diff options
Diffstat (limited to 'arch/arm64/kernel/signal.c')
| -rw-r--r-- | arch/arm64/kernel/signal.c | 974 |
1 files changed, 974 insertions, 0 deletions
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c new file mode 100644 index 000000000..ca565853d --- /dev/null +++ b/arch/arm64/kernel/signal.c @@ -0,0 +1,974 @@ +/* + * Based on arch/arm/kernel/signal.c + * + * Copyright (C) 1995-2009 Russell King + * Copyright (C) 2012 ARM Ltd. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <linux/cache.h> +#include <linux/compat.h> +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/signal.h> +#include <linux/personality.h> +#include <linux/freezer.h> +#include <linux/stddef.h> +#include <linux/uaccess.h> +#include <linux/sizes.h> +#include <linux/string.h> +#include <linux/tracehook.h> +#include <linux/ratelimit.h> +#include <linux/syscalls.h> + +#include <asm/daifflags.h> +#include <asm/debug-monitors.h> +#include <asm/elf.h> +#include <asm/cacheflush.h> +#include <asm/ucontext.h> +#include <asm/unistd.h> +#include <asm/fpsimd.h> +#include <asm/ptrace.h> +#include <asm/signal32.h> +#include <asm/traps.h> +#include <asm/vdso.h> + +/* + * Do a signal return; undo the signal stack. These are aligned to 128-bit. + */ +struct rt_sigframe { + struct siginfo info; + struct ucontext uc; +}; + +struct frame_record { + u64 fp; + u64 lr; +}; + +struct rt_sigframe_user_layout { + struct rt_sigframe __user *sigframe; + struct frame_record __user *next_frame; + + unsigned long size; /* size of allocated sigframe data */ + unsigned long limit; /* largest allowed size */ + + unsigned long fpsimd_offset; + unsigned long esr_offset; + unsigned long sve_offset; + unsigned long extra_offset; + unsigned long end_offset; +}; + +#define BASE_SIGFRAME_SIZE round_up(sizeof(struct rt_sigframe), 16) +#define TERMINATOR_SIZE round_up(sizeof(struct _aarch64_ctx), 16) +#define EXTRA_CONTEXT_SIZE round_up(sizeof(struct extra_context), 16) + +static void init_user_layout(struct rt_sigframe_user_layout *user) +{ + const size_t reserved_size = + sizeof(user->sigframe->uc.uc_mcontext.__reserved); + + memset(user, 0, sizeof(*user)); + user->size = offsetof(struct rt_sigframe, uc.uc_mcontext.__reserved); + + user->limit = user->size + reserved_size; + + user->limit -= TERMINATOR_SIZE; + user->limit -= EXTRA_CONTEXT_SIZE; + /* Reserve space for extension and terminator ^ */ +} + +static size_t sigframe_size(struct rt_sigframe_user_layout const *user) +{ + return round_up(max(user->size, sizeof(struct rt_sigframe)), 16); +} + +/* + * Sanity limit on the approximate maximum size of signal frame we'll + * try to generate. Stack alignment padding and the frame record are + * not taken into account. This limit is not a guarantee and is + * NOT ABI. + */ +#define SIGFRAME_MAXSZ SZ_64K + +static int __sigframe_alloc(struct rt_sigframe_user_layout *user, + unsigned long *offset, size_t size, bool extend) +{ + size_t padded_size = round_up(size, 16); + + if (padded_size > user->limit - user->size && + !user->extra_offset && + extend) { + int ret; + + user->limit += EXTRA_CONTEXT_SIZE; + ret = __sigframe_alloc(user, &user->extra_offset, + sizeof(struct extra_context), false); + if (ret) { + user->limit -= EXTRA_CONTEXT_SIZE; + return ret; + } + + /* Reserve space for the __reserved[] terminator */ + user->size += TERMINATOR_SIZE; + + /* + * Allow expansion up to SIGFRAME_MAXSZ, ensuring space for + * the terminator: + */ + user->limit = SIGFRAME_MAXSZ - TERMINATOR_SIZE; + } + + /* Still not enough space? Bad luck! */ + if (padded_size > user->limit - user->size) + return -ENOMEM; + + *offset = user->size; + user->size += padded_size; + + return 0; +} + +/* + * Allocate space for an optional record of <size> bytes in the user + * signal frame. The offset from the signal frame base address to the + * allocated block is assigned to *offset. + */ +static int sigframe_alloc(struct rt_sigframe_user_layout *user, + unsigned long *offset, size_t size) +{ + return __sigframe_alloc(user, offset, size, true); +} + +/* Allocate the null terminator record and prevent further allocations */ +static int sigframe_alloc_end(struct rt_sigframe_user_layout *user) +{ + int ret; + + /* Un-reserve the space reserved for the terminator: */ + user->limit += TERMINATOR_SIZE; + + ret = sigframe_alloc(user, &user->end_offset, + sizeof(struct _aarch64_ctx)); + if (ret) + return ret; + + /* Prevent further allocation: */ + user->limit = user->size; + return 0; +} + +static void __user *apply_user_offset( + struct rt_sigframe_user_layout const *user, unsigned long offset) +{ + char __user *base = (char __user *)user->sigframe; + + return base + offset; +} + +static int preserve_fpsimd_context(struct fpsimd_context __user *ctx) +{ + struct user_fpsimd_state const *fpsimd = + ¤t->thread.uw.fpsimd_state; + int err; + + /* copy the FP and status/control registers */ + err = __copy_to_user(ctx->vregs, fpsimd->vregs, sizeof(fpsimd->vregs)); + __put_user_error(fpsimd->fpsr, &ctx->fpsr, err); + __put_user_error(fpsimd->fpcr, &ctx->fpcr, err); + + /* copy the magic/size information */ + __put_user_error(FPSIMD_MAGIC, &ctx->head.magic, err); + __put_user_error(sizeof(struct fpsimd_context), &ctx->head.size, err); + + return err ? -EFAULT : 0; +} + +static int restore_fpsimd_context(struct fpsimd_context __user *ctx) +{ + struct user_fpsimd_state fpsimd; + __u32 magic, size; + int err = 0; + + /* check the magic/size information */ + __get_user_error(magic, &ctx->head.magic, err); + __get_user_error(size, &ctx->head.size, err); + if (err) + return -EFAULT; + if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context)) + return -EINVAL; + + /* copy the FP and status/control registers */ + err = __copy_from_user(fpsimd.vregs, ctx->vregs, + sizeof(fpsimd.vregs)); + __get_user_error(fpsimd.fpsr, &ctx->fpsr, err); + __get_user_error(fpsimd.fpcr, &ctx->fpcr, err); + + clear_thread_flag(TIF_SVE); + + /* load the hardware registers from the fpsimd_state structure */ + if (!err) + fpsimd_update_current_state(&fpsimd); + + return err ? -EFAULT : 0; +} + + +struct user_ctxs { + struct fpsimd_context __user *fpsimd; + struct sve_context __user *sve; +}; + +#ifdef CONFIG_ARM64_SVE + +static int preserve_sve_context(struct sve_context __user *ctx) +{ + int err = 0; + u16 reserved[ARRAY_SIZE(ctx->__reserved)]; + unsigned int vl = current->thread.sve_vl; + unsigned int vq = 0; + + if (test_thread_flag(TIF_SVE)) + vq = sve_vq_from_vl(vl); + + memset(reserved, 0, sizeof(reserved)); + + __put_user_error(SVE_MAGIC, &ctx->head.magic, err); + __put_user_error(round_up(SVE_SIG_CONTEXT_SIZE(vq), 16), + &ctx->head.size, err); + __put_user_error(vl, &ctx->vl, err); + BUILD_BUG_ON(sizeof(ctx->__reserved) != sizeof(reserved)); + err |= __copy_to_user(&ctx->__reserved, reserved, sizeof(reserved)); + + if (vq) { + /* + * This assumes that the SVE state has already been saved to + * the task struct by calling preserve_fpsimd_context(). + */ + err |= __copy_to_user((char __user *)ctx + SVE_SIG_REGS_OFFSET, + current->thread.sve_state, + SVE_SIG_REGS_SIZE(vq)); + } + + return err ? -EFAULT : 0; +} + +static int restore_sve_fpsimd_context(struct user_ctxs *user) +{ + int err; + unsigned int vq; + struct user_fpsimd_state fpsimd; + struct sve_context sve; + + if (__copy_from_user(&sve, user->sve, sizeof(sve))) + return -EFAULT; + + if (sve.vl != current->thread.sve_vl) + return -EINVAL; + + if (sve.head.size <= sizeof(*user->sve)) { + clear_thread_flag(TIF_SVE); + goto fpsimd_only; + } + + vq = sve_vq_from_vl(sve.vl); + + if (sve.head.size < SVE_SIG_CONTEXT_SIZE(vq)) + return -EINVAL; + + /* + * Careful: we are about __copy_from_user() directly into + * thread.sve_state with preemption enabled, so protection is + * needed to prevent a racing context switch from writing stale + * registers back over the new data. + */ + + fpsimd_flush_task_state(current); + barrier(); + /* From now, fpsimd_thread_switch() won't clear TIF_FOREIGN_FPSTATE */ + + set_thread_flag(TIF_FOREIGN_FPSTATE); + barrier(); + /* From now, fpsimd_thread_switch() won't touch thread.sve_state */ + + sve_alloc(current); + err = __copy_from_user(current->thread.sve_state, + (char __user const *)user->sve + + SVE_SIG_REGS_OFFSET, + SVE_SIG_REGS_SIZE(vq)); + if (err) + return -EFAULT; + + set_thread_flag(TIF_SVE); + +fpsimd_only: + /* copy the FP and status/control registers */ + /* restore_sigframe() already checked that user->fpsimd != NULL. */ + err = __copy_from_user(fpsimd.vregs, user->fpsimd->vregs, + sizeof(fpsimd.vregs)); + __get_user_error(fpsimd.fpsr, &user->fpsimd->fpsr, err); + __get_user_error(fpsimd.fpcr, &user->fpsimd->fpcr, err); + + /* load the hardware registers from the fpsimd_state structure */ + if (!err) + fpsimd_update_current_state(&fpsimd); + + return err ? -EFAULT : 0; +} + +#else /* ! CONFIG_ARM64_SVE */ + +/* Turn any non-optimised out attempts to use these into a link error: */ +extern int preserve_sve_context(void __user *ctx); +extern int restore_sve_fpsimd_context(struct user_ctxs *user); + +#endif /* ! CONFIG_ARM64_SVE */ + + +static int parse_user_sigframe(struct user_ctxs *user, + struct rt_sigframe __user *sf) +{ + struct sigcontext __user *const sc = &sf->uc.uc_mcontext; + struct _aarch64_ctx __user *head; + char __user *base = (char __user *)&sc->__reserved; + size_t offset = 0; + size_t limit = sizeof(sc->__reserved); + bool have_extra_context = false; + char const __user *const sfp = (char const __user *)sf; + + user->fpsimd = NULL; + user->sve = NULL; + + if (!IS_ALIGNED((unsigned long)base, 16)) + goto invalid; + + while (1) { + int err = 0; + u32 magic, size; + char const __user *userp; + struct extra_context const __user *extra; + u64 extra_datap; + u32 extra_size; + struct _aarch64_ctx const __user *end; + u32 end_magic, end_size; + + if (limit - offset < sizeof(*head)) + goto invalid; + + if (!IS_ALIGNED(offset, 16)) + goto invalid; + + head = (struct _aarch64_ctx __user *)(base + offset); + __get_user_error(magic, &head->magic, err); + __get_user_error(size, &head->size, err); + if (err) + return err; + + if (limit - offset < size) + goto invalid; + + switch (magic) { + case 0: + if (size) + goto invalid; + + goto done; + + case FPSIMD_MAGIC: + if (user->fpsimd) + goto invalid; + + if (size < sizeof(*user->fpsimd)) + goto invalid; + + user->fpsimd = (struct fpsimd_context __user *)head; + break; + + case ESR_MAGIC: + /* ignore */ + break; + + case SVE_MAGIC: + if (!system_supports_sve()) + goto invalid; + + if (user->sve) + goto invalid; + + if (size < sizeof(*user->sve)) + goto invalid; + + user->sve = (struct sve_context __user *)head; + break; + + case EXTRA_MAGIC: + if (have_extra_context) + goto invalid; + + if (size < sizeof(*extra)) + goto invalid; + + userp = (char const __user *)head; + + extra = (struct extra_context const __user *)userp; + userp += size; + + __get_user_error(extra_datap, &extra->datap, err); + __get_user_error(extra_size, &extra->size, err); + if (err) + return err; + + /* Check for the dummy terminator in __reserved[]: */ + + if (limit - offset - size < TERMINATOR_SIZE) + goto invalid; + + end = (struct _aarch64_ctx const __user *)userp; + userp += TERMINATOR_SIZE; + + __get_user_error(end_magic, &end->magic, err); + __get_user_error(end_size, &end->size, err); + if (err) + return err; + + if (end_magic || end_size) + goto invalid; + + /* Prevent looping/repeated parsing of extra_context */ + have_extra_context = true; + + base = (__force void __user *)extra_datap; + if (!IS_ALIGNED((unsigned long)base, 16)) + goto invalid; + + if (!IS_ALIGNED(extra_size, 16)) + goto invalid; + + if (base != userp) + goto invalid; + + /* Reject "unreasonably large" frames: */ + if (extra_size > sfp + SIGFRAME_MAXSZ - userp) + goto invalid; + + /* + * Ignore trailing terminator in __reserved[] + * and start parsing extra data: + */ + offset = 0; + limit = extra_size; + + if (!access_ok(VERIFY_READ, base, limit)) + goto invalid; + + continue; + + default: + goto invalid; + } + + if (size < sizeof(*head)) + goto invalid; + + if (limit - offset < size) + goto invalid; + + offset += size; + } + +done: + return 0; + +invalid: + return -EINVAL; +} + +static int restore_sigframe(struct pt_regs *regs, + struct rt_sigframe __user *sf) +{ + sigset_t set; + int i, err; + struct user_ctxs user; + + err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); + if (err == 0) + set_current_blocked(&set); + + for (i = 0; i < 31; i++) + __get_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i], + err); + __get_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err); + __get_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err); + __get_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err); + + /* + * Avoid sys_rt_sigreturn() restarting. + */ + forget_syscall(regs); + + err |= !valid_user_regs(®s->user_regs, current); + if (err == 0) + err = parse_user_sigframe(&user, sf); + + if (err == 0) { + if (!user.fpsimd) + return -EINVAL; + + if (user.sve) { + if (!system_supports_sve()) + return -EINVAL; + + err = restore_sve_fpsimd_context(&user); + } else { + err = restore_fpsimd_context(user.fpsimd); + } + } + + return err; +} + +SYSCALL_DEFINE0(rt_sigreturn) +{ + struct pt_regs *regs = current_pt_regs(); + struct 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 128-bit boundary, then 'sp' should + * be word aligned here. + */ + if (regs->sp & 15) + goto badframe; + + frame = (struct rt_sigframe __user *)regs->sp; + + if (!access_ok(VERIFY_READ, frame, sizeof (*frame))) + goto badframe; + + if (restore_sigframe(regs, frame)) + goto badframe; + + if (restore_altstack(&frame->uc.uc_stack)) + goto badframe; + + return regs->regs[0]; + +badframe: + arm64_notify_segfault(regs->sp); + return 0; +} + +/* + * Determine the layout of optional records in the signal frame + * + * add_all: if true, lays out the biggest possible signal frame for + * this task; otherwise, generates a layout for the current state + * of the task. + */ +static int setup_sigframe_layout(struct rt_sigframe_user_layout *user, + bool add_all) +{ + int err; + + err = sigframe_alloc(user, &user->fpsimd_offset, + sizeof(struct fpsimd_context)); + if (err) + return err; + + /* fault information, if valid */ + if (add_all || current->thread.fault_code) { + err = sigframe_alloc(user, &user->esr_offset, + sizeof(struct esr_context)); + if (err) + return err; + } + + if (system_supports_sve()) { + unsigned int vq = 0; + + if (add_all || test_thread_flag(TIF_SVE)) { + int vl = sve_max_vl; + + if (!add_all) + vl = current->thread.sve_vl; + + vq = sve_vq_from_vl(vl); + } + + err = sigframe_alloc(user, &user->sve_offset, + SVE_SIG_CONTEXT_SIZE(vq)); + if (err) + return err; + } + + return sigframe_alloc_end(user); +} + +static int setup_sigframe(struct rt_sigframe_user_layout *user, + struct pt_regs *regs, sigset_t *set) +{ + int i, err = 0; + struct rt_sigframe __user *sf = user->sigframe; + + /* set up the stack frame for unwinding */ + __put_user_error(regs->regs[29], &user->next_frame->fp, err); + __put_user_error(regs->regs[30], &user->next_frame->lr, err); + + for (i = 0; i < 31; i++) + __put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i], + err); + __put_user_error(regs->sp, &sf->uc.uc_mcontext.sp, err); + __put_user_error(regs->pc, &sf->uc.uc_mcontext.pc, err); + __put_user_error(regs->pstate, &sf->uc.uc_mcontext.pstate, err); + + __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err); + + err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); + + if (err == 0) { + struct fpsimd_context __user *fpsimd_ctx = + apply_user_offset(user, user->fpsimd_offset); + err |= preserve_fpsimd_context(fpsimd_ctx); + } + + /* fault information, if valid */ + if (err == 0 && user->esr_offset) { + struct esr_context __user *esr_ctx = + apply_user_offset(user, user->esr_offset); + + __put_user_error(ESR_MAGIC, &esr_ctx->head.magic, err); + __put_user_error(sizeof(*esr_ctx), &esr_ctx->head.size, err); + __put_user_error(current->thread.fault_code, &esr_ctx->esr, err); + } + + /* Scalable Vector Extension state, if present */ + if (system_supports_sve() && err == 0 && user->sve_offset) { + struct sve_context __user *sve_ctx = + apply_user_offset(user, user->sve_offset); + err |= preserve_sve_context(sve_ctx); + } + + if (err == 0 && user->extra_offset) { + char __user *sfp = (char __user *)user->sigframe; + char __user *userp = + apply_user_offset(user, user->extra_offset); + + struct extra_context __user *extra; + struct _aarch64_ctx __user *end; + u64 extra_datap; + u32 extra_size; + + extra = (struct extra_context __user *)userp; + userp += EXTRA_CONTEXT_SIZE; + + end = (struct _aarch64_ctx __user *)userp; + userp += TERMINATOR_SIZE; + + /* + * extra_datap is just written to the signal frame. + * The value gets cast back to a void __user * + * during sigreturn. + */ + extra_datap = (__force u64)userp; + extra_size = sfp + round_up(user->size, 16) - userp; + + __put_user_error(EXTRA_MAGIC, &extra->head.magic, err); + __put_user_error(EXTRA_CONTEXT_SIZE, &extra->head.size, err); + __put_user_error(extra_datap, &extra->datap, err); + __put_user_error(extra_size, &extra->size, err); + + /* Add the terminator */ + __put_user_error(0, &end->magic, err); + __put_user_error(0, &end->size, err); + } + + /* set the "end" magic */ + if (err == 0) { + struct _aarch64_ctx __user *end = + apply_user_offset(user, user->end_offset); + + __put_user_error(0, &end->magic, err); + __put_user_error(0, &end->size, err); + } + + return err; +} + +static int get_sigframe(struct rt_sigframe_user_layout *user, + struct ksignal *ksig, struct pt_regs *regs) +{ + unsigned long sp, sp_top; + int err; + + init_user_layout(user); + err = setup_sigframe_layout(user, false); + if (err) + return err; + + sp = sp_top = sigsp(regs->sp, ksig); + + sp = round_down(sp - sizeof(struct frame_record), 16); + user->next_frame = (struct frame_record __user *)sp; + + sp = round_down(sp, 16) - sigframe_size(user); + user->sigframe = (struct rt_sigframe __user *)sp; + + /* + * Check that we can actually write to the signal frame. + */ + if (!access_ok(VERIFY_WRITE, user->sigframe, sp_top - sp)) + return -EFAULT; + + return 0; +} + +static void setup_return(struct pt_regs *regs, struct k_sigaction *ka, + struct rt_sigframe_user_layout *user, int usig) +{ + __sigrestore_t sigtramp; + + regs->regs[0] = usig; + regs->sp = (unsigned long)user->sigframe; + regs->regs[29] = (unsigned long)&user->next_frame->fp; + regs->pc = (unsigned long)ka->sa.sa_handler; + + if (ka->sa.sa_flags & SA_RESTORER) + sigtramp = ka->sa.sa_restorer; + else + sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp); + + regs->regs[30] = (unsigned long)sigtramp; +} + +static int setup_rt_frame(int usig, struct ksignal *ksig, sigset_t *set, + struct pt_regs *regs) +{ + struct rt_sigframe_user_layout user; + struct rt_sigframe __user *frame; + int err = 0; + + fpsimd_signal_preserve_current_state(); + + if (get_sigframe(&user, ksig, regs)) + return 1; + + frame = user.sigframe; + + __put_user_error(0, &frame->uc.uc_flags, err); + __put_user_error(NULL, &frame->uc.uc_link, err); + + err |= __save_altstack(&frame->uc.uc_stack, regs->sp); + err |= setup_sigframe(&user, regs, set); + if (err == 0) { + setup_return(regs, &ksig->ka, &user, usig); + if (ksig->ka.sa.sa_flags & SA_SIGINFO) { + err |= copy_siginfo_to_user(&frame->info, &ksig->info); + regs->regs[1] = (unsigned long)&frame->info; + regs->regs[2] = (unsigned long)&frame->uc; + } + } + + return err; +} + +static void setup_restart_syscall(struct pt_regs *regs) +{ + if (is_compat_task()) + compat_setup_restart_syscall(regs); + else + regs->regs[8] = __NR_restart_syscall; +} + +/* + * OK, we're invoking a handler + */ +static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) +{ + sigset_t *oldset = sigmask_to_save(); + int usig = ksig->sig; + int ret; + + rseq_signal_deliver(ksig, regs); + + /* + * Set up the stack frame + */ + if (is_compat_task()) { + if (ksig->ka.sa.sa_flags & SA_SIGINFO) + ret = compat_setup_rt_frame(usig, ksig, oldset, regs); + else + ret = compat_setup_frame(usig, ksig, oldset, regs); + } else { + ret = setup_rt_frame(usig, ksig, oldset, regs); + } + + /* + * Check that the resulting registers are actually sane. + */ + ret |= !valid_user_regs(®s->user_regs, current); + + /* Step into the signal handler if we are stepping */ + signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP)); +} + +/* + * Note that 'init' is a special process: it doesn't get signals it doesn't + * want to handle. Thus you cannot kill init even with a SIGKILL even by + * mistake. + * + * Note that we go through the signals twice: once to check the signals that + * the kernel can handle, and then we build all the user-level signal handling + * stack-frames in one go after that. + */ +static void do_signal(struct pt_regs *regs) +{ + unsigned long continue_addr = 0, restart_addr = 0; + int retval = 0; + struct ksignal ksig; + bool syscall = in_syscall(regs); + + /* + * If we were from a system call, check for system call restarting... + */ + if (syscall) { + continue_addr = regs->pc; + restart_addr = continue_addr - (compat_thumb_mode(regs) ? 2 : 4); + retval = regs->regs[0]; + + /* + * Avoid additional syscall restarting via ret_to_user. + */ + forget_syscall(regs); + + /* + * Prepare for system call restart. We do this here so that a + * debugger will see the already changed PC. + */ + switch (retval) { + case -ERESTARTNOHAND: + case -ERESTARTSYS: + case -ERESTARTNOINTR: + case -ERESTART_RESTARTBLOCK: + regs->regs[0] = regs->orig_x0; + regs->pc = restart_addr; + break; + } + } + + /* + * Get the signal to deliver. When running under ptrace, at this point + * the debugger may change all of our registers. + */ + if (get_signal(&ksig)) { + /* + * Depending on the signal settings, we may need to revert the + * decision to restart the system call, but skip this if a + * debugger has chosen to restart at a different PC. + */ + if (regs->pc == restart_addr && + (retval == -ERESTARTNOHAND || + retval == -ERESTART_RESTARTBLOCK || + (retval == -ERESTARTSYS && + !(ksig.ka.sa.sa_flags & SA_RESTART)))) { + regs->regs[0] = -EINTR; + regs->pc = continue_addr; + } + + handle_signal(&ksig, regs); + return; + } + + /* + * Handle restarting a different system call. As above, if a debugger + * has chosen to restart at a different PC, ignore the restart. + */ + if (syscall && regs->pc == restart_addr) { + if (retval == -ERESTART_RESTARTBLOCK) + setup_restart_syscall(regs); + user_rewind_single_step(current); + } + + restore_saved_sigmask(); +} + +asmlinkage void do_notify_resume(struct pt_regs *regs, + unsigned long thread_flags) +{ + /* + * The assembly code enters us with IRQs off, but it hasn't + * informed the tracing code of that for efficiency reasons. + * Update the trace code with the current status. + */ + trace_hardirqs_off(); + + do { + /* Check valid user FS if needed */ + addr_limit_user_check(); + + if (thread_flags & _TIF_NEED_RESCHED) { + /* Unmask Debug and SError for the next task */ + local_daif_restore(DAIF_PROCCTX_NOIRQ); + + schedule(); + } else { + local_daif_restore(DAIF_PROCCTX); + + if (thread_flags & _TIF_UPROBE) + uprobe_notify_resume(regs); + + if (thread_flags & _TIF_SIGPENDING) + do_signal(regs); + + if (thread_flags & _TIF_NOTIFY_RESUME) { + clear_thread_flag(TIF_NOTIFY_RESUME); + tracehook_notify_resume(regs); + rseq_handle_notify_resume(NULL, regs); + } + + if (thread_flags & _TIF_FOREIGN_FPSTATE) + fpsimd_restore_current_state(); + } + + local_daif_mask(); + thread_flags = READ_ONCE(current_thread_info()->flags); + } while (thread_flags & _TIF_WORK_MASK); +} + +unsigned long __ro_after_init signal_minsigstksz; + +/* + * Determine the stack space required for guaranteed signal devliery. + * This function is used to populate AT_MINSIGSTKSZ at process startup. + * cpufeatures setup is assumed to be complete. + */ +void __init minsigstksz_setup(void) +{ + struct rt_sigframe_user_layout user; + + init_user_layout(&user); + + /* + * If this fails, SIGFRAME_MAXSZ needs to be enlarged. It won't + * be big enough, but it's our best guess: + */ + if (WARN_ON(setup_sigframe_layout(&user, true))) + return; + + signal_minsigstksz = sigframe_size(&user) + + round_up(sizeof(struct frame_record), 16) + + 16; /* max alignment padding */ +} |