#ifndef _STAPDYN_COPY_C_
#define _STAPDYN_COPY_C_
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <sys/uio.h>
+
#include "stp_string.c"
static int _stp_mem_fd = -1;
+
+static inline __must_check ssize_t __self_readv(const struct iovec *lvec,
+ unsigned long liovcnt,
+ const struct iovec *rvec,
+ unsigned long riovcnt)
+{
+#if !__GLIBC_PREREQ(2, 15)
+#ifdef __NR_process_vm_readv
+#define process_vm_readv(...) \
+ syscall(__NR_process_vm_readv, __VA_ARGS__)
+#else
+#define process_vm_readv(...) \
+ ({ (void)lvec; (void)liovcnt; \
+ (void)rvec; (void)riovcnt; \
+ errno = ENOSYS; -1 })
+#endif
+#endif
+ return process_vm_readv(getpid(), lvec, liovcnt, rvec, riovcnt, 0UL);
+}
+
+static inline __must_check ssize_t __self_writev(const struct iovec *lvec,
+ unsigned long liovcnt,
+ const struct iovec *rvec,
+ unsigned long riovcnt)
+{
+#if !__GLIBC_PREREQ(2, 15)
+#ifdef __NR_process_vm_writev
+#define process_vm_writev(...) \
+ syscall(__NR_process_vm_writev, __VA_ARGS__)
+#else
+#define process_vm_writev(...) \
+ ({ (void)lvec; (void)liovcnt; \
+ (void)rvec; (void)riovcnt; \
+ errno = ENOSYS; -1 })
+#endif
+#endif
+ return process_vm_writev(getpid(), lvec, liovcnt, rvec, riovcnt, 0UL);
+}
+
+
+static int _stp_copy_init(void)
+{
+ /* Try a no-op process_vm_readv/writev to make sure they're available,
+ * esp. not ENOSYS, then we don't need to bother /proc/self/mem. */
+ if ((__self_readv(NULL, 0, NULL, 0) == 0) &&
+ (__self_writev(NULL, 0, NULL, 0) == 0))
+ return 0;
+
+ _stp_mem_fd = open("/proc/self/mem", O_RDWR /*| O_LARGEFILE*/);
+ if (_stp_mem_fd < 0)
+ return -errno;
+ fcntl(_stp_mem_fd, F_SETFD, FD_CLOEXEC);
+ return 0;
+}
+
+static void _stp_copy_destroy(void)
+{
+ if (_stp_mem_fd >= 0) {
+ close (_stp_mem_fd);
+ _stp_mem_fd = -1;
+ }
+}
+
+
static inline __must_check long __copy_from_user(void *to,
const void __user * from, unsigned long n)
{
int rc = 0;
- /*
- * The pread syscall is faster than lseek()/read() (since it
- * is only one syscall). Also, if we used lseek()/read() we
- * couldn't use a cached fd - since 2 threads might hit this
- * code at the same time and the 2nd lseek() might finish
- * before the 1st read()...
- */
- if (pread(_stp_mem_fd, to, n, (off_t)(uintptr_t)from) != n)
- rc = -EFAULT;
+ if (_stp_mem_fd >= 0) {
+ /* pread is like lseek+read, without racing other threads. */
+ if (pread(_stp_mem_fd, to, n, (off_t)(uintptr_t)from) != n)
+ rc = -EFAULT;
+ } else {
+ struct iovec lvec = { .iov_base = to, .iov_len = n };
+ struct iovec rvec = { .iov_base = (void *)from, .iov_len = n };
+ if (__self_readv(&lvec, 1, &rvec, 1) != n)
+ rc = -EFAULT;
+ }
+
return rc;
}
{
int rc = 0;
- /*
- * The pwrite syscall is faster than lseek()/write() (since it
- * is only one syscall).
- */
- if (pwrite(_stp_mem_fd, from, n, (off_t)(uintptr_t)to) != n)
- rc = -EFAULT;
+ if (_stp_mem_fd >= 0) {
+ /* pwrite is like lseek+write, without racing other threads. */
+ /* NB: some kernels will refuse to write /proc/self/mem */
+ if (pwrite(_stp_mem_fd, from, n, (off_t)(uintptr_t)to) != n)
+ rc = -EFAULT;
+ } else {
+ struct iovec lvec = { .iov_base = (void *)from, .iov_len = n };
+ struct iovec rvec = { .iov_base = to, .iov_len = n };
+ if (__self_writev(&lvec, 1, &rvec, 1) != n)
+ rc = -EFAULT;
+ }
+
return rc;
}