Hi Philipp, On 03/20/18 at 10:39am, Philipp Rudo wrote: > Hi Dave, > > sorry for the late answer. > > > On Fri, 16 Mar 2018 14:41:02 +0800 > Dave Young <dyoung@xxxxxxxxxx> wrote: > > > On 03/15/18 at 11:13am, Philipp Rudo wrote: > > > Hi Dave, > > > > > > On Thu, 15 Mar 2018 15:34:22 +0800 > > > Dave Young <dyoung@xxxxxxxxxx> wrote: > > > > > > > On 03/12/18 at 03:40pm, Dave Young wrote: > > > > > Hi Philipp, > > > > > On 03/09/18 at 03:25pm, Philipp Rudo wrote: > > > > > > Hi Dave, > > > > > > > > > > > > On Fri, 9 Mar 2018 13:19:40 +0800 > > > > > > Dave Young <dyoung@xxxxxxxxxx> wrote: > > > > > > > > > > > > > Hi Philipp, > > > > > > > On 02/26/18 at 04:16pm, Philipp Rudo wrote: > > > > > > > > > > > > > > > > Hi everybody > > > > > > > > > > > > > > > > following the discussion with Dave and AKASHI, here are the common code > > > > > > > > patches extracted from my recent patch set (Add kexec_file_load support to > > > > > > > > s390) [1]. The patches were extracted to allow upstream integration together > > > > > > > > with AKASHI's common code patches before the arch code gets adjusted to the > > > > > > > > new base. > > > > > > > > > > > > > > > > The reason for this series is to prepare common code for adding > > > > > > > > kexec_file_load to s390 as well as cleaning up the mis-use of the sh_offset > > > > > > > > field during purgatory load. In detail this series contains: > > > > > > > > > > > > > > > > Patch #1&2: Minor cleanups/fixes. > > > > > > > > > > > > > > > > Patch #3-9: Clean up the purgatory load/relocation code. Especially remove > > > > > > > > the mis-use of the purgatory_info->sechdrs->sh_offset field, currently > > > > > > > > holding a pointer into either kexec_purgatory (ro) or purgatory_buf (rw) > > > > > > > > depending on the section. With these patches the section address will be > > > > > > > > calculated verbosely and sh_offset will contain the offset of the section > > > > > > > > in the stripped purgatory binary (purgatory_buf). > > > > > > > > > > > > > > > > Patch #10: Allows architectures to set the purgatory load address. This > > > > > > > > patch is important for s390 as the kernel and purgatory have to be loaded > > > > > > > > to fixed addresses. In current code this is impossible as the purgatory > > > > > > > > load is opaque to the architecture. > > > > > > > > > > > > > > > > Patch #11: Moves x86 purgatories sha implementation to common lib/ > > > > > > > > directory to allow reuse in other architectures. > > > > > > > > > > > > > > > > The patches apply to v4.16-rc3. There are no changes compared to [1] (all > > > > > > > > requested changes only affected s390 code). Please note that I had to touch > > > > > > > > arch code for x86 and power a little. In theory this should not change the > > > > > > > > behavior but I don't have a way to test it. Cross-compiling with > > > > > > > > defconfig [2] works fine for both. > > > > > > > > > > > > > > > > Thanks > > > > > > > > Philipp > > > > > > > > > > > > > > > > [1] http://lists.infradead.org/pipermail/kexec/2018-February/019926.html > > > > > > > > [2] On x86 with the orc unwinder and stack validation turned off. objtool > > > > > > > > SEGFAULTs on s390... > > > > > > > > > > > > > > > > Philipp Rudo (11): > > > > > > > > kexec_file: Silence compile warnings > > > > > > > > kexec_file: Remove checks in kexec_purgatory_load > > > > > > > > kexec_file: Make purgatory_info->ehdr const > > > > > > > > kexec_file: Search symbols in read-only kexec_purgatory > > > > > > > > kexec_file: Use read-only sections in arch_kexec_apply_relocations* > > > > > > > > kexec_file: Split up __kexec_load_puragory > > > > > > > > kexec_file: Simplify kexec_purgatory_setup_sechdrs 1 > > > > > > > > kexec_file: Simplify kexec_purgatory_setup_sechdrs 2 > > > > > > > > kexec_file: Remove mis-use of sh_offset field > > > > > > > > kexec_file: Allow archs to set purgatory load address > > > > > > > > kexec_file: Move purgatories sha256 to common code > > > > > > > > > > > > > > > > arch/powerpc/kernel/kexec_elf_64.c | 9 +- > > > > > > > > arch/x86/kernel/kexec-bzimage64.c | 8 +- > > > > > > > > arch/x86/kernel/machine_kexec_64.c | 66 ++--- > > > > > > > > arch/x86/purgatory/Makefile | 3 + > > > > > > > > arch/x86/purgatory/purgatory.c | 2 +- > > > > > > > > include/linux/kexec.h | 38 +-- > > > > > > > > {arch/x86/purgatory => include/linux}/sha256.h | 10 +- > > > > > > > > kernel/kexec_file.c | 375 ++++++++++++------------- > > > > > > > > {arch/x86/purgatory => lib}/sha256.c | 4 +- > > > > > > > > 9 files changed, 244 insertions(+), 271 deletions(-) > > > > > > > > rename {arch/x86/purgatory => include/linux}/sha256.h (63%) > > > > > > > > rename {arch/x86/purgatory => lib}/sha256.c (99%) > > > > > > > > > > > > > > > > -- > > > > > > > > 2.13.5 > > > > > > > > > > > > > > > > > > > > > > I did a test on x86, but it failed: > > > > > > > [ 15.636489] kexec: Undefined symbol: memcpy > > > > > > > [ 15.636496] kexec-bzImage64: Loading purgatory failed > > > > > > > [ 33.603356] kexec: Undefined symbol: memcpy > > > > > > > [ 33.603362] kexec-bzImage64: Loading purgatory failed > > > > > > > > > > > > > > I think this relates to the sha256 splitting patch. > > > > > > > > > > > > I looked into this a little closer and i think i understood what happens. > > > > > > > > > > > > There is no definition of memcpy in arch/x86/boot/string.c, instead it's defined > > > > > > in arch/x86/boot/string.h as __buildin_memcpy (same for memset). Thus by > > > > > > switching to linux/string.h there is no more definition for it. Leaving us with > > > > > > > > > > > > $ readelf -s purgatory.ro > > > > > > [...] > > > > > > 45: 0000000000000000 0 NOTYPE GLOBAL DEFAULT UND memcpy > > > > > > [...] > > > > > > > > > > > > To solve this problem I see two possibilities (example patches are at the end of > > > > > > the mail): > > > > > > > > > > > > 1) Have arch dependent includes in lib/sha256.c > > > > > > 2) Add makefile magic so memcpy is defined > > > > > > > > > > > > With both solutions the resulting purgatory.ro looks good. However both > > > > > > solutions aren't perfect. For example in 2) i had too mix the linux/string.h > > > > > > header with arch/x86/boot/string.c, because lib/string.c has too many > > > > > > dependencies and does not compile in the purgatory. On the other hand having > > > > > > arch dependent includes isn't that nice either ... > > > > > > > > > > > > What's your opinion on this? > > > > > > > > > > Looks like it is a mess, maybe the 1st one is better although it is also > > > > > ugly. Ccing Ingo see if he has some idea about this. > > > > > > > > Maybe something like below is better if no other idea: > > > > > > > > diff --git a/arch/x86/boot/string_builtin.c b/arch/x86/boot/string_builtin.c > > > > new file mode 100644 > > > > index 000000000000..9099f949fb41 > > > > --- /dev/null > > > > +++ b/arch/x86/boot/string_builtin.c > > > > @@ -0,0 +1,11 @@ > > > > +#include <linux/types.h> > > > > + > > > > +void *memcpy(void *dst, const void *src, size_t len) > > > > +{ > > > > + return __builtin_memcpy(dst, src, len); > > > > +} > > > > + > > > > +void *memset(void *dst, int c, size_t len) > > > > +{ > > > > + return __builtin_memset(dst, c, len); > > > > +} > > > > diff --git a/arch/x86/purgatory/string.c b/arch/x86/purgatory/string.c > > > > index d886b1fa36f0..e12c78fcd59f 100644 > > > > --- a/arch/x86/purgatory/string.c > > > > +++ b/arch/x86/purgatory/string.c > > > > @@ -11,3 +11,4 @@ > > > > */ > > > > > > > > #include "../boot/string.c" > > > > +#include "../boot/string_builtin.c" > > > > > > Looks like a good idea to me. Just to be sure, with this suggestion > > > lib/sha256.c stays unchanged, i.e. it includes linux/string.h? > > > > Yes, I assumed so, one thing is I noticed linux/string.h uses __kernel_size_t, but > > the boot/string.h use _size_t. > > I don't think the __kernel_size_t vs. _size_t is a problem. When I make gcc's > intermediate file > > $ make /arch/x86/purgatory/string.i > > the type doesn't change with and without my patches. In both cases size_t is > defined as > > size_t -> __kernel_size_t -> __kernel_ulong_t -> unsigned long > > So (at least for now) we are safe. > > > > > > > The only thing I don't really like is adding the extra boot/string.builtin.c > > > file. For my taste adding the two functions directly to purgatory/string.c would > > > be nicer. However in the end it's "not my problem". > > > > string.c is also included in boot/compressed/string.c which defines its > > own version of memcpy. And in the boot/compressed/string.c version it > > calls warn() which is a special function for decompressor used only. > > I'm not sure how to merge them with one string.c now. > > That's why i suggested to put the two functions into _purgatory_/string.c. In > the end the file would read > > --- > $ cat arch/x86/purgatory/string.c > /* > * Simple string functions. > * > * Copyright (C) 2014 Red Hat Inc. > * > * Author: > * Vivek Goyal <vgoyal@xxxxxxxxxx> > * > * This source code is licensed under the GNU General Public License, > * Version 2. See the file COPYING for more details. > */ > > #include <linux/types.h> > > #include "../boot/string.c" > > void *memcpy(void *dst, const void *src, size_t len) > { > return __builtin_memcpy(dst, src, len); > } > > void *memset(void *dst, int c, size_t len) > { > return __builtin_memset(dst, c, len); > } > --- > > Of course it would be even nicer having them in boot/string.c. But as you > already mentioned that would require a larger cleanup and should be done by > somebody with more experience on x86. Ok, I got your points, your proposal looks good to me if no better choice. Thanks Dave -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
