From 72d2bbf9ff3e1edf5d57b53149eeaa36f19fb891 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Fri, 17 Sep 2021 17:32:56 -0700 Subject: linux-user: Add cpu_loop_exit_sigsegv MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This is a new interface to be provided by the os emulator for raising SIGSEGV on fault. Use the new record_sigsegv target hook. Reviewed by: Warner Losh Reviewed-by: Philippe Mathieu-Daudé Signed-off-by: Richard Henderson --- accel/tcg/user-exec.c | 33 ++++++++++++++++++--------------- include/exec/exec-all.h | 15 +++++++++++++++ linux-user/signal.c | 30 ++++++++++++++++++++++-------- 3 files changed, 55 insertions(+), 23 deletions(-) diff --git a/accel/tcg/user-exec.c b/accel/tcg/user-exec.c index a0cba61..c4f6990 100644 --- a/accel/tcg/user-exec.c +++ b/accel/tcg/user-exec.c @@ -141,35 +141,38 @@ static int probe_access_internal(CPUArchState *env, target_ulong addr, int fault_size, MMUAccessType access_type, bool nonfault, uintptr_t ra) { - int flags; + int acc_flag; + bool maperr; switch (access_type) { case MMU_DATA_STORE: - flags = PAGE_WRITE; + acc_flag = PAGE_WRITE_ORG; break; case MMU_DATA_LOAD: - flags = PAGE_READ; + acc_flag = PAGE_READ; break; case MMU_INST_FETCH: - flags = PAGE_EXEC; + acc_flag = PAGE_EXEC; break; default: g_assert_not_reached(); } - if (!guest_addr_valid_untagged(addr) || - page_check_range(addr, 1, flags) < 0) { - if (nonfault) { - return TLB_INVALID_MASK; - } else { - CPUState *cpu = env_cpu(env); - CPUClass *cc = CPU_GET_CLASS(cpu); - cc->tcg_ops->tlb_fill(cpu, addr, fault_size, access_type, - MMU_USER_IDX, false, ra); - g_assert_not_reached(); + if (guest_addr_valid_untagged(addr)) { + int page_flags = page_get_flags(addr); + if (page_flags & acc_flag) { + return 0; /* success */ } + maperr = !(page_flags & PAGE_VALID); + } else { + maperr = true; + } + + if (nonfault) { + return TLB_INVALID_MASK; } - return 0; + + cpu_loop_exit_sigsegv(env_cpu(env), addr, access_type, maperr, ra); } int probe_access_flags(CPUArchState *env, target_ulong addr, diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h index 5dd663c..f745785 100644 --- a/include/exec/exec-all.h +++ b/include/exec/exec-all.h @@ -685,6 +685,21 @@ MMUAccessType adjust_signal_pc(uintptr_t *pc, bool is_write); bool handle_sigsegv_accerr_write(CPUState *cpu, sigset_t *old_set, uintptr_t host_pc, abi_ptr guest_addr); +/** + * cpu_loop_exit_sigsegv: + * @cpu: the cpu context + * @addr: the guest address of the fault + * @access_type: access was read/write/execute + * @maperr: true for invalid page, false for permission fault + * @ra: host pc for unwinding + * + * Use the TCGCPUOps hook to record cpu state, do guest operating system + * specific things to raise SIGSEGV, and jump to the main cpu loop. + */ +void QEMU_NORETURN cpu_loop_exit_sigsegv(CPUState *cpu, target_ulong addr, + MMUAccessType access_type, + bool maperr, uintptr_t ra); + #else static inline void mmap_lock(void) {} static inline void mmap_unlock(void) {} diff --git a/linux-user/signal.c b/linux-user/signal.c index b816678..1359837 100644 --- a/linux-user/signal.c +++ b/linux-user/signal.c @@ -688,9 +688,27 @@ void force_sigsegv(int oldsig) } force_sig(TARGET_SIGSEGV); } - #endif +void cpu_loop_exit_sigsegv(CPUState *cpu, target_ulong addr, + MMUAccessType access_type, bool maperr, uintptr_t ra) +{ + const struct TCGCPUOps *tcg_ops = CPU_GET_CLASS(cpu)->tcg_ops; + + if (tcg_ops->record_sigsegv) { + tcg_ops->record_sigsegv(cpu, addr, access_type, maperr, ra); + } else if (tcg_ops->tlb_fill) { + tcg_ops->tlb_fill(cpu, addr, 0, access_type, MMU_USER_IDX, false, ra); + g_assert_not_reached(); + } + + force_sig_fault(TARGET_SIGSEGV, + maperr ? TARGET_SEGV_MAPERR : TARGET_SEGV_ACCERR, + addr); + cpu->exception_index = EXCP_INTERRUPT; + cpu_loop_exit_restore(cpu, ra); +} + /* abort execution with signal */ static void QEMU_NORETURN dump_core_and_abort(int target_sig) { @@ -806,7 +824,7 @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc) access_type = adjust_signal_pc(&pc, is_write); if (host_sig == SIGSEGV) { - const struct TCGCPUOps *tcg_ops; + bool maperr = true; if (info->si_code == SEGV_ACCERR && h2g_valid(host_addr)) { /* If this was a write to a TB protected page, restart. */ @@ -821,18 +839,14 @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc) * which means that we may get ACCERR when we want MAPERR. */ if (page_get_flags(guest_addr) & PAGE_VALID) { - /* maperr = false; */ + 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(); + cpu_loop_exit_sigsegv(cpu, guest_addr, access_type, maperr, pc); } else { sigprocmask(SIG_SETMASK, &uc->uc_sigmask, NULL); } -- cgit v1.1