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Subject[PATCH nolibc 57/61] tools/nolibc/sys: Implement `mmap()` and `munmap()`
Date
From: Ammar Faizi <ammarfaizi2@gnuweeb.org>

Implement mmap() and munmap(). Currently, they are only available for
architecures that have my_syscall6 macro. For architectures that don't
have, this function will return -1 with errno set to ENOSYS (Function
not implemented).

This has been tested on x86 and i386.

Notes for i386:
1) The common mmap() syscall implementation uses __NR_mmap2 instead
of __NR_mmap.

2) The offset must be shifted-right by 12-bit.

Acked-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
---
tools/include/nolibc/sys.h | 62 ++++++++++++++++++++++++++++++++++++++
1 file changed, 62 insertions(+)

diff --git a/tools/include/nolibc/sys.h b/tools/include/nolibc/sys.h
index 4d4308d5d111..08491070387b 100644
--- a/tools/include/nolibc/sys.h
+++ b/tools/include/nolibc/sys.h
@@ -14,6 +14,7 @@
#include <asm/unistd.h>
#include <asm/signal.h> // for SIGCHLD
#include <asm/ioctls.h>
+#include <asm/mman.h>
#include <linux/fs.h>
#include <linux/loop.h>
#include <linux/time.h>
@@ -675,6 +676,67 @@ int mknod(const char *path, mode_t mode, dev_t dev)
return ret;
}

+#ifndef MAP_SHARED
+#define MAP_SHARED 0x01 /* Share changes */
+#define MAP_PRIVATE 0x02 /* Changes are private */
+#define MAP_SHARED_VALIDATE 0x03 /* share + validate extension flags */
+#endif
+
+#ifndef MAP_FAILED
+#define MAP_FAILED ((void *)-1)
+#endif
+
+static __attribute__((unused))
+void *sys_mmap(void *addr, size_t length, int prot, int flags, int fd,
+ off_t offset)
+{
+#ifndef my_syscall6
+ /* Function not implemented. */
+ return -ENOSYS;
+#else
+
+ int n;
+
+#if defined(__i386__)
+ n = __NR_mmap2;
+ offset >>= 12;
+#else
+ n = __NR_mmap;
+#endif
+
+ return (void *)my_syscall6(n, addr, length, prot, flags, fd, offset);
+#endif
+}
+
+static __attribute__((unused))
+void *mmap(void *addr, size_t length, int prot, int flags, int fd, off_t offset)
+{
+ void *ret = sys_mmap(addr, length, prot, flags, fd, offset);
+
+ if ((unsigned long)ret >= -4095UL) {
+ SET_ERRNO(-(long)ret);
+ ret = MAP_FAILED;
+ }
+ return ret;
+}
+
+static __attribute__((unused))
+int sys_munmap(void *addr, size_t length)
+{
+ return my_syscall2(__NR_munmap, addr, length);
+}
+
+static __attribute__((unused))
+int munmap(void *addr, size_t length)
+{
+ int ret = sys_munmap(addr, length);
+
+ if (ret < 0) {
+ SET_ERRNO(-ret);
+ ret = -1;
+ }
+ return ret;
+}

/*
* int mount(const char *source, const char *target,
--
2.31.1.189.g2e36527f23
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