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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /arch/arm/kernel/signal.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/arm/kernel/signal.c')
-rw-r--r-- | arch/arm/kernel/signal.c | 716 |
1 files changed, 716 insertions, 0 deletions
diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c new file mode 100644 index 000000000..e07f35925 --- /dev/null +++ b/arch/arm/kernel/signal.c @@ -0,0 +1,716 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * linux/arch/arm/kernel/signal.c + * + * Copyright (C) 1995-2009 Russell King + */ +#include <linux/errno.h> +#include <linux/random.h> +#include <linux/signal.h> +#include <linux/personality.h> +#include <linux/uaccess.h> +#include <linux/resume_user_mode.h> +#include <linux/uprobes.h> +#include <linux/syscalls.h> + +#include <asm/elf.h> +#include <asm/cacheflush.h> +#include <asm/traps.h> +#include <asm/unistd.h> +#include <asm/vfp.h> + +#include "signal.h" + +extern const unsigned long sigreturn_codes[17]; + +static unsigned long signal_return_offset; + +#ifdef CONFIG_IWMMXT + +static int preserve_iwmmxt_context(struct iwmmxt_sigframe __user *frame) +{ + char kbuf[sizeof(*frame) + 8]; + struct iwmmxt_sigframe *kframe; + int err = 0; + + /* the iWMMXt context must be 64 bit aligned */ + kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); + + if (test_thread_flag(TIF_USING_IWMMXT)) { + kframe->magic = IWMMXT_MAGIC; + kframe->size = IWMMXT_STORAGE_SIZE; + iwmmxt_task_copy(current_thread_info(), &kframe->storage); + } else { + /* + * For bug-compatibility with older kernels, some space + * has to be reserved for iWMMXt even if it's not used. + * Set the magic and size appropriately so that properly + * written userspace can skip it reliably: + */ + *kframe = (struct iwmmxt_sigframe) { + .magic = DUMMY_MAGIC, + .size = IWMMXT_STORAGE_SIZE, + }; + } + + err = __copy_to_user(frame, kframe, sizeof(*kframe)); + + return err; +} + +static int restore_iwmmxt_context(char __user **auxp) +{ + struct iwmmxt_sigframe __user *frame = + (struct iwmmxt_sigframe __user *)*auxp; + char kbuf[sizeof(*frame) + 8]; + struct iwmmxt_sigframe *kframe; + + /* the iWMMXt context must be 64 bit aligned */ + kframe = (struct iwmmxt_sigframe *)((unsigned long)(kbuf + 8) & ~7); + if (__copy_from_user(kframe, frame, sizeof(*frame))) + return -1; + + /* + * For non-iWMMXt threads: a single iwmmxt_sigframe-sized dummy + * block is discarded for compatibility with setup_sigframe() if + * present, but we don't mandate its presence. If some other + * magic is here, it's not for us: + */ + if (!test_thread_flag(TIF_USING_IWMMXT) && + kframe->magic != DUMMY_MAGIC) + return 0; + + if (kframe->size != IWMMXT_STORAGE_SIZE) + return -1; + + if (test_thread_flag(TIF_USING_IWMMXT)) { + if (kframe->magic != IWMMXT_MAGIC) + return -1; + + iwmmxt_task_restore(current_thread_info(), &kframe->storage); + } + + *auxp += IWMMXT_STORAGE_SIZE; + return 0; +} + +#endif + +#ifdef CONFIG_VFP + +static int preserve_vfp_context(struct vfp_sigframe __user *frame) +{ + struct vfp_sigframe kframe; + int err = 0; + + memset(&kframe, 0, sizeof(kframe)); + kframe.magic = VFP_MAGIC; + kframe.size = VFP_STORAGE_SIZE; + + err = vfp_preserve_user_clear_hwstate(&kframe.ufp, &kframe.ufp_exc); + if (err) + return err; + + return __copy_to_user(frame, &kframe, sizeof(kframe)); +} + +static int restore_vfp_context(char __user **auxp) +{ + struct vfp_sigframe frame; + int err; + + err = __copy_from_user(&frame, *auxp, sizeof(frame)); + if (err) + return err; + + if (frame.magic != VFP_MAGIC || frame.size != VFP_STORAGE_SIZE) + return -EINVAL; + + *auxp += sizeof(frame); + return vfp_restore_user_hwstate(&frame.ufp, &frame.ufp_exc); +} + +#endif + +/* + * Do a signal return; undo the signal stack. These are aligned to 64-bit. + */ + +static int restore_sigframe(struct pt_regs *regs, struct sigframe __user *sf) +{ + struct sigcontext context; + char __user *aux; + sigset_t set; + int err; + + err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set)); + if (err == 0) + set_current_blocked(&set); + + err |= __copy_from_user(&context, &sf->uc.uc_mcontext, sizeof(context)); + if (err == 0) { + regs->ARM_r0 = context.arm_r0; + regs->ARM_r1 = context.arm_r1; + regs->ARM_r2 = context.arm_r2; + regs->ARM_r3 = context.arm_r3; + regs->ARM_r4 = context.arm_r4; + regs->ARM_r5 = context.arm_r5; + regs->ARM_r6 = context.arm_r6; + regs->ARM_r7 = context.arm_r7; + regs->ARM_r8 = context.arm_r8; + regs->ARM_r9 = context.arm_r9; + regs->ARM_r10 = context.arm_r10; + regs->ARM_fp = context.arm_fp; + regs->ARM_ip = context.arm_ip; + regs->ARM_sp = context.arm_sp; + regs->ARM_lr = context.arm_lr; + regs->ARM_pc = context.arm_pc; + regs->ARM_cpsr = context.arm_cpsr; + } + + err |= !valid_user_regs(regs); + + aux = (char __user *) sf->uc.uc_regspace; +#ifdef CONFIG_IWMMXT + if (err == 0) + err |= restore_iwmmxt_context(&aux); +#endif +#ifdef CONFIG_VFP + if (err == 0) + err |= restore_vfp_context(&aux); +#endif + + return err; +} + +asmlinkage int sys_sigreturn(struct pt_regs *regs) +{ + struct 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->ARM_sp & 7) + goto badframe; + + frame = (struct sigframe __user *)regs->ARM_sp; + + if (!access_ok(frame, sizeof (*frame))) + goto badframe; + + if (restore_sigframe(regs, frame)) + goto badframe; + + return regs->ARM_r0; + +badframe: + force_sig(SIGSEGV); + return 0; +} + +asmlinkage int sys_rt_sigreturn(struct pt_regs *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 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->ARM_sp & 7) + goto badframe; + + frame = (struct rt_sigframe __user *)regs->ARM_sp; + + if (!access_ok(frame, sizeof (*frame))) + goto badframe; + + if (restore_sigframe(regs, &frame->sig)) + goto badframe; + + if (restore_altstack(&frame->sig.uc.uc_stack)) + goto badframe; + + return regs->ARM_r0; + +badframe: + force_sig(SIGSEGV); + return 0; +} + +static int +setup_sigframe(struct sigframe __user *sf, struct pt_regs *regs, sigset_t *set) +{ + struct aux_sigframe __user *aux; + struct sigcontext context; + int err = 0; + + context = (struct sigcontext) { + .arm_r0 = regs->ARM_r0, + .arm_r1 = regs->ARM_r1, + .arm_r2 = regs->ARM_r2, + .arm_r3 = regs->ARM_r3, + .arm_r4 = regs->ARM_r4, + .arm_r5 = regs->ARM_r5, + .arm_r6 = regs->ARM_r6, + .arm_r7 = regs->ARM_r7, + .arm_r8 = regs->ARM_r8, + .arm_r9 = regs->ARM_r9, + .arm_r10 = regs->ARM_r10, + .arm_fp = regs->ARM_fp, + .arm_ip = regs->ARM_ip, + .arm_sp = regs->ARM_sp, + .arm_lr = regs->ARM_lr, + .arm_pc = regs->ARM_pc, + .arm_cpsr = regs->ARM_cpsr, + + .trap_no = current->thread.trap_no, + .error_code = current->thread.error_code, + .fault_address = current->thread.address, + .oldmask = set->sig[0], + }; + + err |= __copy_to_user(&sf->uc.uc_mcontext, &context, sizeof(context)); + + err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set)); + + aux = (struct aux_sigframe __user *) sf->uc.uc_regspace; +#ifdef CONFIG_IWMMXT + if (err == 0) + err |= preserve_iwmmxt_context(&aux->iwmmxt); +#endif +#ifdef CONFIG_VFP + if (err == 0) + err |= preserve_vfp_context(&aux->vfp); +#endif + err |= __put_user(0, &aux->end_magic); + + return err; +} + +static inline void __user * +get_sigframe(struct ksignal *ksig, struct pt_regs *regs, int framesize) +{ + unsigned long sp = sigsp(regs->ARM_sp, ksig); + void __user *frame; + + /* + * ATPCS B01 mandates 8-byte alignment + */ + frame = (void __user *)((sp - framesize) & ~7); + + /* + * Check that we can actually write to the signal frame. + */ + if (!access_ok(frame, framesize)) + frame = NULL; + + return frame; +} + +static int +setup_return(struct pt_regs *regs, struct ksignal *ksig, + unsigned long __user *rc, void __user *frame) +{ + unsigned long handler = (unsigned long)ksig->ka.sa.sa_handler; + unsigned long handler_fdpic_GOT = 0; + unsigned long retcode; + unsigned int idx, thumb = 0; + unsigned long cpsr = regs->ARM_cpsr & ~(PSR_f | PSR_E_BIT); + bool fdpic = IS_ENABLED(CONFIG_BINFMT_ELF_FDPIC) && + (current->personality & FDPIC_FUNCPTRS); + + if (fdpic) { + unsigned long __user *fdpic_func_desc = + (unsigned long __user *)handler; + if (__get_user(handler, &fdpic_func_desc[0]) || + __get_user(handler_fdpic_GOT, &fdpic_func_desc[1])) + return 1; + } + + cpsr |= PSR_ENDSTATE; + + /* + * Maybe we need to deliver a 32-bit signal to a 26-bit task. + */ + if (ksig->ka.sa.sa_flags & SA_THIRTYTWO) + cpsr = (cpsr & ~MODE_MASK) | USR_MODE; + +#ifdef CONFIG_ARM_THUMB + if (elf_hwcap & HWCAP_THUMB) { + /* + * The LSB of the handler determines if we're going to + * be using THUMB or ARM mode for this signal handler. + */ + thumb = handler & 1; + + /* + * Clear the If-Then Thumb-2 execution state. ARM spec + * requires this to be all 000s in ARM mode. Snapdragon + * S4/Krait misbehaves on a Thumb=>ARM signal transition + * without this. + * + * We must do this whenever we are running on a Thumb-2 + * capable CPU, which includes ARMv6T2. However, we elect + * to always do this to simplify the code; this field is + * marked UNK/SBZP for older architectures. + */ + cpsr &= ~PSR_IT_MASK; + + if (thumb) { + cpsr |= PSR_T_BIT; + } else + cpsr &= ~PSR_T_BIT; + } +#endif + + if (ksig->ka.sa.sa_flags & SA_RESTORER) { + retcode = (unsigned long)ksig->ka.sa.sa_restorer; + if (fdpic) { + /* + * We need code to load the function descriptor. + * That code follows the standard sigreturn code + * (6 words), and is made of 3 + 2 words for each + * variant. The 4th copied word is the actual FD + * address that the assembly code expects. + */ + idx = 6 + thumb * 3; + if (ksig->ka.sa.sa_flags & SA_SIGINFO) + idx += 5; + if (__put_user(sigreturn_codes[idx], rc ) || + __put_user(sigreturn_codes[idx+1], rc+1) || + __put_user(sigreturn_codes[idx+2], rc+2) || + __put_user(retcode, rc+3)) + return 1; + goto rc_finish; + } + } else { + idx = thumb << 1; + if (ksig->ka.sa.sa_flags & SA_SIGINFO) + idx += 3; + + /* + * Put the sigreturn code on the stack no matter which return + * mechanism we use in order to remain ABI compliant + */ + if (__put_user(sigreturn_codes[idx], rc) || + __put_user(sigreturn_codes[idx+1], rc+1)) + return 1; + +rc_finish: +#ifdef CONFIG_MMU + if (cpsr & MODE32_BIT) { + struct mm_struct *mm = current->mm; + + /* + * 32-bit code can use the signal return page + * except when the MPU has protected the vectors + * page from PL0 + */ + retcode = mm->context.sigpage + signal_return_offset + + (idx << 2) + thumb; + } else +#endif + { + /* + * Ensure that the instruction cache sees + * the return code written onto the stack. + */ + flush_icache_range((unsigned long)rc, + (unsigned long)(rc + 3)); + + retcode = ((unsigned long)rc) + thumb; + } + } + + regs->ARM_r0 = ksig->sig; + regs->ARM_sp = (unsigned long)frame; + regs->ARM_lr = retcode; + regs->ARM_pc = handler; + if (fdpic) + regs->ARM_r9 = handler_fdpic_GOT; + regs->ARM_cpsr = cpsr; + + return 0; +} + +static int +setup_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) +{ + struct sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); + int err = 0; + + if (!frame) + return 1; + + /* + * Set uc.uc_flags to a value which sc.trap_no would never have. + */ + err = __put_user(0x5ac3c35a, &frame->uc.uc_flags); + + err |= setup_sigframe(frame, regs, set); + if (err == 0) + err = setup_return(regs, ksig, frame->retcode, frame); + + return err; +} + +static int +setup_rt_frame(struct ksignal *ksig, sigset_t *set, struct pt_regs *regs) +{ + struct rt_sigframe __user *frame = get_sigframe(ksig, regs, sizeof(*frame)); + int err = 0; + + if (!frame) + return 1; + + err |= copy_siginfo_to_user(&frame->info, &ksig->info); + + err |= __put_user(0, &frame->sig.uc.uc_flags); + err |= __put_user(NULL, &frame->sig.uc.uc_link); + + err |= __save_altstack(&frame->sig.uc.uc_stack, regs->ARM_sp); + err |= setup_sigframe(&frame->sig, regs, set); + if (err == 0) + err = setup_return(regs, ksig, frame->sig.retcode, frame); + + if (err == 0) { + /* + * For realtime signals we must also set the second and third + * arguments for the signal handler. + * -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06 + */ + regs->ARM_r1 = (unsigned long)&frame->info; + regs->ARM_r2 = (unsigned long)&frame->sig.uc; + } + + return err; +} + +/* + * OK, we're invoking a handler + */ +static void handle_signal(struct ksignal *ksig, struct pt_regs *regs) +{ + sigset_t *oldset = sigmask_to_save(); + int ret; + + /* + * Perform fixup for the pre-signal frame. + */ + rseq_signal_deliver(ksig, regs); + + /* + * Set up the stack frame + */ + if (ksig->ka.sa.sa_flags & SA_SIGINFO) + ret = setup_rt_frame(ksig, oldset, regs); + else + ret = setup_frame(ksig, oldset, regs); + + /* + * Check that the resulting registers are actually sane. + */ + ret |= !valid_user_regs(regs); + + signal_setup_done(ret, ksig, 0); +} + +/* + * 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 int do_signal(struct pt_regs *regs, int syscall) +{ + unsigned int retval = 0, continue_addr = 0, restart_addr = 0; + struct ksignal ksig; + int restart = 0; + + /* + * If we were from a system call, check for system call restarting... + */ + if (syscall) { + continue_addr = regs->ARM_pc; + restart_addr = continue_addr - (thumb_mode(regs) ? 2 : 4); + retval = regs->ARM_r0; + + /* + * Prepare for system call restart. We do this here so that a + * debugger will see the already changed PSW. + */ + switch (retval) { + case -ERESTART_RESTARTBLOCK: + restart -= 2; + fallthrough; + case -ERESTARTNOHAND: + case -ERESTARTSYS: + case -ERESTARTNOINTR: + restart++; + regs->ARM_r0 = regs->ARM_ORIG_r0; + regs->ARM_pc = restart_addr; + break; + } + } + + /* + * Get the signal to deliver. When running under ptrace, at this + * point the debugger may change all our registers ... + */ + /* + * 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 (get_signal(&ksig)) { + /* handler */ + if (unlikely(restart) && regs->ARM_pc == restart_addr) { + if (retval == -ERESTARTNOHAND || + retval == -ERESTART_RESTARTBLOCK + || (retval == -ERESTARTSYS + && !(ksig.ka.sa.sa_flags & SA_RESTART))) { + regs->ARM_r0 = -EINTR; + regs->ARM_pc = continue_addr; + } + } + handle_signal(&ksig, regs); + } else { + /* no handler */ + restore_saved_sigmask(); + if (unlikely(restart) && regs->ARM_pc == restart_addr) { + regs->ARM_pc = continue_addr; + return restart; + } + } + return 0; +} + +asmlinkage int +do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall) +{ + /* + * 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 { + if (likely(thread_flags & _TIF_NEED_RESCHED)) { + schedule(); + } else { + if (unlikely(!user_mode(regs))) + return 0; + local_irq_enable(); + if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) { + int restart = do_signal(regs, syscall); + if (unlikely(restart)) { + /* + * Restart without handlers. + * Deal with it without leaving + * the kernel space. + */ + return restart; + } + syscall = 0; + } else if (thread_flags & _TIF_UPROBE) { + uprobe_notify_resume(regs); + } else { + resume_user_mode_work(regs); + } + } + local_irq_disable(); + thread_flags = read_thread_flags(); + } while (thread_flags & _TIF_WORK_MASK); + return 0; +} + +struct page *get_signal_page(void) +{ + unsigned long ptr; + unsigned offset; + struct page *page; + void *addr; + + page = alloc_pages(GFP_KERNEL, 0); + + if (!page) + return NULL; + + addr = page_address(page); + + /* Poison the entire page */ + memset32(addr, __opcode_to_mem_arm(0xe7fddef1), + PAGE_SIZE / sizeof(u32)); + + /* Give the signal return code some randomness */ + offset = 0x200 + (get_random_u16() & 0x7fc); + signal_return_offset = offset; + + /* Copy signal return handlers into the page */ + memcpy(addr + offset, sigreturn_codes, sizeof(sigreturn_codes)); + + /* Flush out all instructions in this page */ + ptr = (unsigned long)addr; + flush_icache_range(ptr, ptr + PAGE_SIZE); + + return page; +} + +#ifdef CONFIG_DEBUG_RSEQ +asmlinkage void do_rseq_syscall(struct pt_regs *regs) +{ + rseq_syscall(regs); +} +#endif + +/* + * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as + * changes likely come with new fields that should be added below. + */ +static_assert(NSIGILL == 11); +static_assert(NSIGFPE == 15); +static_assert(NSIGSEGV == 9); +static_assert(NSIGBUS == 5); +static_assert(NSIGTRAP == 6); +static_assert(NSIGCHLD == 6); +static_assert(NSIGSYS == 2); +static_assert(sizeof(siginfo_t) == 128); +static_assert(__alignof__(siginfo_t) == 4); +static_assert(offsetof(siginfo_t, si_signo) == 0x00); +static_assert(offsetof(siginfo_t, si_errno) == 0x04); +static_assert(offsetof(siginfo_t, si_code) == 0x08); +static_assert(offsetof(siginfo_t, si_pid) == 0x0c); +static_assert(offsetof(siginfo_t, si_uid) == 0x10); +static_assert(offsetof(siginfo_t, si_tid) == 0x0c); +static_assert(offsetof(siginfo_t, si_overrun) == 0x10); +static_assert(offsetof(siginfo_t, si_status) == 0x14); +static_assert(offsetof(siginfo_t, si_utime) == 0x18); +static_assert(offsetof(siginfo_t, si_stime) == 0x1c); +static_assert(offsetof(siginfo_t, si_value) == 0x14); +static_assert(offsetof(siginfo_t, si_int) == 0x14); +static_assert(offsetof(siginfo_t, si_ptr) == 0x14); +static_assert(offsetof(siginfo_t, si_addr) == 0x0c); +static_assert(offsetof(siginfo_t, si_addr_lsb) == 0x10); +static_assert(offsetof(siginfo_t, si_lower) == 0x14); +static_assert(offsetof(siginfo_t, si_upper) == 0x18); +static_assert(offsetof(siginfo_t, si_pkey) == 0x14); +static_assert(offsetof(siginfo_t, si_perf_data) == 0x10); +static_assert(offsetof(siginfo_t, si_perf_type) == 0x14); +static_assert(offsetof(siginfo_t, si_perf_flags) == 0x18); +static_assert(offsetof(siginfo_t, si_band) == 0x0c); +static_assert(offsetof(siginfo_t, si_fd) == 0x10); +static_assert(offsetof(siginfo_t, si_call_addr) == 0x0c); +static_assert(offsetof(siginfo_t, si_syscall) == 0x10); +static_assert(offsetof(siginfo_t, si_arch) == 0x14); |