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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /arch/um/os-Linux/signal.c | |
parent | Initial commit. (diff) | |
download | linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | arch/um/os-Linux/signal.c | 419 |
1 files changed, 419 insertions, 0 deletions
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c new file mode 100644 index 000000000..24a403a70 --- /dev/null +++ b/arch/um/os-Linux/signal.c @@ -0,0 +1,419 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk}) + * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de) + * Copyright (C) 2004 PathScale, Inc + * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com) + */ + +#include <stdlib.h> +#include <stdarg.h> +#include <errno.h> +#include <signal.h> +#include <string.h> +#include <strings.h> +#include <as-layout.h> +#include <kern_util.h> +#include <os.h> +#include <sysdep/mcontext.h> +#include <um_malloc.h> +#include <sys/ucontext.h> +#include <timetravel.h> + +void (*sig_info[NSIG])(int, struct siginfo *, struct uml_pt_regs *) = { + [SIGTRAP] = relay_signal, + [SIGFPE] = relay_signal, + [SIGILL] = relay_signal, + [SIGWINCH] = winch, + [SIGBUS] = bus_handler, + [SIGSEGV] = segv_handler, + [SIGIO] = sigio_handler, +}; + +static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc) +{ + struct uml_pt_regs r; + int save_errno = errno; + + r.is_user = 0; + if (sig == SIGSEGV) { + /* For segfaults, we want the data from the sigcontext. */ + get_regs_from_mc(&r, mc); + GET_FAULTINFO_FROM_MC(r.faultinfo, mc); + } + + /* enable signals if sig isn't IRQ signal */ + if ((sig != SIGIO) && (sig != SIGWINCH)) + unblock_signals_trace(); + + (*sig_info[sig])(sig, si, &r); + + errno = save_errno; +} + +/* + * These are the asynchronous signals. SIGPROF is excluded because we want to + * be able to profile all of UML, not just the non-critical sections. If + * profiling is not thread-safe, then that is not my problem. We can disable + * profiling when SMP is enabled in that case. + */ +#define SIGIO_BIT 0 +#define SIGIO_MASK (1 << SIGIO_BIT) + +#define SIGALRM_BIT 1 +#define SIGALRM_MASK (1 << SIGALRM_BIT) + +int signals_enabled; +#ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT +static int signals_blocked; +#else +#define signals_blocked 0 +#endif +static unsigned int signals_pending; +static unsigned int signals_active = 0; + +void sig_handler(int sig, struct siginfo *si, mcontext_t *mc) +{ + int enabled = signals_enabled; + + if ((signals_blocked || !enabled) && (sig == SIGIO)) { + /* + * In TT_MODE_EXTERNAL, need to still call time-travel + * handlers unless signals are also blocked for the + * external time message processing. This will mark + * signals_pending by itself (only if necessary.) + */ + if (!signals_blocked && time_travel_mode == TT_MODE_EXTERNAL) + sigio_run_timetravel_handlers(); + else + signals_pending |= SIGIO_MASK; + return; + } + + block_signals_trace(); + + sig_handler_common(sig, si, mc); + + um_set_signals_trace(enabled); +} + +static void timer_real_alarm_handler(mcontext_t *mc) +{ + struct uml_pt_regs regs; + + if (mc != NULL) + get_regs_from_mc(®s, mc); + else + memset(®s, 0, sizeof(regs)); + timer_handler(SIGALRM, NULL, ®s); +} + +void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc) +{ + int enabled; + + enabled = signals_enabled; + if (!signals_enabled) { + signals_pending |= SIGALRM_MASK; + return; + } + + block_signals_trace(); + + signals_active |= SIGALRM_MASK; + + timer_real_alarm_handler(mc); + + signals_active &= ~SIGALRM_MASK; + + um_set_signals_trace(enabled); +} + +void deliver_alarm(void) { + timer_alarm_handler(SIGALRM, NULL, NULL); +} + +void timer_set_signal_handler(void) +{ + set_handler(SIGALRM); +} + +void set_sigstack(void *sig_stack, int size) +{ + stack_t stack = { + .ss_flags = 0, + .ss_sp = sig_stack, + .ss_size = size + }; + + if (sigaltstack(&stack, NULL) != 0) + panic("enabling signal stack failed, errno = %d\n", errno); +} + +static void sigusr1_handler(int sig, struct siginfo *unused_si, mcontext_t *mc) +{ + uml_pm_wake(); +} + +void register_pm_wake_signal(void) +{ + set_handler(SIGUSR1); +} + +static void (*handlers[_NSIG])(int sig, struct siginfo *si, mcontext_t *mc) = { + [SIGSEGV] = sig_handler, + [SIGBUS] = sig_handler, + [SIGILL] = sig_handler, + [SIGFPE] = sig_handler, + [SIGTRAP] = sig_handler, + + [SIGIO] = sig_handler, + [SIGWINCH] = sig_handler, + [SIGALRM] = timer_alarm_handler, + + [SIGUSR1] = sigusr1_handler, +}; + +static void hard_handler(int sig, siginfo_t *si, void *p) +{ + ucontext_t *uc = p; + mcontext_t *mc = &uc->uc_mcontext; + unsigned long pending = 1UL << sig; + + do { + int nested, bail; + + /* + * pending comes back with one bit set for each + * interrupt that arrived while setting up the stack, + * plus a bit for this interrupt, plus the zero bit is + * set if this is a nested interrupt. + * If bail is true, then we interrupted another + * handler setting up the stack. In this case, we + * have to return, and the upper handler will deal + * with this interrupt. + */ + bail = to_irq_stack(&pending); + if (bail) + return; + + nested = pending & 1; + pending &= ~1; + + while ((sig = ffs(pending)) != 0){ + sig--; + pending &= ~(1 << sig); + (*handlers[sig])(sig, (struct siginfo *)si, mc); + } + + /* + * Again, pending comes back with a mask of signals + * that arrived while tearing down the stack. If this + * is non-zero, we just go back, set up the stack + * again, and handle the new interrupts. + */ + if (!nested) + pending = from_irq_stack(nested); + } while (pending); +} + +void set_handler(int sig) +{ + struct sigaction action; + int flags = SA_SIGINFO | SA_ONSTACK; + sigset_t sig_mask; + + action.sa_sigaction = hard_handler; + + /* block irq ones */ + sigemptyset(&action.sa_mask); + sigaddset(&action.sa_mask, SIGIO); + sigaddset(&action.sa_mask, SIGWINCH); + sigaddset(&action.sa_mask, SIGALRM); + + if (sig == SIGSEGV) + flags |= SA_NODEFER; + + if (sigismember(&action.sa_mask, sig)) + flags |= SA_RESTART; /* if it's an irq signal */ + + action.sa_flags = flags; + action.sa_restorer = NULL; + if (sigaction(sig, &action, NULL) < 0) + panic("sigaction failed - errno = %d\n", errno); + + sigemptyset(&sig_mask); + sigaddset(&sig_mask, sig); + if (sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0) + panic("sigprocmask failed - errno = %d\n", errno); +} + +void send_sigio_to_self(void) +{ + kill(os_getpid(), SIGIO); +} + +int change_sig(int signal, int on) +{ + sigset_t sigset; + + sigemptyset(&sigset); + sigaddset(&sigset, signal); + if (sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, NULL) < 0) + return -errno; + + return 0; +} + +void block_signals(void) +{ + signals_enabled = 0; + /* + * This must return with signals disabled, so this barrier + * ensures that writes are flushed out before the return. + * This might matter if gcc figures out how to inline this and + * decides to shuffle this code into the caller. + */ + barrier(); +} + +void unblock_signals(void) +{ + int save_pending; + + if (signals_enabled == 1) + return; + + signals_enabled = 1; +#ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT + deliver_time_travel_irqs(); +#endif + + /* + * We loop because the IRQ handler returns with interrupts off. So, + * interrupts may have arrived and we need to re-enable them and + * recheck signals_pending. + */ + while (1) { + /* + * Save and reset save_pending after enabling signals. This + * way, signals_pending won't be changed while we're reading it. + * + * Setting signals_enabled and reading signals_pending must + * happen in this order, so have the barrier here. + */ + barrier(); + + save_pending = signals_pending; + if (save_pending == 0) + return; + + signals_pending = 0; + + /* + * We have pending interrupts, so disable signals, as the + * handlers expect them off when they are called. They will + * be enabled again above. We need to trace this, as we're + * expected to be enabling interrupts already, but any more + * tracing that happens inside the handlers we call for the + * pending signals will mess up the tracing state. + */ + signals_enabled = 0; + um_trace_signals_off(); + + /* + * Deal with SIGIO first because the alarm handler might + * schedule, leaving the pending SIGIO stranded until we come + * back here. + * + * SIGIO's handler doesn't use siginfo or mcontext, + * so they can be NULL. + */ + if (save_pending & SIGIO_MASK) + sig_handler_common(SIGIO, NULL, NULL); + + /* Do not reenter the handler */ + + if ((save_pending & SIGALRM_MASK) && (!(signals_active & SIGALRM_MASK))) + timer_real_alarm_handler(NULL); + + /* Rerun the loop only if there is still pending SIGIO and not in TIMER handler */ + + if (!(signals_pending & SIGIO_MASK) && (signals_active & SIGALRM_MASK)) + return; + + /* Re-enable signals and trace that we're doing so. */ + um_trace_signals_on(); + signals_enabled = 1; + } +} + +int um_set_signals(int enable) +{ + int ret; + if (signals_enabled == enable) + return enable; + + ret = signals_enabled; + if (enable) + unblock_signals(); + else block_signals(); + + return ret; +} + +int um_set_signals_trace(int enable) +{ + int ret; + if (signals_enabled == enable) + return enable; + + ret = signals_enabled; + if (enable) + unblock_signals_trace(); + else + block_signals_trace(); + + return ret; +} + +#ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT +void mark_sigio_pending(void) +{ + signals_pending |= SIGIO_MASK; +} + +void block_signals_hard(void) +{ + if (signals_blocked) + return; + signals_blocked = 1; + barrier(); +} + +void unblock_signals_hard(void) +{ + if (!signals_blocked) + return; + /* Must be set to 0 before we check the pending bits etc. */ + signals_blocked = 0; + barrier(); + + if (signals_pending && signals_enabled) { + /* this is a bit inefficient, but that's not really important */ + block_signals(); + unblock_signals(); + } else if (signals_pending & SIGIO_MASK) { + /* we need to run time-travel handlers even if not enabled */ + sigio_run_timetravel_handlers(); + } +} +#endif + +int os_is_signal_stack(void) +{ + stack_t ss; + sigaltstack(NULL, &ss); + + return ss.ss_flags & SS_ONSTACK; +} |