static int do_kexec_load(unsigned long entry, unsigned long nr_segments, struct kexec_segment __user *segments, unsigned long flags) { struct kimage **dest_image, *image; unsigned long i; int ret; if (flags & KEXEC_ON_CRASH) { dest_image = &kexec_crash_image; if (kexec_crash_image) arch_kexec_unprotect_crashkres(); } else { dest_image = &kexec_image; } if (nr_segments == 0) { /* Uninstall image */ kimage_free(xchg(dest_image, NULL)); return 0; } if (flags & KEXEC_ON_CRASH) { /* * Loading another kernel to switch to if this one * crashes. Free any current crash dump kernel before * we corrupt it. */ kimage_free(xchg(&kexec_crash_image, NULL)); } ret = kimage_alloc_init(&image, entry, nr_segments, segments, flags); if (ret) return ret; if (flags & KEXEC_PRESERVE_CONTEXT) image->preserve_context = 1; ret = machine_kexec_prepare(image); if (ret) goto out; /* * Some architecture(like S390) may touch the crash memory before * machine_kexec_prepare(), we must copy vmcoreinfo data after it. */ ret = kimage_crash_copy_vmcoreinfo(image); if (ret) goto out; for (i = 0; i < nr_segments; i++) { ret = kimage_load_segment(image, &image->segment[i]); if (ret) goto out; } kimage_terminate(image); /* Install the new kernel and uninstall the old */ image = xchg(dest_image, image); out: if ((flags & KEXEC_ON_CRASH) && kexec_crash_image) arch_kexec_protect_crashkres(); kimage_free(image); return ret; }
SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, struct kexec_segment __user *, segments, unsigned long, flags) { struct kimage **dest_image, *image; int result; /* We only trust the superuser with rebooting the system. */ if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) return -EPERM; /* * Verify we have a legal set of flags * This leaves us room for future extensions. */ if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK)) return -EINVAL; /* Verify we are on the appropriate architecture */ if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) && ((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT)) return -EINVAL; /* Put an artificial cap on the number * of segments passed to kexec_load. */ if (nr_segments > KEXEC_SEGMENT_MAX) return -EINVAL; image = NULL; result = 0; /* Because we write directly to the reserved memory * region when loading crash kernels we need a mutex here to * prevent multiple crash kernels from attempting to load * simultaneously, and to prevent a crash kernel from loading * over the top of a in use crash kernel. * * KISS: always take the mutex. */ if (!mutex_trylock(&kexec_mutex)) return -EBUSY; dest_image = &kexec_image; if (flags & KEXEC_ON_CRASH) dest_image = &kexec_crash_image; if (nr_segments > 0) { unsigned long i; if (flags & KEXEC_ON_CRASH) { /* * Loading another kernel to switch to if this one * crashes. Free any current crash dump kernel before * we corrupt it. */ kimage_free(xchg(&kexec_crash_image, NULL)); result = kimage_alloc_init(&image, entry, nr_segments, segments, flags); crash_map_reserved_pages(); } else { /* Loading another kernel to reboot into. */ result = kimage_alloc_init(&image, entry, nr_segments, segments, flags); } if (result) goto out; if (flags & KEXEC_PRESERVE_CONTEXT) image->preserve_context = 1; result = machine_kexec_prepare(image); if (result) goto out; for (i = 0; i < nr_segments; i++) { result = kimage_load_segment(image, &image->segment[i]); if (result) goto out; } kimage_terminate(image); if (flags & KEXEC_ON_CRASH) crash_unmap_reserved_pages(); } /* Install the new kernel, and Uninstall the old */ image = xchg(dest_image, image); out: mutex_unlock(&kexec_mutex); kimage_free(image); return result; }