINTR: /* ok, was handled before and should be returned. */ break; case -ERESTARTNOHAND: case -ERESTARTSYS: case -ERESTARTNOINTR: DBG(1, "%s: Type %ld\n", __func__, regs->gr[28]); check_syscallno_in_delay_branch(regs); return; default: break; } } /* * We need to be able to restore the syscall arguments (r21-r26) to * restart syscalls. Thus, the syscall path should save them in the * pt_regs structure (it's okay to do so since they are caller-save * registers). As noted below, the syscall number gets restored for * us due to the magic of delayed branching. */ static void do_signal(struct pt_regs *regs, long in_syscall) { struct ksignal ksig; int restart_syscall; bool has_handler; has_handler = get_signal(&ksig); restart_syscall = 0; if (in_syscall) restart_syscall = 1; if (has_handler) { /* Restart a system call if necessary. */ if (restart_syscall) syscall_restart(regs, &ksig.ka); handle_signal(&ksig, regs, in_syscall); DBG(1, "%s: Handled signal pid %d\n", __func__, task_pid_nr(current)); return; } /* Do we need to restart the system call? */ if (restart_syscall) insert_restart_trampoline(regs); DBG(1, "%s: Exit (not delivered), regs->gr[28] = %ld orig_r28 = %ld pid %d\n", __func__, regs->gr[28], regs->orig_r28, task_pid_nr(current)); restore_saved_sigmask(); } asmlinkage void do_notify_resume(struct pt_regs *regs, long in_syscall) { if (test_thread_flag(TIF_SIGPENDING) || test_thread_flag(TIF_NOTIFY_SIGNAL)) do_signal(regs, in_syscall); if (test_thread_flag(TIF_NOTIFY_RESUME)) resume_user_mode_work(regs); }