kernel: implement eventfs/eventfd

kernel-src/arch/x86-64/syscall.asm

@@ -105,6 +105,7 @@ extern syscall_getsockopt
 extern syscall_clock_getres
 extern syscall_setpriority
 extern syscall_sysctl
+extern syscall_eventfd
 syscalltab:
 dq syscall_print
 dq syscall_mmap
@@ -212,7 +213,8 @@ dq syscall_getsockopt
 dq syscall_clock_getres
 dq syscall_setpriority
 dq syscall_sysctl
-syscallcount equ 106
+dq syscall_eventfd
+syscallcount equ 107
 section .text
 global arch_syscall_entry
 ; on entry:

kernel-src/arch/x86-64/syscalllog.c

@@ -9,7 +9,7 @@
 void arch_interrupt_disable();
 void arch_interrupt_enable();
 
-#define SYSCALL_COUNT 106
+#define SYSCALL_COUNT 107
 #define LOGSTR(x) arch_e9_puts(x)
 
 static char *name[] = {
@@ -119,6 +119,7 @@ static char *name[] = {
 	"clock_getres",
 	"setpriority",
 	"sysctl",
+	"eventfd",
 };
 
 static char *args[] = {
@@ -228,6 +229,7 @@ static char *args[] = {
 	"clockid %d timespec %p", // clock_getres
 	"which %d who %d prio %d", // setpriority
 	"name %p name_len %lu oldp %p old_size %p newp %p new_size %lu", // sysctl
+	"initval %lu flags %x", //eventfd
 };
 
 #endif

kernel-src/fs/eventfs.c

@@ -0,0 +1,219 @@
+#include <kernel/vfs.h>
+#include <kernel/slab.h>
+#include <logging.h>
+#include <errno.h>
+#include <kernel/poll.h>
+#include <kernel/init.h>
+#include <kernel/eventfs.h>
+
+#define EVENT_COUNTER_MAX 0xfffffffffffffffelu
+
+typedef struct {
+	vnode_t vnode;
+	pollheader_t pollheader;
+	uint64_t counter;
+	bool semaphore;
+} event_node_t;
+
+static scache_t *node_cache;
+
+int eventfs_close(vnode_t *node, int flags, cred_t *cred) {
+	return 0; // not needed
+}
+
+static int internal_poll(event_node_t *event_node, polldata_t *data, int events, size_t write_limit) {
+	int revents = 0;
+
+	if ((events & POLLIN) && event_node->counter)
+		revents |= POLLIN;
+
+	if ((events & POLLOUT) && event_node->counter <= write_limit)
+		revents |= POLLOUT;
+
+	if (data && !revents)
+		poll_add(&event_node->pollheader, data, events);
+
+	return revents;
+}
+
+static int internal_poll_wait(event_node_t *event_node, int event, bool non_blocking, size_t write_limit) {
+	for (;;) {
+		polldesc_t desc = {0};
+		int error = poll_initdesc(&desc, 1);
+		if (error)
+			return error;
+
+		int revents = internal_poll(event_node, &desc.data[0], event, write_limit);
+		if (revents) {
+			poll_leave(&desc);
+			poll_destroydesc(&desc);
+			break;
+		}
+
+		if (non_blocking) {
+			poll_leave(&desc);
+			poll_destroydesc(&desc);
+			return EAGAIN;
+		}
+
+		MUTEX_RELEASE(&event_node->vnode.lock);
+
+		error = poll_dowait(&desc, 0);
+
+		poll_leave(&desc);
+		poll_destroydesc(&desc);
+
+		MUTEX_ACQUIRE(&event_node->vnode.lock);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+int eventfs_read(vnode_t *node, iovec_iterator_t *iovec_iterator, size_t size, uintmax_t offset, int flags, size_t *bytes_read, cred_t *cred) {
+	event_node_t *event_node = (event_node_t *)node;
+
+	if (size < 8)
+		return EINVAL;
+
+	MUTEX_ACQUIRE(&node->lock);
+
+	int error = internal_poll_wait(event_node, POLLIN, flags & V_FFLAGS_NONBLOCKING, 0);
+	if (error)
+		goto leave;
+
+	uint64_t return_value = event_node->semaphore ? 1 : event_node->counter;	
+	error = iovec_iterator_copy_from_buffer(iovec_iterator, &return_value, 8);
+	if (error)
+		goto leave;
+
+	event_node->counter = event_node->semaphore ? (event_node->counter - 1) : 0;
+	*bytes_read = 8;
+
+	poll_event(&event_node->pollheader, POLLOUT);
+
+	leave:
+	MUTEX_RELEASE(&node->lock);
+	return error;
+}
+
+int eventfs_write(vnode_t *node, iovec_iterator_t *iovec_iterator, size_t size, uintmax_t offset, int flags, size_t *bytes_written, cred_t *cred) {
+	event_node_t *event_node = (event_node_t *)node;
+
+	if (size < 8)
+		return EINVAL;
+
+	uint64_t value_to_write;
+	int error = iovec_iterator_copy_to_buffer(iovec_iterator, &value_to_write, 8);
+	if (error)
+		return error;
+
+	if (value_to_write > EVENT_COUNTER_MAX)
+		return EINVAL;
+
+	MUTEX_ACQUIRE(&node->lock);
+
+	error = internal_poll_wait(event_node, POLLOUT, flags & V_FFLAGS_NONBLOCKING, EVENT_COUNTER_MAX - value_to_write);
+	if (error)
+		goto leave;
+
+	event_node->counter += value_to_write;
+	__assert(event_node->counter <= EVENT_COUNTER_MAX);
+
+	poll_event(&event_node->pollheader, POLLIN);
+	*bytes_written = 8;
+
+	leave:
+	MUTEX_RELEASE(&node->lock);
+	return error;
+}
+
+int eventfs_poll(vnode_t *node, polldata_t *data, int events) {
+	MUTEX_ACQUIRE(&node->lock);
+	int revents = internal_poll((event_node_t *)node, data, events, EVENT_COUNTER_MAX - 1);
+	MUTEX_RELEASE(&node->lock);
+	return revents;
+}
+
+static vops_t vnops;
+
+int eventfs_inactive(vnode_t *node) {
+	event_node_t *event_node = (event_node_t *)node;
+	VOP_INIT(&event_node->vnode, &vnops, 0, V_TYPE_CHDEV, NULL);
+	POLL_INITHEADER(&event_node->pollheader);
+	slab_free(node_cache, node);
+	return 0;
+}
+
+static int eventfs_lock(vnode_t *) {
+	return 0;
+}
+
+static int eventfs_unlock(vnode_t *) {
+	return 0;
+}
+
+static int eventfs_advlock(vnode_t *node, int op, advlock_t *advlock) {
+	return vfs_advlock(node, op, advlock);
+}
+
+static int eventfs_enodev() {
+	return ENODEV;
+}
+
+static vops_t vnops = {
+	.create = eventfs_enodev,
+	.open = eventfs_enodev,
+	.close = eventfs_close,
+	.getattr = eventfs_enodev,
+	.setattr = eventfs_enodev,
+	.lookup = eventfs_enodev,
+	.poll = eventfs_poll,
+	.read = eventfs_read,
+	.write = eventfs_write,
+	.access = eventfs_enodev,
+	.unlink = eventfs_enodev,
+	.link = eventfs_enodev,
+	.symlink = eventfs_enodev,
+	.readlink = eventfs_enodev,
+	.inactive = eventfs_inactive,
+	.mmap = eventfs_enodev,
+	.munmap = eventfs_enodev,
+	.getdents = eventfs_enodev,
+	.resize = eventfs_enodev,
+	.rename = eventfs_enodev,
+	.ioctl = eventfs_enodev,
+	.putpage = eventfs_enodev,
+	.getpage = eventfs_enodev,
+	.sync = eventfs_enodev,
+	.advlock = eventfs_advlock,
+	.lock = eventfs_lock,
+	.unlock = eventfs_unlock
+};
+
+static bool ctor(scache_t *cache, void *obj) {
+	event_node_t *node = obj;
+	VOP_INIT(&node->vnode, &vnops, 0, V_TYPE_CHDEV, NULL);
+	POLL_INITHEADER(&node->pollheader);
+	return true;
+}
+
+void eventfs_init() {
+	node_cache = slab_newcache(sizeof(event_node_t), 0, ctor, NULL);
+	__assert(node_cache);
+}
+
+INIT_ROUTINE_DEFINE(eventfs, INIT_ROUTINE_FLAGS_NONE, eventfs_init, bsp_early);
+
+int eventfs_create_node(vnode_t **vnodep, size_t initval, bool semaphore) {
+	event_node_t *event_node = slab_allocate(node_cache);
+	if (event_node == NULL)
+		return ENOMEM;
+
+	event_node->counter = initval;
+	event_node->semaphore = semaphore;
+
+	*vnodep = &event_node->vnode;
+	return 0;
+}

kernel-src/include/kernel/eventfs.h

@@ -0,0 +1,8 @@
+#ifndef _EVENTFS_H
+#define _EVENTFS_H
+
+#include <kernel/vfs.h>
+
+int eventfs_create_node(vnode_t **vnodep, size_t initval, bool semaphore);
+
+#endif

kernel-src/sys/syscalls/eventfd.c

@@ -0,0 +1,40 @@
+#include <kernel/syscalls.h>
+#include <kernel/eventfs.h>
+
+#define EFD_CLOEXEC O_CLOEXEC
+#define EFD_NONBLOCK O_NONBLOCK
+#define EFD_SEMAPHORE 1
+
+#define KNOWN_FLAGS (EFD_CLOEXEC | EFD_NONBLOCK | EFD_SEMAPHORE)
+
+syscallret_t syscall_eventfd(context_t *, size_t initval, int flags) {
+	syscallret_t ret = {
+		.ret = -1
+	};
+
+	if (flags & ~KNOWN_FLAGS) {
+		ret.errno = EINVAL;
+		return ret;
+	}
+
+	vnode_t *vnode;
+	ret.errno = eventfs_create_node(&vnode, initval, flags & EFD_SEMAPHORE);
+	if (ret.errno)
+		return ret;
+
+	file_t *file;
+	int fd;
+	ret.errno = fd_new((flags & EFD_CLOEXEC) ? O_CLOEXEC : 0, &file, &fd);
+	if (ret.errno) {
+		VOP_RELEASE(vnode);
+		return ret;
+	}
+
+	file->vnode = vnode;
+	file->flags = FILE_WRITE | FILE_READ | ((flags & EFD_NONBLOCK) ? O_NONBLOCK : 0);
+	file->offset = 0;
+	file->mode = 0666;
+
+	ret.ret = fd;
+	return ret;
+}

patches/mlibc/jinx-working-patch.patch

@@ -452,7 +452,7 @@ index a86353f..3e1a18c 100644
  	return error ? -1 : ret;
  }
 diff --git mlibc-clean/sysdeps/astral/generic/generic.cpp mlibc-workdir/sysdeps/astral/generic/generic.cpp
-index 3b04372..b7a8ab7 100644
+index 3b04372..5324a35 100644
 --- mlibc-clean/sysdeps/astral/generic/generic.cpp
 +++ mlibc-workdir/sysdeps/astral/generic/generic.cpp
 @@ -1,7 +1,9 @@
@@ -497,7 +497,7 @@ index 3b04372..b7a8ab7 100644
  
  namespace mlibc {
  	int Sysdeps<SetGroups>::operator()(size_t size, const gid_t *list) {
-@@ -31,14 +56,313 @@ namespace mlibc {
+@@ -31,15 +56,324 @@ namespace mlibc {
  		return 0;
  	}
  
@@ -627,9 +627,9 @@ index 3b04372..b7a8ab7 100644
 +	int Sysdeps<GetCurrentStackInfo>::operator()(void **stack_base, size_t *stack_size) {
 +		*stack_size = 1024 * 1024 * 4;
 +		*stack_base = (void *)(0x0000800000000000 - *stack_size);
-+		return 0;
-+	}
-+
+ 		return 0;
+ 	}
+ 
 +#ifndef MLIBC_BUILDING_RTLD
 +	int Sysdeps<Getifaddrs>::operator()(struct ifaddrs **out) {
 +		struct ifaddrs *list = nullptr;
@@ -804,19 +804,30 @@ index 3b04372..b7a8ab7 100644
 +		*out = arr;
 +		freeifaddrs(ifaddrs);
 +
- 		return 0;
- 	}
++		return 0;
++	}
 +#endif
 +
++	int Sysdeps<EventfdCreate>::operator()(unsigned int initval, int flags, int *fd) {
++		long ret;
++		int error = syscall(SYSCALL_EVENTFD, &ret, initval, flags);
++		if (error)
++			return error;
++
++		*fd = ret;
++		return 0;
++	}
++
 +	int Sysdeps<GetSockopt>::operator()(int fd, int layer, int number,
 +		void *__restrict buffer, socklen_t *__restrict size) {
 +		long ret;
 +		return syscall(SYSCALL_GETSOCKOPT, &ret, fd, layer, number, (uint64_t)buffer, (uint64_t)size);
 +	}
- 
++
  	int Sysdeps<InetConfigured>::operator()(bool *ipv4, bool *ipv6) {
  		// there is no ipv6 support in the kernel currently and no way of checking for configured interfaces
-@@ -47,6 +371,71 @@ namespace mlibc {
+ 		*ipv4 = true;
+@@ -47,6 +381,71 @@ namespace mlibc {
  		return 0;
  	}
  
@@ -888,7 +899,7 @@ index 3b04372..b7a8ab7 100644
  	int Sysdeps<Readv>::operator()(int fd, const struct iovec *iovs, int iovc, ssize_t *bytes_read) {
  		long r;
  		int error = syscall(SYSCALL_READV, &r, fd, (uint64_t)iovs, iovc);
-@@ -86,6 +475,11 @@ namespace mlibc {
+@@ -86,6 +485,11 @@ namespace mlibc {
  		return e;
  	}
  
@@ -900,7 +911,7 @@ index 3b04372..b7a8ab7 100644
  	int Sysdeps<Shutdown>::operator()(int sockfd, int how) {
  		long ret;
  		return syscall(SYSCALL_SHUTDOWN, &ret, sockfd, how);
-@@ -487,8 +881,15 @@ namespace mlibc {
+@@ -487,8 +891,15 @@ namespace mlibc {
  		return err;
  	}
  
@@ -916,7 +927,7 @@ index 3b04372..b7a8ab7 100644
  		return syscall(SYSCALL_SETSOCKOPT, &ret, fd, layer, number, (uint64_t)buffer, size);
  	}
  
-@@ -511,6 +912,11 @@ namespace mlibc {
+@@ -511,6 +922,11 @@ namespace mlibc {
  		return err;
  	}
  
@@ -928,7 +939,7 @@ index 3b04372..b7a8ab7 100644
  	int Sysdeps<Renameat>::operator()(int olddirfd, const char *old_path, int newdirfd, const char *new_path) {
  		long ret;
  		return syscall(SYSCALL_RENAMEAT, &ret, olddirfd, (uint64_t)old_path, newdirfd, (uint64_t)new_path);
-@@ -562,6 +968,16 @@ namespace mlibc {
+@@ -562,6 +978,16 @@ namespace mlibc {
  		return sysdep<Ioctl>(fd, TCSETS, (void *)attr, &res);
  	}
  
@@ -945,7 +956,7 @@ index 3b04372..b7a8ab7 100644
  	int Sysdeps<Poll>::operator()(struct pollfd *fds, nfds_t count, int timeout, int *num_events) {
  		long ret;
  		long error = syscall(SYSCALL_POLL, &ret, (uint64_t)fds, count, timeout);
-@@ -932,4 +1348,13 @@ namespace mlibc {
+@@ -932,4 +1358,13 @@ namespace mlibc {
  		*nanos = ts.tv_nsec;
  		return err;
  	}
@@ -982,10 +993,10 @@ index 7e4f2a1..ecc2677 100644
  #ifdef __cplusplus
  extern "C" {
 diff --git mlibc-clean/sysdeps/astral/include/astral/syscall.h mlibc-workdir/sysdeps/astral/include/astral/syscall.h
-index a6c4067..160a140 100644
+index a6c4067..9040d45 100644
 --- mlibc-clean/sysdeps/astral/include/astral/syscall.h
 +++ mlibc-workdir/sysdeps/astral/include/astral/syscall.h
-@@ -103,6 +103,13 @@
+@@ -103,6 +103,14 @@
  #define SYSCALL_SYSINFO 96
  #define SYSCALL_WRITEV 97
  #define SYSCALL_READV 98
@@ -996,6 +1007,7 @@ index a6c4067..160a140 100644
 +#define SYSCALL_CLOCK_GETRES 103
 +#define SYSCALL_SETPRIORITY 104
 +#define SYSCALL_SYSCTL 105
++#define SYSCALL_EVENTFD 106
  
  #ifndef __MLIBC_ABI_ONLY
  
@@ -1062,7 +1074,7 @@ index 0000000..161f634
 +
 +#endif /* _ASTRAL_SYSCTL_H */
 diff --git mlibc-clean/sysdeps/astral/include/mlibc/sysdeps.hpp mlibc-workdir/sysdeps/astral/include/mlibc/sysdeps.hpp
-index ce91084..54ee08e 100644
+index ce91084..503110a 100644
 --- mlibc-clean/sysdeps/astral/include/mlibc/sysdeps.hpp
 +++ mlibc-workdir/sysdeps/astral/include/mlibc/sysdeps.hpp
 @@ -7,8 +7,30 @@ namespace mlibc {
@@ -1121,7 +1133,7 @@ index ce91084..54ee08e 100644
  	Poll,
  	Ppoll,
  	Pselect,
-@@ -135,7 +161,10 @@ struct AstralSysdepTags :
+@@ -135,7 +161,11 @@ struct AstralSysdepTags :
  	VmUnmap,
  	Isatty,
  	ClockGet,
@@ -1129,7 +1141,8 @@ index ce91084..54ee08e 100644
 +	ClockGetres,
 +	PrepareStack,
 +	SetPriority,
-+	GetCurrentStackInfo
++	GetCurrentStackInfo,
++	EventfdCreate
  {};
  
  template<typename Tag>