kexec: support for kexec on panic using new system call
This patch adds support for loading a kexec on panic (kdump) kernel usning
new system call.
It prepares ELF headers for memory areas to be dumped and for saved cpu
registers. Also prepares the memory map for second kernel and limits its
boot to reserved areas only.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Greg Kroah-Hartman <greg@kroah.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: WANG Chao <chaowang@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/kexec.c b/kernel/kexec.c
index 0926f2a..f18c780 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -548,6 +548,7 @@
{
int ret;
struct kimage *image;
+ bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
image = do_kimage_alloc_init();
if (!image)
@@ -555,6 +556,12 @@
image->file_mode = 1;
+ if (kexec_on_panic) {
+ /* Enable special crash kernel control page alloc policy. */
+ image->control_page = crashk_res.start;
+ image->type = KEXEC_TYPE_CRASH;
+ }
+
ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
cmdline_ptr, cmdline_len, flags);
if (ret)
@@ -572,10 +579,12 @@
goto out_free_post_load_bufs;
}
- image->swap_page = kimage_alloc_control_pages(image, 0);
- if (!image->swap_page) {
- pr_err(KERN_ERR "Could not allocate swap buffer\n");
- goto out_free_control_pages;
+ if (!kexec_on_panic) {
+ image->swap_page = kimage_alloc_control_pages(image, 0);
+ if (!image->swap_page) {
+ pr_err(KERN_ERR "Could not allocate swap buffer\n");
+ goto out_free_control_pages;
+ }
}
*rimage = image;
@@ -1113,10 +1122,14 @@
unsigned long maddr;
size_t ubytes, mbytes;
int result;
- unsigned char __user *buf;
+ unsigned char __user *buf = NULL;
+ unsigned char *kbuf = NULL;
result = 0;
- buf = segment->buf;
+ if (image->file_mode)
+ kbuf = segment->kbuf;
+ else
+ buf = segment->buf;
ubytes = segment->bufsz;
mbytes = segment->memsz;
maddr = segment->mem;
@@ -1139,7 +1152,12 @@
/* Zero the trailing part of the page */
memset(ptr + uchunk, 0, mchunk - uchunk);
}
- result = copy_from_user(ptr, buf, uchunk);
+
+ /* For file based kexec, source pages are in kernel memory */
+ if (image->file_mode)
+ memcpy(ptr, kbuf, uchunk);
+ else
+ result = copy_from_user(ptr, buf, uchunk);
kexec_flush_icache_page(page);
kunmap(page);
if (result) {
@@ -1148,7 +1166,10 @@
}
ubytes -= uchunk;
maddr += mchunk;
- buf += mchunk;
+ if (image->file_mode)
+ kbuf += mchunk;
+ else
+ buf += mchunk;
mbytes -= mchunk;
}
out:
@@ -2127,7 +2148,14 @@
kbuf->top_down = top_down;
/* Walk the RAM ranges and allocate a suitable range for the buffer */
- ret = walk_system_ram_res(0, -1, kbuf, locate_mem_hole_callback);
+ if (image->type == KEXEC_TYPE_CRASH)
+ ret = walk_iomem_res("Crash kernel",
+ IORESOURCE_MEM | IORESOURCE_BUSY,
+ crashk_res.start, crashk_res.end, kbuf,
+ locate_mem_hole_callback);
+ else
+ ret = walk_system_ram_res(0, -1, kbuf,
+ locate_mem_hole_callback);
if (ret != 1) {
/* A suitable memory range could not be found for buffer */
return -EADDRNOTAVAIL;