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kexec: support for kexec on panic using new system call

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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>
This commit is contained in:
Vivek Goyal 2014-08-08 14:26:09 -07:00 • committed by Linus Torvalds
parent 27f48d3e63
commit dd5f726076
7 changed files with 725 additions and 26 deletions
Download patch file Download diff file Expand all files Collapse all files

46
kernel/kexec.c
View file

@ -548,6 +548,7 @@ kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
{
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 @@ kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
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 @@ kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
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 @@ static int kimage_load_crash_segment(struct kimage *image,
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 @@ static int kimage_load_crash_segment(struct kimage *image,
/* 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 @@ static int kimage_load_crash_segment(struct kimage *image,
}
ubytes -= uchunk;
maddr += mchunk;
buf += mchunk;
if (image->file_mode)
kbuf += mchunk;
else
buf += mchunk;
mbytes -= mchunk;
}
out:
@ -2127,7 +2148,14 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
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;