1// SPDX-License-Identifier: GPL-2.0-or-later 2 3#include <linux/compat.h> 4#include <linux/signal.h> 5#include <linux/uaccess.h> 6#include <linux/syscalls.h> 7#include <linux/linkage.h> 8 9#include <asm/csr.h> 10#include <asm/signal32.h> 11#include <asm/switch_to.h> 12#include <asm/ucontext.h> 13#include <asm/vdso.h> 14 15#define COMPAT_DEBUG_SIG 0 16 17struct compat_sigcontext { 18 struct compat_user_regs_struct sc_regs; 19 union __riscv_fp_state sc_fpregs; 20}; 21 22struct compat_ucontext { 23 compat_ulong_t uc_flags; 24 struct compat_ucontext *uc_link; 25 compat_stack_t uc_stack; 26 sigset_t uc_sigmask; 27 /* There's some padding here to allow sigset_t to be expanded in the 28 * future. Though this is unlikely, other architectures put uc_sigmask 29 * at the end of this structure and explicitly state it can be 30 * expanded, so we didn't want to box ourselves in here. */ 31 __u8 __unused[1024 / 8 - sizeof(sigset_t)]; 32 /* We can't put uc_sigmask at the end of this structure because we need 33 * to be able to expand sigcontext in the future. For example, the 34 * vector ISA extension will almost certainly add ISA state. We want 35 * to ensure all user-visible ISA state can be saved and restored via a 36 * ucontext, so we're putting this at the end in order to allow for 37 * infinite extensibility. Since we know this will be extended and we 38 * assume sigset_t won't be extended an extreme amount, we're 39 * prioritizing this. */ 40 struct compat_sigcontext uc_mcontext; 41}; 42 43struct compat_rt_sigframe { 44 struct compat_siginfo info; 45 struct compat_ucontext uc; 46}; 47 48#ifdef CONFIG_FPU 49static long compat_restore_fp_state(struct pt_regs *regs, 50 union __riscv_fp_state __user *sc_fpregs) 51{ 52 long err; 53 struct __riscv_d_ext_state __user *state = &sc_fpregs->d; 54 size_t i; 55 56 err = __copy_from_user(¤t->thread.fstate, state, sizeof(*state)); 57 if (unlikely(err)) 58 return err; 59 60 fstate_restore(current, regs); 61 62 /* We support no other extension state at this time. */ 63 for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) { 64 u32 value; 65 66 err = __get_user(value, &sc_fpregs->q.reserved[i]); 67 if (unlikely(err)) 68 break; 69 if (value != 0) 70 return -EINVAL; 71 } 72 73 return err; 74} 75 76static long compat_save_fp_state(struct pt_regs *regs, 77 union __riscv_fp_state __user *sc_fpregs) 78{ 79 long err; 80 struct __riscv_d_ext_state __user *state = &sc_fpregs->d; 81 size_t i; 82 83 fstate_save(current, regs); 84 err = __copy_to_user(state, ¤t->thread.fstate, sizeof(*state)); 85 if (unlikely(err)) 86 return err; 87 88 /* We support no other extension state at this time. */ 89 for (i = 0; i < ARRAY_SIZE(sc_fpregs->q.reserved); i++) { 90 err = __put_user(0, &sc_fpregs->q.reserved[i]); 91 if (unlikely(err)) 92 break; 93 } 94 95 return err; 96} 97#else 98#define compat_save_fp_state(task, regs) (0) 99#define compat_restore_fp_state(task, regs) (0) 100#endif 101 102static long compat_restore_sigcontext(struct pt_regs *regs, 103 struct compat_sigcontext __user *sc) 104{ 105 long err; 106 struct compat_user_regs_struct cregs; 107 108 /* sc_regs is structured the same as the start of pt_regs */ 109 err = __copy_from_user(&cregs, &sc->sc_regs, sizeof(sc->sc_regs)); 110 111 cregs_to_regs(&cregs, regs); 112 113 /* Restore the floating-point state. */ 114 if (has_fpu()) 115 err |= compat_restore_fp_state(regs, &sc->sc_fpregs); 116 return err; 117} 118 119COMPAT_SYSCALL_DEFINE0(rt_sigreturn) 120{ 121 struct pt_regs *regs = current_pt_regs(); 122 struct compat_rt_sigframe __user *frame; 123 struct task_struct *task; 124 sigset_t set; 125 126 /* Always make any pending restarted system calls return -EINTR */ 127 current->restart_block.fn = do_no_restart_syscall; 128 129 frame = (struct compat_rt_sigframe __user *)regs->sp; 130 131 if (!access_ok(frame, sizeof(*frame))) 132 goto badframe; 133 134 if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set))) 135 goto badframe; 136 137 set_current_blocked(&set); 138 139 if (compat_restore_sigcontext(regs, &frame->uc.uc_mcontext)) 140 goto badframe; 141 142 if (compat_restore_altstack(&frame->uc.uc_stack)) 143 goto badframe; 144 145 return regs->a0; 146 147badframe: 148 task = current; 149 if (show_unhandled_signals) { 150 pr_info_ratelimited( 151 "%s[%d]: bad frame in %s: frame=%p pc=%p sp=%p\n", 152 task->comm, task_pid_nr(task), __func__, 153 frame, (void *)regs->epc, (void *)regs->sp); 154 } 155 force_sig(SIGSEGV); 156 return 0; 157} 158 159static long compat_setup_sigcontext(struct compat_rt_sigframe __user *frame, 160 struct pt_regs *regs) 161{ 162 struct compat_sigcontext __user *sc = &frame->uc.uc_mcontext; 163 struct compat_user_regs_struct cregs; 164 long err; 165 166 regs_to_cregs(&cregs, regs); 167 168 /* sc_regs is structured the same as the start of pt_regs */ 169 err = __copy_to_user(&sc->sc_regs, &cregs, sizeof(sc->sc_regs)); 170 /* Save the floating-point state. */ 171 if (has_fpu()) 172 err |= compat_save_fp_state(regs, &sc->sc_fpregs); 173 return err; 174} 175 176static inline void __user *compat_get_sigframe(struct ksignal *ksig, 177 struct pt_regs *regs, size_t framesize) 178{ 179 unsigned long sp; 180 /* Default to using normal stack */ 181 sp = regs->sp; 182 183 /* 184 * If we are on the alternate signal stack and would overflow it, don't. 185 * Return an always-bogus address instead so we will die with SIGSEGV. 186 */ 187 if (on_sig_stack(sp) && !likely(on_sig_stack(sp - framesize))) 188 return (void __user __force *)(-1UL); 189 190 /* This is the X/Open sanctioned signal stack switching. */ 191 sp = sigsp(sp, ksig) - framesize; 192 193 /* Align the stack frame. */ 194 sp &= ~0xfUL; 195 196 return (void __user *)sp; 197} 198 199int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set, 200 struct pt_regs *regs) 201{ 202 struct compat_rt_sigframe __user *frame; 203 long err = 0; 204 205 frame = compat_get_sigframe(ksig, regs, sizeof(*frame)); 206 if (!access_ok(frame, sizeof(*frame))) 207 return -EFAULT; 208 209 err |= copy_siginfo_to_user32(&frame->info, &ksig->info); 210 211 /* Create the ucontext. */ 212 err |= __put_user(0, &frame->uc.uc_flags); 213 err |= __put_user(NULL, &frame->uc.uc_link); 214 err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp); 215 err |= compat_setup_sigcontext(frame, regs); 216 err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set)); 217 if (err) 218 return -EFAULT; 219 220 regs->ra = (unsigned long)COMPAT_VDSO_SYMBOL( 221 current->mm->context.vdso, rt_sigreturn); 222 223 /* 224 * Set up registers for signal handler. 225 * Registers that we don't modify keep the value they had from 226 * user-space at the time we took the signal. 227 * We always pass siginfo and mcontext, regardless of SA_SIGINFO, 228 * since some things rely on this (e.g. glibc's debug/segfault.c). 229 */ 230 regs->epc = (unsigned long)ksig->ka.sa.sa_handler; 231 regs->sp = (unsigned long)frame; 232 regs->a0 = ksig->sig; /* a0: signal number */ 233 regs->a1 = (unsigned long)(&frame->info); /* a1: siginfo pointer */ 234 regs->a2 = (unsigned long)(&frame->uc); /* a2: ucontext pointer */ 235 236#if COMPAT_DEBUG_SIG 237 pr_info("SIG deliver (%s:%d): sig=%d pc=%p ra=%p sp=%p\n", 238 current->comm, task_pid_nr(current), ksig->sig, 239 (void *)regs->epc, (void *)regs->ra, frame); 240#endif 241 242 return 0; 243} 244