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Diffstat (limited to 'arch/x86/kernel/signal_64.c')
-rw-r--r--arch/x86/kernel/signal_64.c495
1 files changed, 495 insertions, 0 deletions
diff --git a/arch/x86/kernel/signal_64.c b/arch/x86/kernel/signal_64.c
new file mode 100644
index 000000000000..739175b01e06
--- /dev/null
+++ b/arch/x86/kernel/signal_64.c
@@ -0,0 +1,495 @@
+/*
+ * linux/arch/x86_64/kernel/signal.c
+ *
+ * Copyright (C) 1991, 1992 Linus Torvalds
+ * Copyright (C) 2000, 2001, 2002 Andi Kleen SuSE Labs
+ *
+ * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
+ * 2000-06-20 Pentium III FXSR, SSE support by Gareth Hughes
+ * 2000-2002 x86-64 support by Andi Kleen
+ */
+
+#include <linux/sched.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/unistd.h>
+#include <linux/stddef.h>
+#include <linux/personality.h>
+#include <linux/compiler.h>
+#include <asm/ucontext.h>
+#include <asm/uaccess.h>
+#include <asm/i387.h>
+#include <asm/proto.h>
+#include <asm/ia32_unistd.h>
+#include <asm/mce.h>
+
+/* #define DEBUG_SIG 1 */
+
+#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
+
+int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
+ sigset_t *set, struct pt_regs * regs);
+int ia32_setup_frame(int sig, struct k_sigaction *ka,
+ sigset_t *set, struct pt_regs * regs);
+
+asmlinkage long
+sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
+ struct pt_regs *regs)
+{
+ return do_sigaltstack(uss, uoss, regs->rsp);
+}
+
+
+/*
+ * Do a signal return; undo the signal stack.
+ */
+
+struct rt_sigframe
+{
+ char __user *pretcode;
+ struct ucontext uc;
+ struct siginfo info;
+};
+
+static int
+restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned long *prax)
+{
+ unsigned int err = 0;
+
+ /* Always make any pending restarted system calls return -EINTR */
+ current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
+#define COPY(x) err |= __get_user(regs->x, &sc->x)
+
+ COPY(rdi); COPY(rsi); COPY(rbp); COPY(rsp); COPY(rbx);
+ COPY(rdx); COPY(rcx); COPY(rip);
+ COPY(r8);
+ COPY(r9);
+ COPY(r10);
+ COPY(r11);
+ COPY(r12);
+ COPY(r13);
+ COPY(r14);
+ COPY(r15);
+
+ /* Kernel saves and restores only the CS segment register on signals,
+ * which is the bare minimum needed to allow mixed 32/64-bit code.
+ * App's signal handler can save/restore other segments if needed. */
+ {
+ unsigned cs;
+ err |= __get_user(cs, &sc->cs);
+ regs->cs = cs | 3; /* Force into user mode */
+ }
+
+ {
+ unsigned int tmpflags;
+ err |= __get_user(tmpflags, &sc->eflags);
+ regs->eflags = (regs->eflags & ~0x40DD5) | (tmpflags & 0x40DD5);
+ regs->orig_rax = -1; /* disable syscall checks */
+ }
+
+ {
+ struct _fpstate __user * buf;
+ err |= __get_user(buf, &sc->fpstate);
+
+ if (buf) {
+ if (!access_ok(VERIFY_READ, buf, sizeof(*buf)))
+ goto badframe;
+ err |= restore_i387(buf);
+ } else {
+ struct task_struct *me = current;
+ if (used_math()) {
+ clear_fpu(me);
+ clear_used_math();
+ }
+ }
+ }
+
+ err |= __get_user(*prax, &sc->rax);
+ return err;
+
+badframe:
+ return 1;
+}
+
+asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
+{
+ struct rt_sigframe __user *frame;
+ sigset_t set;
+ unsigned long eax;
+
+ frame = (struct rt_sigframe __user *)(regs->rsp - 8);
+ if (!access_ok(VERIFY_READ, frame, sizeof(*frame))) {
+ goto badframe;
+ }
+ if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) {
+ goto badframe;
+ }
+
+ sigdelsetmask(&set, ~_BLOCKABLE);
+ spin_lock_irq(&current->sighand->siglock);
+ current->blocked = set;
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+
+ if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &eax))
+ goto badframe;
+
+#ifdef DEBUG_SIG
+ printk("%d sigreturn rip:%lx rsp:%lx frame:%p rax:%lx\n",current->pid,regs->rip,regs->rsp,frame,eax);
+#endif
+
+ if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->rsp) == -EFAULT)
+ goto badframe;
+
+ return eax;
+
+badframe:
+ signal_fault(regs,frame,"sigreturn");
+ return 0;
+}
+
+/*
+ * Set up a signal frame.
+ */
+
+static inline int
+setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me)
+{
+ int err = 0;
+
+ err |= __put_user(regs->cs, &sc->cs);
+ err |= __put_user(0, &sc->gs);
+ err |= __put_user(0, &sc->fs);
+
+ err |= __put_user(regs->rdi, &sc->rdi);
+ err |= __put_user(regs->rsi, &sc->rsi);
+ err |= __put_user(regs->rbp, &sc->rbp);
+ err |= __put_user(regs->rsp, &sc->rsp);
+ err |= __put_user(regs->rbx, &sc->rbx);
+ err |= __put_user(regs->rdx, &sc->rdx);
+ err |= __put_user(regs->rcx, &sc->rcx);
+ err |= __put_user(regs->rax, &sc->rax);
+ err |= __put_user(regs->r8, &sc->r8);
+ err |= __put_user(regs->r9, &sc->r9);
+ err |= __put_user(regs->r10, &sc->r10);
+ err |= __put_user(regs->r11, &sc->r11);
+ err |= __put_user(regs->r12, &sc->r12);
+ err |= __put_user(regs->r13, &sc->r13);
+ err |= __put_user(regs->r14, &sc->r14);
+ err |= __put_user(regs->r15, &sc->r15);
+ err |= __put_user(me->thread.trap_no, &sc->trapno);
+ err |= __put_user(me->thread.error_code, &sc->err);
+ err |= __put_user(regs->rip, &sc->rip);
+ err |= __put_user(regs->eflags, &sc->eflags);
+ err |= __put_user(mask, &sc->oldmask);
+ err |= __put_user(me->thread.cr2, &sc->cr2);
+
+ return err;
+}
+
+/*
+ * Determine which stack to use..
+ */
+
+static void __user *
+get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
+{
+ unsigned long rsp;
+
+ /* Default to using normal stack - redzone*/
+ rsp = regs->rsp - 128;
+
+ /* This is the X/Open sanctioned signal stack switching. */
+ if (ka->sa.sa_flags & SA_ONSTACK) {
+ if (sas_ss_flags(rsp) == 0)
+ rsp = current->sas_ss_sp + current->sas_ss_size;
+ }
+
+ return (void __user *)round_down(rsp - size, 16);
+}
+
+static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
+ sigset_t *set, struct pt_regs * regs)
+{
+ struct rt_sigframe __user *frame;
+ struct _fpstate __user *fp = NULL;
+ int err = 0;
+ struct task_struct *me = current;
+
+ if (used_math()) {
+ fp = get_stack(ka, regs, sizeof(struct _fpstate));
+ frame = (void __user *)round_down(
+ (unsigned long)fp - sizeof(struct rt_sigframe), 16) - 8;
+
+ if (!access_ok(VERIFY_WRITE, fp, sizeof(struct _fpstate)))
+ goto give_sigsegv;
+
+ if (save_i387(fp) < 0)
+ err |= -1;
+ } else
+ frame = get_stack(ka, regs, sizeof(struct rt_sigframe)) - 8;
+
+ if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
+ goto give_sigsegv;
+
+ if (ka->sa.sa_flags & SA_SIGINFO) {
+ err |= copy_siginfo_to_user(&frame->info, info);
+ if (err)
+ goto give_sigsegv;
+ }
+
+ /* Create the ucontext. */
+ err |= __put_user(0, &frame->uc.uc_flags);
+ err |= __put_user(0, &frame->uc.uc_link);
+ err |= __put_user(me->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
+ err |= __put_user(sas_ss_flags(regs->rsp),
+ &frame->uc.uc_stack.ss_flags);
+ err |= __put_user(me->sas_ss_size, &frame->uc.uc_stack.ss_size);
+ err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0], me);
+ err |= __put_user(fp, &frame->uc.uc_mcontext.fpstate);
+ if (sizeof(*set) == 16) {
+ __put_user(set->sig[0], &frame->uc.uc_sigmask.sig[0]);
+ __put_user(set->sig[1], &frame->uc.uc_sigmask.sig[1]);
+ } else
+ err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
+
+ /* Set up to return from userspace. If provided, use a stub
+ already in userspace. */
+ /* x86-64 should always use SA_RESTORER. */
+ if (ka->sa.sa_flags & SA_RESTORER) {
+ err |= __put_user(ka->sa.sa_restorer, &frame->pretcode);
+ } else {
+ /* could use a vstub here */
+ goto give_sigsegv;
+ }
+
+ if (err)
+ goto give_sigsegv;
+
+#ifdef DEBUG_SIG
+ printk("%d old rip %lx old rsp %lx old rax %lx\n", current->pid,regs->rip,regs->rsp,regs->rax);
+#endif
+
+ /* Set up registers for signal handler */
+ regs->rdi = sig;
+ /* In case the signal handler was declared without prototypes */
+ regs->rax = 0;
+
+ /* This also works for non SA_SIGINFO handlers because they expect the
+ next argument after the signal number on the stack. */
+ regs->rsi = (unsigned long)&frame->info;
+ regs->rdx = (unsigned long)&frame->uc;
+ regs->rip = (unsigned long) ka->sa.sa_handler;
+
+ regs->rsp = (unsigned long)frame;
+
+ /* Set up the CS register to run signal handlers in 64-bit mode,
+ even if the handler happens to be interrupting 32-bit code. */
+ regs->cs = __USER_CS;
+
+ /* This, by contrast, has nothing to do with segment registers -
+ see include/asm-x86_64/uaccess.h for details. */
+ set_fs(USER_DS);
+
+ regs->eflags &= ~TF_MASK;
+ if (test_thread_flag(TIF_SINGLESTEP))
+ ptrace_notify(SIGTRAP);
+#ifdef DEBUG_SIG
+ printk("SIG deliver (%s:%d): sp=%p pc=%lx ra=%p\n",
+ current->comm, current->pid, frame, regs->rip, frame->pretcode);
+#endif
+
+ return 0;
+
+give_sigsegv:
+ force_sigsegv(sig, current);
+ return -EFAULT;
+}
+
+/*
+ * OK, we're invoking a handler
+ */
+
+static int
+handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
+ sigset_t *oldset, struct pt_regs *regs)
+{
+ int ret;
+
+#ifdef DEBUG_SIG
+ printk("handle_signal pid:%d sig:%lu rip:%lx rsp:%lx regs=%p\n",
+ current->pid, sig,
+ regs->rip, regs->rsp, regs);
+#endif
+
+ /* Are we from a system call? */
+ if ((long)regs->orig_rax >= 0) {
+ /* If so, check system call restarting.. */
+ switch (regs->rax) {
+ case -ERESTART_RESTARTBLOCK:
+ case -ERESTARTNOHAND:
+ regs->rax = -EINTR;
+ break;
+
+ case -ERESTARTSYS:
+ if (!(ka->sa.sa_flags & SA_RESTART)) {
+ regs->rax = -EINTR;
+ break;
+ }
+ /* fallthrough */
+ case -ERESTARTNOINTR:
+ regs->rax = regs->orig_rax;
+ regs->rip -= 2;
+ break;
+ }
+ }
+
+ /*
+ * If TF is set due to a debugger (PT_DTRACE), clear the TF
+ * flag so that register information in the sigcontext is
+ * correct.
+ */
+ if (unlikely(regs->eflags & TF_MASK)) {
+ if (likely(current->ptrace & PT_DTRACE)) {
+ current->ptrace &= ~PT_DTRACE;
+ regs->eflags &= ~TF_MASK;
+ }
+ }
+
+#ifdef CONFIG_IA32_EMULATION
+ if (test_thread_flag(TIF_IA32)) {
+ if (ka->sa.sa_flags & SA_SIGINFO)
+ ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
+ else
+ ret = ia32_setup_frame(sig, ka, oldset, regs);
+ } else
+#endif
+ ret = setup_rt_frame(sig, ka, info, oldset, regs);
+
+ if (ret == 0) {
+ spin_lock_irq(&current->sighand->siglock);
+ sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
+ if (!(ka->sa.sa_flags & SA_NODEFER))
+ sigaddset(&current->blocked,sig);
+ recalc_sigpending();
+ spin_unlock_irq(&current->sighand->siglock);
+ }
+
+ return ret;
+}
+
+/*
+ * 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.
+ */
+static void do_signal(struct pt_regs *regs)
+{
+ struct k_sigaction ka;
+ siginfo_t info;
+ int signr;
+ sigset_t *oldset;
+
+ /*
+ * We want the common case to go fast, which
+ * is why we may in certain cases get here from
+ * kernel mode. Just return without doing anything
+ * if so.
+ */
+ if (!user_mode(regs))
+ return;
+
+ if (test_thread_flag(TIF_RESTORE_SIGMASK))
+ oldset = &current->saved_sigmask;
+ else
+ oldset = &current->blocked;
+
+ signr = get_signal_to_deliver(&info, &ka, regs, NULL);
+ if (signr > 0) {
+ /* Reenable any watchpoints before delivering the
+ * signal to user space. The processor register will
+ * have been cleared if the watchpoint triggered
+ * inside the kernel.
+ */
+ if (current->thread.debugreg7)
+ set_debugreg(current->thread.debugreg7, 7);
+
+ /* Whee! Actually deliver the signal. */
+ if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
+ /* a signal was successfully delivered; the saved
+ * sigmask will have been stored in the signal frame,
+ * and will be restored by sigreturn, so we can simply
+ * clear the TIF_RESTORE_SIGMASK flag */
+ clear_thread_flag(TIF_RESTORE_SIGMASK);
+ }
+ return;
+ }
+
+ /* Did we come from a system call? */
+ if ((long)regs->orig_rax >= 0) {
+ /* Restart the system call - no handlers present */
+ long res = regs->rax;
+ switch (res) {
+ case -ERESTARTNOHAND:
+ case -ERESTARTSYS:
+ case -ERESTARTNOINTR:
+ regs->rax = regs->orig_rax;
+ regs->rip -= 2;
+ break;
+ case -ERESTART_RESTARTBLOCK:
+ regs->rax = test_thread_flag(TIF_IA32) ?
+ __NR_ia32_restart_syscall :
+ __NR_restart_syscall;
+ regs->rip -= 2;
+ break;
+ }
+ }
+
+ /* if there's no signal to deliver, we just put the saved sigmask
+ back. */
+ if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
+ clear_thread_flag(TIF_RESTORE_SIGMASK);
+ sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
+ }
+}
+
+void
+do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
+{
+#ifdef DEBUG_SIG
+ printk("do_notify_resume flags:%x rip:%lx rsp:%lx caller:%p pending:%x\n",
+ thread_info_flags, regs->rip, regs->rsp, __builtin_return_address(0),signal_pending(current));
+#endif
+
+ /* Pending single-step? */
+ if (thread_info_flags & _TIF_SINGLESTEP) {
+ regs->eflags |= TF_MASK;
+ clear_thread_flag(TIF_SINGLESTEP);
+ }
+
+#ifdef CONFIG_X86_MCE
+ /* notify userspace of pending MCEs */
+ if (thread_info_flags & _TIF_MCE_NOTIFY)
+ mce_notify_user();
+#endif /* CONFIG_X86_MCE */
+
+ /* deal with pending signal delivery */
+ if (thread_info_flags & (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK))
+ do_signal(regs);
+}
+
+void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
+{
+ struct task_struct *me = current;
+ if (show_unhandled_signals && printk_ratelimit())
+ printk("%s[%d] bad frame in %s frame:%p rip:%lx rsp:%lx orax:%lx\n",
+ me->comm,me->pid,where,frame,regs->rip,regs->rsp,regs->orig_rax);
+
+ force_sig(SIGSEGV, me);
+}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.