On Wed, Feb 23, 2022 at 9:42 AM Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote: > > On Tue, 01 Feb 2022 07:05:40 PST (-0800), guoren@xxxxxxxxxx wrote: > > From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > > > There is no vgettimeofday supported in rv32 that makes simple to > > generate rv32 vdso code which only needs riscv64 compiler. Other > > architectures need change compiler or -m (machine parameter) to > > support vdso32 compiling. If rv32 support vgettimeofday (which > > cause C compile) in future, we would add CROSS_COMPILE to support > > that makes more requirement on compiler enviornment. > > IMO this is the wrong way to go, as there's some subtle differences > between elf32 and elf64 (the .gnu.hash layout, for example). I'm kind > of surprised userspace tolerates this sort of thing at all, but given > how easy it is to target rv32 from all toolchains (we don't need > libraries here, so just -march should do it) I don't think it's worth > chasing around the likely long-tail issues that will arise. I would keep the patch in next version. When "multi-arch toolchain" or "rv32 HAVE_GENERIC_VDSO" isready in the future, let's switch to the rv32 compiler. > > > linux-rv64/arch/riscv/kernel/compat_vdso/compat_vdso.so.dbg: > > file format elf64-littleriscv > > > > Disassembly of section .text: > > > > 0000000000000800 <__vdso_rt_sigreturn>: > > 800: 08b00893 li a7,139 > > 804: 00000073 ecall > > 808: 0000 unimp > > ... > > > > 000000000000080c <__vdso_getcpu>: > > 80c: 0a800893 li a7,168 > > 810: 00000073 ecall > > 814: 8082 ret > > ... > > > > 0000000000000818 <__vdso_flush_icache>: > > 818: 10300893 li a7,259 > > 81c: 00000073 ecall > > 820: 8082 ret > > > > linux-rv32/arch/riscv/kernel/vdso/vdso.so.dbg: > > file format elf32-littleriscv > > > > Disassembly of section .text: > > > > 00000800 <__vdso_rt_sigreturn>: > > 800: 08b00893 li a7,139 > > 804: 00000073 ecall > > 808: 0000 unimp > > ... > > > > 0000080c <__vdso_getcpu>: > > 80c: 0a800893 li a7,168 > > 810: 00000073 ecall > > 814: 8082 ret > > ... > > > > 00000818 <__vdso_flush_icache>: > > 818: 10300893 li a7,259 > > 81c: 00000073 ecall > > 820: 8082 ret > > > > Finally, reuse all *.S from vdso in compat_vdso that makes > > implementation clear and readable. > > > > Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > Signed-off-by: Guo Ren <guoren@xxxxxxxxxx> > > Cc: Arnd Bergmann <arnd@xxxxxxxx> > > Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx> > > --- > > arch/riscv/Makefile | 5 ++ > > arch/riscv/include/asm/vdso.h | 9 +++ > > arch/riscv/kernel/Makefile | 1 + > > arch/riscv/kernel/compat_vdso/.gitignore | 2 + > > arch/riscv/kernel/compat_vdso/Makefile | 68 +++++++++++++++++++ > > arch/riscv/kernel/compat_vdso/compat_vdso.S | 8 +++ > > .../kernel/compat_vdso/compat_vdso.lds.S | 3 + > > arch/riscv/kernel/compat_vdso/flush_icache.S | 3 + > > .../compat_vdso/gen_compat_vdso_offsets.sh | 5 ++ > > arch/riscv/kernel/compat_vdso/getcpu.S | 3 + > > arch/riscv/kernel/compat_vdso/note.S | 3 + > > arch/riscv/kernel/compat_vdso/rt_sigreturn.S | 3 + > > arch/riscv/kernel/vdso/vdso.S | 6 +- > > 13 files changed, 118 insertions(+), 1 deletion(-) > > create mode 100644 arch/riscv/kernel/compat_vdso/.gitignore > > create mode 100644 arch/riscv/kernel/compat_vdso/Makefile > > create mode 100644 arch/riscv/kernel/compat_vdso/compat_vdso.S > > create mode 100644 arch/riscv/kernel/compat_vdso/compat_vdso.lds.S > > create mode 100644 arch/riscv/kernel/compat_vdso/flush_icache.S > > create mode 100755 arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh > > create mode 100644 arch/riscv/kernel/compat_vdso/getcpu.S > > create mode 100644 arch/riscv/kernel/compat_vdso/note.S > > create mode 100644 arch/riscv/kernel/compat_vdso/rt_sigreturn.S > > > > diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile > > index a02e588c4947..f73d50552e09 100644 > > --- a/arch/riscv/Makefile > > +++ b/arch/riscv/Makefile > > @@ -106,12 +106,17 @@ libs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a > > PHONY += vdso_install > > vdso_install: > > $(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso $@ > > + $(if $(CONFIG_COMPAT),$(Q)$(MAKE) \ > > + $(build)=arch/riscv/kernel/compat_vdso $@) > > > > ifeq ($(KBUILD_EXTMOD),) > > ifeq ($(CONFIG_MMU),y) > > prepare: vdso_prepare > > vdso_prepare: prepare0 > > $(Q)$(MAKE) $(build)=arch/riscv/kernel/vdso include/generated/vdso-offsets.h > > + $(if $(CONFIG_COMPAT),$(Q)$(MAKE) \ > > + $(build)=arch/riscv/kernel/compat_vdso include/generated/compat_vdso-offsets.h) > > + > > endif > > endif > > > > diff --git a/arch/riscv/include/asm/vdso.h b/arch/riscv/include/asm/vdso.h > > index bc6f75f3a199..af981426fe0f 100644 > > --- a/arch/riscv/include/asm/vdso.h > > +++ b/arch/riscv/include/asm/vdso.h > > @@ -21,6 +21,15 @@ > > > > #define VDSO_SYMBOL(base, name) \ > > (void __user *)((unsigned long)(base) + __vdso_##name##_offset) > > + > > +#ifdef CONFIG_COMPAT > > +#include <generated/compat_vdso-offsets.h> > > + > > +#define COMPAT_VDSO_SYMBOL(base, name) \ > > + (void __user *)((unsigned long)(base) + compat__vdso_##name##_offset) > > + > > +#endif /* CONFIG_COMPAT */ > > + > > #endif /* !__ASSEMBLY__ */ > > > > #endif /* CONFIG_MMU */ > > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile > > index 954dc7043ad2..88e79f481c21 100644 > > --- a/arch/riscv/kernel/Makefile > > +++ b/arch/riscv/kernel/Makefile > > @@ -67,3 +67,4 @@ obj-$(CONFIG_JUMP_LABEL) += jump_label.o > > > > obj-$(CONFIG_EFI) += efi.o > > obj-$(CONFIG_COMPAT) += compat_syscall_table.o > > +obj-$(CONFIG_COMPAT) += compat_vdso/ > > diff --git a/arch/riscv/kernel/compat_vdso/.gitignore b/arch/riscv/kernel/compat_vdso/.gitignore > > new file mode 100644 > > index 000000000000..19d83d846c1e > > --- /dev/null > > +++ b/arch/riscv/kernel/compat_vdso/.gitignore > > @@ -0,0 +1,2 @@ > > +# SPDX-License-Identifier: GPL-2.0-only > > +compat_vdso.lds > > diff --git a/arch/riscv/kernel/compat_vdso/Makefile b/arch/riscv/kernel/compat_vdso/Makefile > > new file mode 100644 > > index 000000000000..7bbbbf94307f > > --- /dev/null > > +++ b/arch/riscv/kernel/compat_vdso/Makefile > > @@ -0,0 +1,68 @@ > > +# SPDX-License-Identifier: GPL-2.0-only > > + > > +# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before > > +# the inclusion of generic Makefile. > > +ARCH_REL_TYPE_ABS := R_RISCV_32|R_RISCV_64|R_RISCV_JUMP_SLOT > > +include $(srctree)/lib/vdso/Makefile > > +# Symbols present in the compat_vdso > > +compat_vdso-syms = rt_sigreturn > > +compat_vdso-syms += getcpu > > +compat_vdso-syms += flush_icache > > + > > +# Files to link into the compat_vdso > > +obj-compat_vdso = $(patsubst %, %.o, $(compat_vdso-syms)) note.o > > + > > +ccflags-y := -fno-stack-protector > > + > > +# Build rules > > +targets := $(obj-compat_vdso) compat_vdso.so compat_vdso.so.dbg compat_vdso.lds > > +obj-compat_vdso := $(addprefix $(obj)/, $(obj-compat_vdso)) > > + > > +obj-y += compat_vdso.o > > +CPPFLAGS_compat_vdso.lds += -P -C -U$(ARCH) > > + > > +# Disable profiling and instrumentation for VDSO code > > +GCOV_PROFILE := n > > +KCOV_INSTRUMENT := n > > +KASAN_SANITIZE := n > > +UBSAN_SANITIZE := n > > + > > +# Force dependency > > +$(obj)/compat_vdso.o: $(obj)/compat_vdso.so > > + > > +# link rule for the .so file, .lds has to be first > > +$(obj)/compat_vdso.so.dbg: $(obj)/compat_vdso.lds $(obj-compat_vdso) FORCE > > + $(call if_changed,compat_vdsold) > > +LDFLAGS_compat_vdso.so.dbg = -shared -S -soname=linux-compat_vdso.so.1 \ > > + --build-id=sha1 --hash-style=both --eh-frame-hdr > > + > > +# strip rule for the .so file > > +$(obj)/%.so: OBJCOPYFLAGS := -S > > +$(obj)/%.so: $(obj)/%.so.dbg FORCE > > + $(call if_changed,objcopy) > > + > > +# Generate VDSO offsets using helper script > > +gen-compat_vdsosym := $(srctree)/$(src)/gen_compat_vdso_offsets.sh > > +quiet_cmd_compat_vdsosym = VDSOSYM $@ > > + cmd_compat_vdsosym = $(NM) $< | $(gen-compat_vdsosym) | LC_ALL=C sort > $@ > > + > > +include/generated/compat_vdso-offsets.h: $(obj)/compat_vdso.so.dbg FORCE > > + $(call if_changed,compat_vdsosym) > > + > > +# actual build commands > > +# The DSO images are built using a special linker script > > +# Make sure only to export the intended __compat_vdso_xxx symbol offsets. > > +quiet_cmd_compat_vdsold = VDSOLD $@ > > + cmd_compat_vdsold = $(LD) $(ld_flags) -T $(filter-out FORCE,$^) -o $@.tmp && \ > > + $(OBJCOPY) $(patsubst %, -G __compat_vdso_%, $(compat_vdso-syms)) $@.tmp $@ && \ > > + rm $@.tmp > > + > > +# install commands for the unstripped file > > +quiet_cmd_compat_vdso_install = INSTALL $@ > > + cmd_compat_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/compat_vdso/$@ > > + > > +compat_vdso.so: $(obj)/compat_vdso.so.dbg > > + @mkdir -p $(MODLIB)/compat_vdso > > + $(call cmd,compat_vdso_install) > > + > > +compat_vdso_install: compat_vdso.so > > diff --git a/arch/riscv/kernel/compat_vdso/compat_vdso.S b/arch/riscv/kernel/compat_vdso/compat_vdso.S > > new file mode 100644 > > index 000000000000..fea4a8b0c45d > > --- /dev/null > > +++ b/arch/riscv/kernel/compat_vdso/compat_vdso.S > > @@ -0,0 +1,8 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > + > > +#define vdso_start compat_vdso_start > > +#define vdso_end compat_vdso_end > > + > > +#define __VDSO_PATH "arch/riscv/kernel/compat_vdso/compat_vdso.so" > > + > > +#include <../vdso/vdso.S> > > diff --git a/arch/riscv/kernel/compat_vdso/compat_vdso.lds.S b/arch/riscv/kernel/compat_vdso/compat_vdso.lds.S > > new file mode 100644 > > index 000000000000..02a9ec5dc7f6 > > --- /dev/null > > +++ b/arch/riscv/kernel/compat_vdso/compat_vdso.lds.S > > @@ -0,0 +1,3 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > + > > +#include <../vdso/vdso.lds.S> > > diff --git a/arch/riscv/kernel/compat_vdso/flush_icache.S b/arch/riscv/kernel/compat_vdso/flush_icache.S > > new file mode 100644 > > index 000000000000..88e21a84a974 > > --- /dev/null > > +++ b/arch/riscv/kernel/compat_vdso/flush_icache.S > > @@ -0,0 +1,3 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > + > > +#include <../vdso/flush_icache.S> > > diff --git a/arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh b/arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh > > new file mode 100755 > > index 000000000000..8ac070c783b3 > > --- /dev/null > > +++ b/arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh > > @@ -0,0 +1,5 @@ > > +#!/bin/sh > > +# SPDX-License-Identifier: GPL-2.0 > > + > > +LC_ALL=C > > +sed -n -e 's/^[0]\+\(0[0-9a-fA-F]*\) . \(__vdso_[a-zA-Z0-9_]*\)$/\#define compat\2_offset\t0x\1/p' > > diff --git a/arch/riscv/kernel/compat_vdso/getcpu.S b/arch/riscv/kernel/compat_vdso/getcpu.S > > new file mode 100644 > > index 000000000000..946449a15a94 > > --- /dev/null > > +++ b/arch/riscv/kernel/compat_vdso/getcpu.S > > @@ -0,0 +1,3 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > + > > +#include <../vdso/getcpu.S> > > diff --git a/arch/riscv/kernel/compat_vdso/note.S b/arch/riscv/kernel/compat_vdso/note.S > > new file mode 100644 > > index 000000000000..67c50898b8e5 > > --- /dev/null > > +++ b/arch/riscv/kernel/compat_vdso/note.S > > @@ -0,0 +1,3 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > + > > +#include <../vdso/note.S> > > diff --git a/arch/riscv/kernel/compat_vdso/rt_sigreturn.S b/arch/riscv/kernel/compat_vdso/rt_sigreturn.S > > new file mode 100644 > > index 000000000000..f4c98f18c053 > > --- /dev/null > > +++ b/arch/riscv/kernel/compat_vdso/rt_sigreturn.S > > @@ -0,0 +1,3 @@ > > +/* SPDX-License-Identifier: GPL-2.0-only */ > > + > > +#include <../vdso/rt_sigreturn.S> > > diff --git a/arch/riscv/kernel/vdso/vdso.S b/arch/riscv/kernel/vdso/vdso.S > > index df222245be05..83f1c899e8d8 100644 > > --- a/arch/riscv/kernel/vdso/vdso.S > > +++ b/arch/riscv/kernel/vdso/vdso.S > > @@ -7,12 +7,16 @@ > > #include <linux/linkage.h> > > #include <asm/page.h> > > > > +#ifndef __VDSO_PATH > > +#define __VDSO_PATH "arch/riscv/kernel/vdso/vdso.so" > > +#endif > > + > > __PAGE_ALIGNED_DATA > > > > .globl vdso_start, vdso_end > > .balign PAGE_SIZE > > vdso_start: > > - .incbin "arch/riscv/kernel/vdso/vdso.so" > > + .incbin __VDSO_PATH > > .balign PAGE_SIZE > > vdso_end: -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/
