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. > > Thanks > Philipp > > ----- > Example solution 1 > > --- a/lib/sha256.c > +++ b/lib/sha256.c > @@ -17,9 +17,14 @@ > > #include <linux/bitops.h> > #include <linux/sha256.h> > -#include <linux/string.h> > #include <asm/byteorder.h> > > +#ifdef CONFIG_X86 > +#include "../arch/x86/boot/string.h" > +#else > +#include <linux/string.h> > +#endif /* CONFIG_X86 */ > + > static inline u32 Ch(u32 x, u32 y, u32 z) > { > return z ^ (x & (y ^ z)); > > ----- > Example solution 2 > > --- a/arch/x86/purgatory/Makefile > +++ b/arch/x86/purgatory/Makefile > @@ -1,7 +1,8 @@ > # SPDX-License-Identifier: GPL-2.0 > OBJECT_FILES_NON_STANDARD := y > > -purgatory-y := purgatory.o stack.o setup-x86_$(BITS).o sha256.o entry64.o string.o > +purgatory-y := purgatory.o stack.o setup-x86_$(BITS).o sha256.o entry64.o \ > + string.o memcpy_$(BITS).o memset_$(BITS).o > > targets += $(purgatory-y) > PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y)) > @@ -9,6 +10,15 @@ PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y)) > $(obj)/sha256.o: $(srctree)/lib/sha256.c > $(call if_changed_rule,cc_o_c) > > +$(obj)/string.o: $(srctree)/arch/x86/boot/string.c > + $(call if_changed_rule,cc_o_c) > + > +$(obj)/memset_$(BITS).o: $(srctree)/arch/x86/lib/memset_$(BITS).S > + $(call if_changed_rule,as_o_S) > + > +$(obj)/memcpy_$(BITS).o: $(srctree)/arch/x86/lib/memcpy_$(BITS).S > + $(call if_changed_rule,as_o_S) > + > LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined -nostdlib -z nodefaultlib > targets += purgatory.ro > > 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
