From e6037d04c58284285726721d0d4741e1386594e9 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Thu, 16 Sep 2021 14:44:17 -0700 Subject: [PATCH] linux-user: Reorg handling for SIGSEGV MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add stub host-signal.h for all linux-user hosts. Add new code replacing cpu_signal_handler. Full migration will happen one host at a time. Reviewed-by: Warner Losh Reviewed-by: Philippe Mathieu-Daudé Acked-by: Alistair Francis Signed-off-by: Richard Henderson --- linux-user/host/aarch64/host-signal.h | 1 + linux-user/host/arm/host-signal.h | 1 + linux-user/host/i386/host-signal.h | 1 + linux-user/host/mips/host-signal.h | 1 + linux-user/host/ppc/host-signal.h | 1 + linux-user/host/ppc64/host-signal.h | 1 + linux-user/host/riscv/host-signal.h | 1 + linux-user/host/s390/host-signal.h | 1 + linux-user/host/s390x/host-signal.h | 1 + linux-user/host/sparc/host-signal.h | 1 + linux-user/host/sparc64/host-signal.h | 1 + linux-user/host/x32/host-signal.h | 1 + linux-user/host/x86_64/host-signal.h | 1 + linux-user/signal.c | 109 ++++++++++++++++++++++---- 14 files changed, 106 insertions(+), 16 deletions(-) create mode 100644 linux-user/host/aarch64/host-signal.h create mode 100644 linux-user/host/arm/host-signal.h create mode 100644 linux-user/host/i386/host-signal.h create mode 100644 linux-user/host/mips/host-signal.h create mode 100644 linux-user/host/ppc/host-signal.h create mode 100644 linux-user/host/ppc64/host-signal.h create mode 100644 linux-user/host/riscv/host-signal.h create mode 100644 linux-user/host/s390/host-signal.h create mode 100644 linux-user/host/s390x/host-signal.h create mode 100644 linux-user/host/sparc/host-signal.h create mode 100644 linux-user/host/sparc64/host-signal.h create mode 100644 linux-user/host/x32/host-signal.h create mode 100644 linux-user/host/x86_64/host-signal.h diff --git a/linux-user/host/aarch64/host-signal.h b/linux-user/host/aarch64/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/aarch64/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/arm/host-signal.h b/linux-user/host/arm/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/arm/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/i386/host-signal.h b/linux-user/host/i386/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/i386/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/mips/host-signal.h b/linux-user/host/mips/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/mips/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/ppc/host-signal.h b/linux-user/host/ppc/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/ppc/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/ppc64/host-signal.h b/linux-user/host/ppc64/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/ppc64/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/riscv/host-signal.h b/linux-user/host/riscv/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/riscv/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/s390/host-signal.h b/linux-user/host/s390/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/s390/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/s390x/host-signal.h b/linux-user/host/s390x/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/s390x/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/sparc/host-signal.h b/linux-user/host/sparc/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/sparc/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/sparc64/host-signal.h b/linux-user/host/sparc64/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/sparc64/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/x32/host-signal.h b/linux-user/host/x32/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/x32/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/host/x86_64/host-signal.h b/linux-user/host/x86_64/host-signal.h new file mode 100644 index 0000000000..f4b4d65031 --- /dev/null +++ b/linux-user/host/x86_64/host-signal.h @@ -0,0 +1 @@ +#define HOST_SIGNAL_PLACEHOLDER diff --git a/linux-user/signal.c b/linux-user/signal.c index 14d8fdfde1..6900acb122 100644 --- a/linux-user/signal.c +++ b/linux-user/signal.c @@ -19,6 +19,7 @@ #include "qemu/osdep.h" #include "qemu/bitops.h" #include "exec/gdbstub.h" +#include "hw/core/tcg-cpu-ops.h" #include #include @@ -29,6 +30,7 @@ #include "loader.h" #include "trace.h" #include "signal-common.h" +#include "host-signal.h" static struct target_sigaction sigact_table[TARGET_NSIG]; @@ -769,41 +771,116 @@ static inline void rewind_if_in_safe_syscall(void *puc) } #endif -static void host_signal_handler(int host_signum, siginfo_t *info, - void *puc) +static void host_signal_handler(int host_sig, siginfo_t *info, void *puc) { CPUArchState *env = thread_cpu->env_ptr; CPUState *cpu = env_cpu(env); TaskState *ts = cpu->opaque; - - int sig; target_siginfo_t tinfo; ucontext_t *uc = puc; struct emulated_sigtable *k; + int guest_sig; +#ifdef HOST_SIGNAL_PLACEHOLDER /* the CPU emulator uses some host signals to detect exceptions, we forward to it some signals */ - if ((host_signum == SIGSEGV || host_signum == SIGBUS) + if ((host_sig == SIGSEGV || host_sig == SIGBUS) && info->si_code > 0) { - if (cpu_signal_handler(host_signum, info, puc)) + if (cpu_signal_handler(host_sig, info, puc)) { return; + } } +#else + uintptr_t pc = 0; + bool sync_sig = false; + + /* + * Non-spoofed SIGSEGV and SIGBUS are synchronous, and need special + * handling wrt signal blocking and unwinding. + */ + if ((host_sig == SIGSEGV || host_sig == SIGBUS) && info->si_code > 0) { + MMUAccessType access_type; + uintptr_t host_addr; + abi_ptr guest_addr; + bool is_write; + + host_addr = (uintptr_t)info->si_addr; + + /* + * Convert forcefully to guest address space: addresses outside + * reserved_va are still valid to report via SEGV_MAPERR. + */ + guest_addr = h2g_nocheck(host_addr); + + pc = host_signal_pc(uc); + is_write = host_signal_write(info, uc); + access_type = adjust_signal_pc(&pc, is_write); + + if (host_sig == SIGSEGV) { + const struct TCGCPUOps *tcg_ops; + + if (info->si_code == SEGV_ACCERR && h2g_valid(host_addr)) { + /* If this was a write to a TB protected page, restart. */ + if (is_write && + handle_sigsegv_accerr_write(cpu, &uc->uc_sigmask, + pc, guest_addr)) { + return; + } + + /* + * With reserved_va, the whole address space is PROT_NONE, + * which means that we may get ACCERR when we want MAPERR. + */ + if (page_get_flags(guest_addr) & PAGE_VALID) { + /* maperr = false; */ + } else { + info->si_code = SEGV_MAPERR; + } + } + + sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL); + + tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops; + tcg_ops->tlb_fill(cpu, guest_addr, 0, access_type, + MMU_USER_IDX, false, pc); + g_assert_not_reached(); + } else { + sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL); + } + + sync_sig = true; + } +#endif /* get target signal number */ - sig = host_to_target_signal(host_signum); - if (sig < 1 || sig > TARGET_NSIG) + guest_sig = host_to_target_signal(host_sig); + if (guest_sig < 1 || guest_sig > TARGET_NSIG) { return; - trace_user_host_signal(env, host_signum, sig); + } + trace_user_host_signal(env, host_sig, guest_sig); + + host_to_target_siginfo_noswap(&tinfo, info); + k = &ts->sigtab[guest_sig - 1]; + k->info = tinfo; + k->pending = guest_sig; + ts->signal_pending = 1; + +#ifndef HOST_SIGNAL_PLACEHOLDER + /* + * For synchronous signals, unwind the cpu state to the faulting + * insn and then exit back to the main loop so that the signal + * is delivered immediately. + */ + if (sync_sig) { + cpu->exception_index = EXCP_INTERRUPT; + cpu_loop_exit_restore(cpu, pc); + } +#endif rewind_if_in_safe_syscall(puc); - host_to_target_siginfo_noswap(&tinfo, info); - k = &ts->sigtab[sig - 1]; - k->info = tinfo; - k->pending = sig; - ts->signal_pending = 1; - - /* Block host signals until target signal handler entered. We + /* + * Block host signals until target signal handler entered. We * can't block SIGSEGV or SIGBUS while we're executing guest * code in case the guest code provokes one in the window between * now and it getting out to the main loop. Signals will be