diff options
Diffstat (limited to '')
| -rw-r--r-- | arch/um/os-Linux/drivers/ethertap_kern.c | 2 | ||||
| -rw-r--r-- | arch/um/os-Linux/drivers/tuntap_kern.c | 2 | ||||
| -rw-r--r-- | arch/um/os-Linux/elf_aux.c | 1 | ||||
| -rw-r--r-- | arch/um/os-Linux/internal.h | 20 | ||||
| -rw-r--r-- | arch/um/os-Linux/main.c | 8 | ||||
| -rw-r--r-- | arch/um/os-Linux/mem.c | 1 | ||||
| -rw-r--r-- | arch/um/os-Linux/signal.c | 122 | ||||
| -rw-r--r-- | arch/um/os-Linux/skas/mem.c | 3 | ||||
| -rw-r--r-- | arch/um/os-Linux/skas/process.c | 1 | ||||
| -rw-r--r-- | arch/um/os-Linux/start_up.c | 4 |
10 files changed, 134 insertions, 30 deletions
diff --git a/arch/um/os-Linux/drivers/ethertap_kern.c b/arch/um/os-Linux/drivers/ethertap_kern.c index 3182e759d8..5e5ee40680 100644 --- a/arch/um/os-Linux/drivers/ethertap_kern.c +++ b/arch/um/os-Linux/drivers/ethertap_kern.c @@ -63,7 +63,7 @@ const struct net_kern_info ethertap_kern_info = { .write = etap_write, }; -int ethertap_setup(char *str, char **mac_out, void *data) +static int ethertap_setup(char *str, char **mac_out, void *data) { struct ethertap_init *init = data; diff --git a/arch/um/os-Linux/drivers/tuntap_kern.c b/arch/um/os-Linux/drivers/tuntap_kern.c index adcb6717be..ff022d9cf0 100644 --- a/arch/um/os-Linux/drivers/tuntap_kern.c +++ b/arch/um/os-Linux/drivers/tuntap_kern.c @@ -53,7 +53,7 @@ const struct net_kern_info tuntap_kern_info = { .write = tuntap_write, }; -int tuntap_setup(char *str, char **mac_out, void *data) +static int tuntap_setup(char *str, char **mac_out, void *data) { struct tuntap_init *init = data; diff --git a/arch/um/os-Linux/elf_aux.c b/arch/um/os-Linux/elf_aux.c index 344ac403fb..0a0f91cf4d 100644 --- a/arch/um/os-Linux/elf_aux.c +++ b/arch/um/os-Linux/elf_aux.c @@ -13,6 +13,7 @@ #include <init.h> #include <elf_user.h> #include <mem_user.h> +#include "internal.h" typedef Elf32_auxv_t elf_auxv_t; diff --git a/arch/um/os-Linux/internal.h b/arch/um/os-Linux/internal.h new file mode 100644 index 0000000000..317fca190c --- /dev/null +++ b/arch/um/os-Linux/internal.h @@ -0,0 +1,20 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __UM_OS_LINUX_INTERNAL_H +#define __UM_OS_LINUX_INTERNAL_H + +/* + * elf_aux.c + */ +void scan_elf_aux(char **envp); + +/* + * mem.c + */ +void check_tmpexec(void); + +/* + * skas/process.c + */ +void wait_stub_done(int pid); + +#endif /* __UM_OS_LINUX_INTERNAL_H */ diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c index c8a42ecbd7..f98ff79cdb 100644 --- a/arch/um/os-Linux/main.c +++ b/arch/um/os-Linux/main.c @@ -16,6 +16,7 @@ #include <kern_util.h> #include <os.h> #include <um_malloc.h> +#include "internal.h" #define PGD_BOUND (4 * 1024 * 1024) #define STACKSIZE (8 * 1024 * 1024) @@ -102,8 +103,6 @@ static void setup_env_path(void) } } -extern void scan_elf_aux( char **envp); - int __init main(int argc, char **argv, char **envp) { char **new_argv; @@ -184,6 +183,11 @@ int __init main(int argc, char **argv, char **envp) extern void *__real_malloc(int); +/* workaround for -Wmissing-prototypes warnings */ +void *__wrap_malloc(int size); +void *__wrap_calloc(int n, int size); +void __wrap_free(void *ptr); + void *__wrap_malloc(int size) { void *ret; diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c index c6c9495b14..cf44d386f2 100644 --- a/arch/um/os-Linux/mem.c +++ b/arch/um/os-Linux/mem.c @@ -17,6 +17,7 @@ #include <init.h> #include <kern_util.h> #include <os.h> +#include "internal.h" /* * kasan_map_memory - maps memory from @start with a size of @len. diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c index 24a403a70a..b11ed66c8b 100644 --- a/arch/um/os-Linux/signal.c +++ b/arch/um/os-Linux/signal.c @@ -8,6 +8,7 @@ #include <stdlib.h> #include <stdarg.h> +#include <stdbool.h> #include <errno.h> #include <signal.h> #include <string.h> @@ -65,25 +66,36 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc) int signals_enabled; #ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT -static int signals_blocked; -#else -#define signals_blocked 0 +static int signals_blocked, signals_blocked_pending; #endif static unsigned int signals_pending; static unsigned int signals_active = 0; -void sig_handler(int sig, struct siginfo *si, mcontext_t *mc) +static void sig_handler(int sig, struct siginfo *si, mcontext_t *mc) { int enabled = signals_enabled; - if ((signals_blocked || !enabled) && (sig == SIGIO)) { +#ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT + if ((signals_blocked || + __atomic_load_n(&signals_blocked_pending, __ATOMIC_SEQ_CST)) && + (sig == SIGIO)) { + /* increment so unblock will do another round */ + __atomic_add_fetch(&signals_blocked_pending, 1, + __ATOMIC_SEQ_CST); + return; + } +#endif + + if (!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.) + * handlers. This will mark signals_pending by itself + * (only if necessary.) + * Note we won't get here if signals are hard-blocked + * (which is handled above), in that case the hard- + * unblock will handle things. */ - if (!signals_blocked && time_travel_mode == TT_MODE_EXTERNAL) + if (time_travel_mode == TT_MODE_EXTERNAL) sigio_run_timetravel_handlers(); else signals_pending |= SIGIO_MASK; @@ -108,7 +120,7 @@ static void timer_real_alarm_handler(mcontext_t *mc) timer_handler(SIGALRM, NULL, ®s); } -void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc) +static void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc) { int enabled; @@ -380,33 +392,99 @@ int um_set_signals_trace(int enable) #ifdef UML_CONFIG_UML_TIME_TRAVEL_SUPPORT void mark_sigio_pending(void) { + /* + * It would seem that this should be atomic so + * it isn't a read-modify-write with a signal + * that could happen in the middle, losing the + * value set by the signal. + * + * However, this function is only called when in + * time-travel=ext simulation mode, in which case + * the only signal ever pending is SIGIO, which + * is blocked while this can be called, and the + * timer signal (SIGALRM) cannot happen. + */ signals_pending |= SIGIO_MASK; } void block_signals_hard(void) { - if (signals_blocked) - return; - signals_blocked = 1; + signals_blocked++; barrier(); } void unblock_signals_hard(void) { + static bool unblocking; + if (!signals_blocked) + panic("unblocking signals while not blocked"); + + if (--signals_blocked) return; - /* Must be set to 0 before we check the pending bits etc. */ - signals_blocked = 0; + /* + * Must be set to 0 before we check pending so the + * SIGIO handler will run as normal unless we're still + * going to process signals_blocked_pending. + */ 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(); + /* + * Note that block_signals_hard()/unblock_signals_hard() can be called + * within the unblock_signals()/sigio_run_timetravel_handlers() below. + * This would still be prone to race conditions since it's actually a + * call _within_ e.g. vu_req_read_message(), where we observed this + * issue, which loops. Thus, if the inner call handles the recorded + * pending signals, we can get out of the inner call with the real + * signal hander no longer blocked, and still have a race. Thus don't + * handle unblocking in the inner call, if it happens, but only in + * the outermost call - 'unblocking' serves as an ownership for the + * signals_blocked_pending decrement. + */ + if (unblocking) + return; + unblocking = true; + + while (__atomic_load_n(&signals_blocked_pending, __ATOMIC_SEQ_CST)) { + if (signals_enabled) { + /* signals are enabled so we can touch this */ + signals_pending |= SIGIO_MASK; + /* + * this is a bit inefficient, but that's + * not really important + */ + block_signals(); + unblock_signals(); + } else { + /* + * we need to run time-travel handlers even + * if not enabled + */ + sigio_run_timetravel_handlers(); + } + + /* + * The decrement of signals_blocked_pending must be atomic so + * that the signal handler will either happen before or after + * the decrement, not during a read-modify-write: + * - If it happens before, it can increment it and we'll + * decrement it and do another round in the loop. + * - If it happens after it'll see 0 for both signals_blocked + * and signals_blocked_pending and thus run the handler as + * usual (subject to signals_enabled, but that's unrelated.) + * + * Note that a call to unblock_signals_hard() within the calls + * to unblock_signals() or sigio_run_timetravel_handlers() above + * will do nothing due to the 'unblocking' state, so this cannot + * underflow as the only one decrementing will be the outermost + * one. + */ + if (__atomic_sub_fetch(&signals_blocked_pending, 1, + __ATOMIC_SEQ_CST) < 0) + panic("signals_blocked_pending underflow"); } + + unblocking = false; } #endif diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c index 953fb10f3f..1f9c1bffc3 100644 --- a/arch/um/os-Linux/skas/mem.c +++ b/arch/um/os-Linux/skas/mem.c @@ -17,11 +17,10 @@ #include <skas.h> #include <sysdep/ptrace.h> #include <sysdep/stub.h> +#include "../internal.h" extern char batch_syscall_stub[], __syscall_stub_start[]; -extern void wait_stub_done(int pid); - static inline unsigned long *check_init_stack(struct mm_id * mm_idp, unsigned long *stack) { diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c index 1f5c3f2523..41a288dcfc 100644 --- a/arch/um/os-Linux/skas/process.c +++ b/arch/um/os-Linux/skas/process.c @@ -23,6 +23,7 @@ #include <skas.h> #include <sysdep/stub.h> #include <linux/threads.h> +#include "../internal.h" int is_skas_winch(int pid, int fd, void *data) { diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c index 8b0e98ab84..89ad9f4f86 100644 --- a/arch/um/os-Linux/start_up.c +++ b/arch/um/os-Linux/start_up.c @@ -20,10 +20,12 @@ #include <asm/unistd.h> #include <init.h> #include <os.h> +#include <kern_util.h> #include <mem_user.h> #include <ptrace_user.h> #include <registers.h> #include <skas.h> +#include "internal.h" static void ptrace_child(void) { @@ -221,8 +223,6 @@ static void __init check_ptrace(void) check_sysemu(); } -extern void check_tmpexec(void); - static void __init check_coredump_limit(void) { struct rlimit lim; |