!337 移动预留主线程信号栈代码到libc

Merge pull request !337 from klcf0220/master

musl_src.gni

@@ -1876,6 +1876,7 @@ musl_src_porting_file = [
   "src/info/device_api_version.c",
   "src/info/fatal_message.c",
   "src/env/__init_tls.c",
+  "src/env/__libc_start_main.c",
   "src/internal/pthread_impl.h",
   "src/internal/syscall.h",
   "ldso/namespace.h",

porting/linux/user/src/env/__libc_start_main.c

+#include <elf.h>
+#include <poll.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <unistd.h>
+#include "syscall.h"
+#include "atomic.h"
+#include "libc.h"
+#include "pthread_impl.h"
+
+static void dummy(void) {}
+weak_alias(dummy, _init);
+
+extern weak hidden void (*const __init_array_start)(void), (*const __init_array_end)(void);
+
+static void dummy1(void *p) {}
+weak_alias(dummy1, __init_ssp);
+
+#define AUX_CNT 38
+
+#ifdef __GNUC__
+__attribute__((__noinline__))
+#endif
+void __init_libc(char **envp, char *pn)
+{
+	size_t i, *auxv, aux[AUX_CNT] = { 0 };
+	__environ = envp;
+	for (i=0; envp[i]; i++);
+	libc.auxv = auxv = (void *)(envp+i+1);
+	for (i=0; auxv[i]; i+=2) if (auxv[i]<AUX_CNT) aux[auxv[i]] = auxv[i+1];
+	__hwcap = aux[AT_HWCAP];
+	if (aux[AT_SYSINFO]) __sysinfo = aux[AT_SYSINFO];
+	libc.page_size = aux[AT_PAGESZ];
+
+	if (!pn) pn = (void*)aux[AT_EXECFN];
+	if (!pn) pn = "";
+	__progname = __progname_full = pn;
+	for (i=0; pn[i]; i++) if (pn[i]=='/') __progname = pn+i+1;
+
+	__init_tls(aux);
+	__init_ssp((void *)aux[AT_RANDOM]);
+
+	if (aux[AT_UID]==aux[AT_EUID] && aux[AT_GID]==aux[AT_EGID]
+		&& !aux[AT_SECURE]) return;
+
+	struct pollfd pfd[3] = { {.fd=0}, {.fd=1}, {.fd=2} };
+	int r =
+#ifdef SYS_poll
+	__syscall(SYS_poll, pfd, 3, 0);
+#else
+	__syscall(SYS_ppoll, pfd, 3, &(struct timespec){0}, 0, _NSIG/8);
+#endif
+	if (r<0) a_crash();
+	for (i=0; i<3; i++) if (pfd[i].revents&POLLNVAL)
+		if (__sys_open("/dev/null", O_RDWR)<0)
+			a_crash();
+	libc.secure = 1;
+}
+
+static void libc_start_init(void)
+{
+	_init();
+	uintptr_t a = (uintptr_t)&__init_array_start;
+	for (; a<(uintptr_t)&__init_array_end; a+=sizeof(void(*)()))
+		(*(void (**)(void))a)();
+}
+
+weak_alias(libc_start_init, __libc_start_init);
+
+typedef int lsm2_fn(int (*)(int,char **,char **), int, char **);
+static lsm2_fn libc_start_main_stage2;
+
+int __libc_start_main(int (*main)(int,char **,char **), int argc, char **argv)
+{
+	char **envp = argv+argc+1;
+
+	/* External linkage, and explicit noinline attribute if available,
+	 * are used to prevent the stack frame used during init from
+	 * persisting for the entire process lifetime. */
+	__init_libc(envp, argv[0]);
+
+	/* Barrier against hoisting application code or anything using ssp
+	 * or thread pointer prior to its initialization above. */
+	lsm2_fn *stage2 = libc_start_main_stage2;
+	__asm__ ( "" : "+r"(stage2) : : "memory" );
+	return stage2(main, argc, argv);
+}
+
+static int libc_start_main_stage2(int (*main)(int,char **,char **), int argc, char **argv)
+{
+	char **envp = argv+argc+1;
+	__libc_start_init();
+#ifdef RESERVE_SIGNAL_STACK
+	pthread_reserve_signal_stack();
+#endif
+
+	/* Pass control to the application */
+	exit(main(argc, argv, envp));
+	return 0;
+}

porting/linux/user/src/internal/pthread_impl.h

@@ -223,6 +223,11 @@ static inline void __absolute_timespec_from_timespec(struct timespec *abs_ts,
     }
 }
 
+#ifdef RESERVE_SIGNAL_STACK
+hidden void pthread_reserve_signal_stack();
+hidden void pthread_release_signal_stack();
+#endif
+
 hidden void __acquire_ptc(void);
 hidden void __release_ptc(void);
 hidden void __inhibit_ptc(void);

porting/linux/user/src/thread/pthread_create.c

@@ -42,7 +42,7 @@ void stack_naming(struct pthread *new){
 #else
 #define RESERVE_SIGNAL_STACK_SIZE (20 * 1024)
 #endif
-static void __pthread_reserve_signal_stack()
+void __pthread_reserve_signal_stack()
 {
 	void* stack = mmap(NULL, RESERVE_SIGNAL_STACK_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1 , 0);
 	if (stack != MAP_FAILED) {
@@ -60,11 +60,13 @@ static void __pthread_reserve_signal_stack()
 
 	pthread_t self = __pthread_self();
 	self->signal_stack = stack;
-	prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, signal_stack.ss_sp, signal_stack.ss_size, "signal_stack:musl");
+	char name[ANON_STACK_NAME_SIZE];
+	snprintf(name, ANON_STACK_NAME_SIZE, "signal_stack:%d", __pthread_self()->tid);
+	prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, signal_stack.ss_sp, signal_stack.ss_size, name);
 	return;
 }
 
-static void __pthread_release_signal_stack()
+void __pthread_release_signal_stack()
 {
 	pthread_t self = __pthread_self();
 	if (self->signal_stack == NULL) {
@@ -78,6 +80,9 @@ static void __pthread_release_signal_stack()
 	munmap(self->signal_stack, RESERVE_SIGNAL_STACK_SIZE);
 	self->signal_stack = NULL;
 }
+
+weak_alias(__pthread_reserve_signal_stack, pthread_reserve_signal_stack);
+weak_alias(__pthread_release_signal_stack, pthread_release_signal_stack);
 #endif
 
 static void dummy_0()