diff options
Diffstat (limited to 'linux-user/host/riscv')
| -rw-r--r-- | linux-user/host/riscv/host-signal.h | 58 | ||||
| -rw-r--r-- | linux-user/host/riscv/hostdep.h | 34 | ||||
| -rw-r--r-- | linux-user/host/riscv/safe-syscall.inc.S | 77 |
3 files changed, 169 insertions, 0 deletions
diff --git a/linux-user/host/riscv/host-signal.h b/linux-user/host/riscv/host-signal.h new file mode 100644 index 0000000000..3b168cb58b --- /dev/null +++ b/linux-user/host/riscv/host-signal.h @@ -0,0 +1,58 @@ +/* + * host-signal.h: signal info dependent on the host architecture + * + * Copyright (c) 2003-2005 Fabrice Bellard + * Copyright (c) 2021 Linaro Limited + * + * This work is licensed under the terms of the GNU LGPL, version 2.1 or later. + * See the COPYING file in the top-level directory. + */ + +#ifndef RISCV_HOST_SIGNAL_H +#define RISCV_HOST_SIGNAL_H + +static inline uintptr_t host_signal_pc(ucontext_t *uc) +{ + return uc->uc_mcontext.__gregs[REG_PC]; +} + +static inline bool host_signal_write(siginfo_t *info, ucontext_t *uc) +{ + /* + * Detect store by reading the instruction at the program counter. + * Do not read more than 16 bits, because we have not yet determined + * the size of the instruction. + */ + const uint16_t *pinsn = (const uint16_t *)host_signal_pc(uc); + uint16_t insn = pinsn[0]; + + /* 16-bit instructions */ + switch (insn & 0xe003) { + case 0xa000: /* c.fsd */ + case 0xc000: /* c.sw */ + case 0xe000: /* c.sd (rv64) / c.fsw (rv32) */ + case 0xa002: /* c.fsdsp */ + case 0xc002: /* c.swsp */ + case 0xe002: /* c.sdsp (rv64) / c.fswsp (rv32) */ + return true; + } + + /* 32-bit instructions, major opcodes */ + switch (insn & 0x7f) { + case 0x23: /* store */ + case 0x27: /* store-fp */ + return true; + case 0x2f: /* amo */ + /* + * The AMO function code is in bits 25-31, unread as yet. + * The AMO functions are LR (read), SC (write), and the + * rest are all read-modify-write. + */ + insn = pinsn[1]; + return (insn >> 11) != 2; /* LR */ + } + + return false; +} + +#endif diff --git a/linux-user/host/riscv/hostdep.h b/linux-user/host/riscv/hostdep.h new file mode 100644 index 0000000000..2ba07456ae --- /dev/null +++ b/linux-user/host/riscv/hostdep.h @@ -0,0 +1,34 @@ +/* + * hostdep.h : things which are dependent on the host architecture + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +#ifndef RISCV_HOSTDEP_H +#define RISCV_HOSTDEP_H + +/* We have a safe-syscall.inc.S */ +#define HAVE_SAFE_SYSCALL + +#ifndef __ASSEMBLER__ + +/* These are defined by the safe-syscall.inc.S file */ +extern char safe_syscall_start[]; +extern char safe_syscall_end[]; + +/* Adjust the signal context to rewind out of safe-syscall if we're in it */ +static inline void rewind_if_in_safe_syscall(void *puc) +{ + ucontext_t *uc = puc; + unsigned long *pcreg = &uc->uc_mcontext.__gregs[REG_PC]; + + if (*pcreg > (uintptr_t)safe_syscall_start + && *pcreg < (uintptr_t)safe_syscall_end) { + *pcreg = (uintptr_t)safe_syscall_start; + } +} + +#endif /* __ASSEMBLER__ */ + +#endif diff --git a/linux-user/host/riscv/safe-syscall.inc.S b/linux-user/host/riscv/safe-syscall.inc.S new file mode 100644 index 0000000000..9ca3fbfd1e --- /dev/null +++ b/linux-user/host/riscv/safe-syscall.inc.S @@ -0,0 +1,77 @@ +/* + * safe-syscall.inc.S : host-specific assembly fragment + * to handle signals occurring at the same time as system calls. + * This is intended to be included by linux-user/safe-syscall.S + * + * Written by Richard Henderson <rth@twiddle.net> + * Copyright (C) 2018 Linaro, Inc. + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + + .global safe_syscall_base + .global safe_syscall_start + .global safe_syscall_end + .type safe_syscall_base, @function + .type safe_syscall_start, @function + .type safe_syscall_end, @function + + /* + * This is the entry point for making a system call. The calling + * convention here is that of a C varargs function with the + * first argument an 'int *' to the signal_pending flag, the + * second one the system call number (as a 'long'), and all further + * arguments being syscall arguments (also 'long'). + * We return a long which is the syscall's return value, which + * may be negative-errno on failure. Conversion to the + * -1-and-errno-set convention is done by the calling wrapper. + */ +safe_syscall_base: + .cfi_startproc + /* + * The syscall calling convention is nearly the same as C: + * we enter with a0 == *signal_pending + * a1 == syscall number + * a2 ... a7 == syscall arguments + * and return the result in a0 + * and the syscall instruction needs + * a7 == syscall number + * a0 ... a5 == syscall arguments + * and returns the result in a0 + * Shuffle everything around appropriately. + */ + mv t0, a0 /* signal_pending pointer */ + mv t1, a1 /* syscall number */ + mv a0, a2 /* syscall arguments */ + mv a1, a3 + mv a2, a4 + mv a3, a5 + mv a4, a6 + mv a5, a7 + mv a7, t1 + + /* + * This next sequence of code works in conjunction with the + * rewind_if_safe_syscall_function(). If a signal is taken + * and the interrupted PC is anywhere between 'safe_syscall_start' + * and 'safe_syscall_end' then we rewind it to 'safe_syscall_start'. + * The code sequence must therefore be able to cope with this, and + * the syscall instruction must be the final one in the sequence. + */ +safe_syscall_start: + /* If signal_pending is non-zero, don't do the call */ + lw t1, 0(t0) + bnez t1, 0f + scall +safe_syscall_end: + /* code path for having successfully executed the syscall */ + ret + +0: + /* code path when we didn't execute the syscall */ + li a0, -TARGET_ERESTARTSYS + ret + .cfi_endproc + + .size safe_syscall_base, .-safe_syscall_base |