Hi AKASHI
On Thu, 22 Feb 2018 20:17:22 +0900
AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx> wrote:
[...]
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 990adae52151..a6d14a768b3e 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -26,34 +26,83 @@
> #include <linux/vmalloc.h>
> #include "kexec_internal.h"
>
> +const __weak struct kexec_file_ops * const kexec_file_loaders[] = {NULL};
> +
Having a weak definition of kexec_file_loaders causes trouble on s390 with
gcc 4.8 (newer versions seem to work fine). For me it looks like that in this
version gcc doesn't recognize __weak but use the default value for
optimization. This leads to _kexec_kernel_image_probe to always return ENOEXEC
because the for-loop gets optimized out.
The problem can easily be worked around by declaring kexec_file_loaders in
include/linux/kexec.h and defining it in arch code. In particular doing this
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 37e9dce518aa..fc0788540d90 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -139,6 +139,8 @@ struct kexec_file_ops {
#endif
};
+extern const struct kexec_file_ops * const kexec_file_loaders[];
+
/**
* struct kexec_buf - parameters for finding a place for a buffer in memory
* @image: kexec image in which memory to search.
diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index 17ba407d0e79..4e3d1e4bc7f6 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -31,8 +31,6 @@
#include <linux/vmalloc.h>
#include "kexec_internal.h"
-const __weak struct kexec_file_ops * const kexec_file_loaders[] = {NULL};
-
#ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
static int kexec_calculate_store_digests(struct kimage *image);
#else
A nice side effect of this solution is, that a developer who forgets to define
kexec_file_loaders gets a linker error. So he directly knows what's missing
instead of first having to find out where/why an error gets returned.
Otherwise the series is fine for me.
Thanks
Philipp
> #ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
> static int kexec_calculate_store_digests(struct kimage *image);
> #else
> static int kexec_calculate_store_digests(struct kimage *image) { return 0; };
> #endif
>
> +int _kexec_kernel_image_probe(struct kimage *image, void *buf,
> + unsigned long buf_len)
> +{
> + const struct kexec_file_ops * const *fops;
> + int ret = -ENOEXEC;
> +
> + for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
> + ret = (*fops)->probe(buf, buf_len);
> + if (!ret) {
> + image->fops = *fops;
> + return ret;
> + }
> + }
> +
> + return ret;
> +}
> +
> /* Architectures can provide this probe function */
> int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> unsigned long buf_len)
> {
> - return -ENOEXEC;
> + return _kexec_kernel_image_probe(image, buf, buf_len);
> +}
> +
> +void *_kexec_kernel_image_load(struct kimage *image)
> +{
> + if (!image->fops || !image->fops->load)
> + return ERR_PTR(-ENOEXEC);
> +
> + return image->fops->load(image, image->kernel_buf,
> + image->kernel_buf_len, image->initrd_buf,
> + image->initrd_buf_len, image->cmdline_buf,
> + image->cmdline_buf_len);
> }
>
> void * __weak arch_kexec_kernel_image_load(struct kimage *image)
> {
> - return ERR_PTR(-ENOEXEC);
> + return _kexec_kernel_image_load(image);
> +}
> +
> +int _kimage_file_post_load_cleanup(struct kimage *image)
> +{
> + if (!image->fops || !image->fops->cleanup)
> + return 0;
> +
> + return image->fops->cleanup(image->image_loader_data);
> }
>
> int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
> {
> - return -EINVAL;
> + return _kimage_file_post_load_cleanup(image);
> }
>
> #ifdef CONFIG_KEXEC_VERIFY_SIG
> +int _kexec_kernel_verify_sig(struct kimage *image, void *buf,
> + unsigned long buf_len)
> +{
> + if (!image->fops || !image->fops->verify_sig) {
> + pr_debug("kernel loader does not support signature verification.\n");
> + return -EKEYREJECTED;
> + }
> +
> + return image->fops->verify_sig(buf, buf_len);
> +}
> +
> int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
> unsigned long buf_len)
> {
> - return -EKEYREJECTED;
> + return _kexec_kernel_verify_sig(image, buf, buf_len);
> }
> #endif
>
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