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? 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". Thanks Philipp > > > > > > > > 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
