From 46f4f76d332d8c2b4eb24c8e6f91ac8bdc205733 Mon Sep 17 00:00:00 2001 From: Warner Losh Date: Sat, 8 Jan 2022 21:40:28 -0700 Subject: [PATCH] bsd-user/signal.c: setup_frame setup_frame sets up a signalled stack frame. Associated routines to extract the pointer to the stack frame and to support alternate stacks. Signed-off-by: Stacey Son Signed-off-by: Kyle Evans Signed-off-by: Warner Losh Reviewed-by: Richard Henderson --- bsd-user/main.c | 5 ++++ bsd-user/qemu.h | 3 +- bsd-user/signal.c | 83 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 90 insertions(+), 1 deletion(-) diff --git a/bsd-user/main.c b/bsd-user/main.c index 29cf4e1569..f1d58e905e 100644 --- a/bsd-user/main.c +++ b/bsd-user/main.c @@ -217,6 +217,11 @@ void qemu_cpu_kick(CPUState *cpu) /* Assumes contents are already zeroed. */ static void init_task_state(TaskState *ts) { + ts->sigaltstack_used = (struct target_sigaltstack) { + .ss_sp = 0, + .ss_size = 0, + .ss_flags = TARGET_SS_DISABLE, + }; } void gemu_log(const char *fmt, ...) diff --git a/bsd-user/qemu.h b/bsd-user/qemu.h index 1648a509b9..de20650a00 100644 --- a/bsd-user/qemu.h +++ b/bsd-user/qemu.h @@ -107,7 +107,8 @@ typedef struct TaskState { */ sigset_t signal_mask; - uint8_t stack[]; + /* This thread's sigaltstack, if it has one */ + struct target_sigaltstack sigaltstack_used; } __attribute__((aligned(16))) TaskState; void stop_all_tasks(void); diff --git a/bsd-user/signal.c b/bsd-user/signal.c index 84dafa4e9f..dbc1373607 100644 --- a/bsd-user/signal.c +++ b/bsd-user/signal.c @@ -35,6 +35,16 @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc); static void target_to_host_sigset_internal(sigset_t *d, const target_sigset_t *s); +static inline int on_sig_stack(TaskState *ts, unsigned long sp) +{ + return sp - ts->sigaltstack_used.ss_sp < ts->sigaltstack_used.ss_size; +} + +static inline int sas_ss_flags(TaskState *ts, unsigned long sp) +{ + return ts->sigaltstack_used.ss_size == 0 ? SS_DISABLE : + on_sig_stack(ts, sp) ? SS_ONSTACK : 0; +} /* * The BSD ABIs use the same singal numbers across all the CPU architectures, so @@ -491,6 +501,79 @@ static void host_signal_handler(int host_sig, siginfo_t *info, void *puc) cpu_exit(thread_cpu); } +static inline abi_ulong get_sigframe(struct target_sigaction *ka, + CPUArchState *env, size_t frame_size) +{ + TaskState *ts = (TaskState *)thread_cpu->opaque; + abi_ulong sp; + + /* Use default user stack */ + sp = get_sp_from_cpustate(env); + + if ((ka->sa_flags & TARGET_SA_ONSTACK) && sas_ss_flags(ts, sp) == 0) { + sp = ts->sigaltstack_used.ss_sp + ts->sigaltstack_used.ss_size; + } + +/* TODO: make this a target_arch function / define */ +#if defined(TARGET_ARM) + return (sp - frame_size) & ~7; +#elif defined(TARGET_AARCH64) + return (sp - frame_size) & ~15; +#else + return sp - frame_size; +#endif +} + +/* compare to $M/$M/exec_machdep.c sendsig and sys/kern/kern_sig.c sigexit */ + +static void setup_frame(int sig, int code, struct target_sigaction *ka, + target_sigset_t *set, target_siginfo_t *tinfo, CPUArchState *env) +{ + struct target_sigframe *frame; + abi_ulong frame_addr; + int i; + + frame_addr = get_sigframe(ka, env, sizeof(*frame)); + trace_user_setup_frame(env, frame_addr); + if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) { + unlock_user_struct(frame, frame_addr, 1); + dump_core_and_abort(TARGET_SIGILL); + return; + } + + memset(frame, 0, sizeof(*frame)); + setup_sigframe_arch(env, frame_addr, frame, 0); + + for (i = 0; i < TARGET_NSIG_WORDS; i++) { + __put_user(set->__bits[i], &frame->sf_uc.uc_sigmask.__bits[i]); + } + + if (tinfo) { + frame->sf_si.si_signo = tinfo->si_signo; + frame->sf_si.si_errno = tinfo->si_errno; + frame->sf_si.si_code = tinfo->si_code; + frame->sf_si.si_pid = tinfo->si_pid; + frame->sf_si.si_uid = tinfo->si_uid; + frame->sf_si.si_status = tinfo->si_status; + frame->sf_si.si_addr = tinfo->si_addr; + /* see host_to_target_siginfo_noswap() for more details */ + frame->sf_si.si_value.sival_ptr = tinfo->si_value.sival_ptr; + /* + * At this point, whatever is in the _reason union is complete + * and in target order, so just copy the whole thing over, even + * if it's too large for this specific signal. + * host_to_target_siginfo_noswap() and tswap_siginfo() have ensured + * that's so. + */ + memcpy(&frame->sf_si._reason, &tinfo->_reason, + sizeof(tinfo->_reason)); + } + + set_sigtramp_args(env, sig, frame, frame_addr, ka); + + unlock_user_struct(frame, frame_addr, 1); +} + void signal_init(void) { TaskState *ts = (TaskState *)thread_cpu->opaque; -- 2.11.0