Hi Akashi, On 04/12/17 02:57, AKASHI Takahiro wrote: > This is a basic purgatory, or a kind of glue code between the two kernels, > for arm64. > > Since purgatory is assumed to be relocatable (not executable) object by > kexec generic code, arch_kexec_apply_relocations_add() is required in > general. Arm64's purgatory, however, is a simple asm and all the references > can be resolved as local, no re-linking is needed here. > > Please note that even if we don't support digest check at purgatory we (You knew what I was going to ask!) > need purgatory_sha_regions and purgatory_sha256_digest as they are > referenced by generic kexec code. As somewhere to store the values? If we aren't doing the validation could we add something about why not to the commit message? I think its because we only worry about memory corruption for kdump, and for kdump we unmap the crash-kernel region during normal-operation to prevent it getting corrupted. As we aren't doing the hash validation, could we hide its core-code behind some ARCH_HAS_KEXEC_PURGATORY_HASH, instead of defining dummy symbols and doing unnecessary work to fill them in? > diff --git a/arch/arm64/purgatory/entry.S b/arch/arm64/purgatory/entry.S > new file mode 100644 > index 000000000000..fe6e968076db > --- /dev/null > +++ b/arch/arm64/purgatory/entry.S > @@ -0,0 +1,55 @@ > +/* > + * kexec core purgatory > + */ > +#include <linux/linkage.h> > +#include <uapi/linux/kexec.h> > + > +#define SHA256_DIGEST_SIZE 32 /* defined in crypto/sha.h */ > + > +.text > + > +ENTRY(purgatory_start) > + /* Start new image. */ > + ldr x17, __kernel_entry > + ldr x0, __dtb_addr > + mov x1, xzr > + mov x2, xzr > + mov x3, xzr > + br x17 > +END(purgatory_start) Is this what arm64_relocate_new_kernel() drops into? I thought that had the kernel boot register values already so we wouldn't need another trampoline for kexec_file_load()... .. but now that I look, it doesn't have the DTB, presumably because for regular kexec we don't know where user-space put it. Could we add some x0_for_kexec that is 0 by default (if that's the ABI), or the DTB address for kexec_file_load()? This would avoid this extra trampoline, and patching in the values from load_other_segments(). I'd love to avoid an in-kernel purgatory! (its code with funny compile/link/relocation requirements that is impossible to debug) Thanks, James _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
