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kernel/kexec_file.c: allow archs to set purgatory load address

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For s390 new kernels are loaded to fixed addresses in memory before they
are booted.  With the current code this is a problem as it assumes the
kernel will be loaded to an 'arbitrary' address.  In particular,
kexec_locate_mem_hole searches for a large enough memory region and sets
the load address (kexec_bufer->mem) to it.

Luckily there is a simple workaround for this problem.  By returning 1
in arch_kexec_walk_mem, kexec_locate_mem_hole is turned off.  This
allows the architecture to set kbuf->mem by hand.  While the trick works
fine for the kernel it does not for the purgatory as here the
architectures don't have access to its kexec_buffer.

Give architectures access to the purgatories kexec_buffer by changing
kexec_load_purgatory to take a pointer to it.  With this change
architectures have access to the buffer and can edit it as they need.

A nice side effect of this change is that we can get rid of the
purgatory_info->purgatory_load_address field.  As now the information
stored there can directly be accessed from kbuf->mem.

Link: http://lkml.kernel.org/r/20180321112751.22196-11-prudo@linux.vnet.ibm.com
Signed-off-by: Philipp Rudo <prudo@linux.vnet.ibm.com>
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Philipp Rudo 2018-04-13 15:36:43 -07:00 • committed by Linus Torvalds
parent 8da0b72495
commit 3be3f61d25
4 changed files with 31 additions and 32 deletions
Download patch file Download diff file Expand all files Collapse all files

29
kernel/kexec_file.c
View file

@ -730,8 +730,8 @@ static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
int i, ret;
sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
bss_align = 1;
bss_sz = 0;
kbuf->buf_align = bss_align = 1;
kbuf->bufsz = bss_sz = 0;
for (i = 0; i < pi->ehdr->e_shnum; i++) {
if (!(sechdrs[i].sh_flags & SHF_ALLOC))
@ -763,7 +763,6 @@ static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
ret = kexec_add_buffer(kbuf);
if (ret)
goto out;
pi->purgatory_load_addr = kbuf->mem;
return 0;
out:
@ -901,27 +900,32 @@ static int kexec_apply_relocations(struct kimage *image)
return 0;
}
/* Load relocatable purgatory object and relocate it appropriately */
int kexec_load_purgatory(struct kimage *image, unsigned long min,
unsigned long max, int top_down,
unsigned long *load_addr)
/*
* kexec_load_purgatory - Load and relocate the purgatory object.
* @image: Image to add the purgatory to.
* @kbuf: Memory parameters to use.
*
* Allocates the memory needed for image->purgatory_info.sechdrs and
* image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
* to free the memory after use.
*
* Return: 0 on success, negative errno on error.
*/
int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
{
struct purgatory_info *pi = &image->purgatory_info;
int ret;
struct kexec_buf kbuf = { .image = image, .bufsz = 0, .buf_align = 1,
.buf_min = min, .buf_max = max,
.top_down = top_down };
if (kexec_purgatory_size <= 0)
return -EINVAL;
pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
ret = kexec_purgatory_setup_kbuf(pi, &kbuf);
ret = kexec_purgatory_setup_kbuf(pi, kbuf);
if (ret)
return ret;
ret = kexec_purgatory_setup_sechdrs(pi, &kbuf);
ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
if (ret)
goto out_free_kbuf;
@ -929,7 +933,6 @@ int kexec_load_purgatory(struct kimage *image, unsigned long min,
if (ret)
goto out;
*load_addr = pi->purgatory_load_addr;
return 0;
out:
vfree(pi->sechdrs);