diff options
Diffstat (limited to 'arch/parisc/kernel/signal.c')
| -rw-r--r-- | arch/parisc/kernel/signal.c | 589 |
1 files changed, 589 insertions, 0 deletions
diff --git a/arch/parisc/kernel/signal.c b/arch/parisc/kernel/signal.c new file mode 100644 index 000000000..8bc0ddaa6 --- /dev/null +++ b/arch/parisc/kernel/signal.c @@ -0,0 +1,589 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * PA-RISC architecture-specific signal handling support. + * + * Copyright (C) 2000 David Huggins-Daines <dhd@debian.org> + * Copyright (C) 2000 Linuxcare, Inc. + * Copyright (C) 2000-2022 Helge Deller <deller@gmx.de> + * Copyright (C) 2022 John David Anglin <dave.anglin@bell.net> + * + * Based on the ia64, i386, and alpha versions. + */ + +#include <linux/sched.h> +#include <linux/sched/debug.h> +#include <linux/mm.h> +#include <linux/smp.h> +#include <linux/kernel.h> +#include <linux/signal.h> +#include <linux/errno.h> +#include <linux/wait.h> +#include <linux/ptrace.h> +#include <linux/resume_user_mode.h> +#include <linux/unistd.h> +#include <linux/stddef.h> +#include <linux/compat.h> +#include <linux/elf.h> +#include <asm/ucontext.h> +#include <asm/rt_sigframe.h> +#include <linux/uaccess.h> +#include <asm/cacheflush.h> +#include <asm/asm-offsets.h> +#include <asm/vdso.h> + +#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; +} + +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, int 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, + int 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, int 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 = (unsigned int *) ((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: <return address (orig r31)> + * 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(); +} + +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); +} |