Date:   Fri, 25 Feb 2022 23:42:09 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Anup Patel <anup@...infault.org>,
        gregkh <gregkh@...uxfoundation.org>,
        liush <liush@...winnertech.com>, Wei Fu <wefu@...hat.com>,
        Drew Fustini <drew@...gleboard.org>,
        Wang Junqiang <wangjunqiang@...as.ac.cn>,
        Christoph Hellwig <hch@....de>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        linux-csky@...r.kernel.org,
        linux-s390 <linux-s390@...r.kernel.org>,
        sparclinux <sparclinux@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Parisc List <linux-parisc@...r.kernel.org>,
        "open list:BROADCOM NVRAM DRIVER" <linux-mips@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Guo Ren <guoren@...ux.alibaba.com>
Subject: Re: [PATCH V6 16/20] riscv: compat: vdso: Add rv32 VDSO base code implementation

Hi Arnd & Palmer,

Here is the new modified compat_vdso/Makefile, please have a look,
first. Then I would update it to v7:
===========================================
# SPDX-License-Identifier: GPL-2.0-only
#
# Makefile for compat_vdso
#

# Symbols present in the compat_vdso
compat_vdso-syms  = rt_sigreturn
compat_vdso-syms += getcpu
compat_vdso-syms += flush_icache

ifdef CROSS_COMPILE_COMPAT
        COMPAT_CC := $(CROSS_COMPILE_COMPAT)gcc
        COMPAT_LD := $(CROSS_COMPILE_COMPAT)ld
else
        COMPAT_CC := $(CC)
        COMPAT_LD := $(LD)
endif

COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
COMPAT_LD_FLAGS := -melf32lriscv

# Files to link into the compat_vdso
obj-compat_vdso = $(patsubst %, %.o, $(compat_vdso-syms)) note.o

# 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

$(obj-compat_vdso): %.o: %.S FORCE
        $(call if_changed_dep,compat_vdsoas)

# 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 = $(COMPAT_LD) $(ld_flags) $(COMPAT_LD_FLAGS)
-T $(filter-out FORCE,$^) -o $@...p && \
                   $(OBJCOPY) $(patsubst %, -G __compat_vdso_%,
$(compat_vdso-syms)) $@...p $@ && \
                   rm $@...p

# actual build commands
quiet_cmd_compat_vdsoas = VDSOAS $@
      cmd_compat_vdsoas = $(COMPAT_CC) $(a_flags) $(COMPAT_CC_FLAGS) -c -o $@ $<

# install commands for the unstripped file
quiet_cmd_compat_vdso_install = INSTALL $@
      cmd_compat_vdso_install = cp $(obj)/$@...g $(MODLIB)/compat_vdso/$@

compat_vdso.so: $(obj)/compat_vdso.so.dbg
        @mkdir -p $(MODLIB)/compat_vdso
        $(call cmd,compat_vdso_install)

compat_vdso_install: compat_vdso.so
===========================================

Here is the make V=1 output:

make -f /home/guoren/source/kernel/riscv-linux/scripts/Makefile.build
obj=arch/riscv/kernel/vdso include/generated/vdso-offsets.h
make -f /home/guoren/source/kernel/riscv-linux/scripts/Makefile.build
obj=arch/riscv/kernel/compat_vdso
include/generated/compat_vdso-offsets.h
  riscv64-unknown-linux-gnu-gcc -E
-Wp,-MMD,arch/riscv/kernel/compat_vdso/.compat_vdso.lds.d  -nostdinc
-I/home/guoren/source/kernel/riscv-linux/arch/riscv/include
-I./arch/riscv/include/generated
-I/home/guoren/source/kernel/riscv-linux/include -I./include
-I/home/guoren/source/kernel/riscv-linux/arch/riscv/include/uapi
-I./arch/riscv/include/generated/uapi
-I/home/guoren/source/kernel/riscv-linux/include/uapi -I./includ
e/generated/uapi -include
/home/guoren/source/kernel/riscv-linux/include/linux/compiler-version.h
-include /home/guoren/source/kernel/riscv-linux/include/linux/kconfig.h
-D__KERNEL__ -fmacro-prefix-map=/home/guoren/source/kernel/riscv-linux/=
   -P -C -Uriscv -I
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso
-I ./arch/riscv/kernel/compat_vdso -P -Uriscv -D__ASSEMBLY__
-DLINKER_SCRIPT -o arch/riscv/ke
rnel/compat_vdso/compat_vdso.lds
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso/compat_vdso.lds.S
  riscv64-unknown-linux-gnu-gcc
-Wp,-MMD,arch/riscv/kernel/compat_vdso/.rt_sigreturn.o.d  -nostdinc
-I/home/guoren/source/kernel/riscv-linux/arch/riscv/include
-I./arch/riscv/include/generated
-I/home/guoren/source/kernel/riscv-linux/include -I./include
-I/home/guoren/source/kernel/riscv-linux/arch/riscv/include/uapi
-I./arch/riscv/include/generated/uapi
-I/home/guoren/source/kernel/riscv-linux/include/uapi -I./include/ge
nerated/uapi -include
/home/guoren/source/kernel/riscv-linux/include/linux/compiler-version.h
-include /home/guoren/source/kernel/riscv-linux/include/linux/kconfig.h
-D__KERNEL__ -fmacro-prefix-map=/home/guoren/source/kernel/riscv-linux/=
-D__ASSEMBLY__ -fno-PIE -mabi=lp64 -march=rv64imafdc -I
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso
-I ./arch/riscv/kernel/compat_vdso    -march=rv32g -mabi=ilp3
2 -c -o arch/riscv/kernel/compat_vdso/rt_sigreturn.o
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso/rt_sigreturn.S
  riscv64-unknown-linux-gnu-gcc
-Wp,-MMD,arch/riscv/kernel/compat_vdso/.getcpu.o.d  -nostdinc
-I/home/guoren/source/kernel/riscv-linux/arch/riscv/include
-I./arch/riscv/include/generated
-I/home/guoren/source/kernel/riscv-linux/include -I./include
-I/home/guoren/source/kernel/riscv-linux/arch/riscv/include/uapi
-I./arch/riscv/include/generated/uapi
-I/home/guoren/source/kernel/riscv-linux/include/uapi
-I./include/generate
d/uapi -include
/home/guoren/source/kernel/riscv-linux/include/linux/compiler-version.h
-include /home/guoren/source/kernel/riscv-linux/include/linux/kconfig.h
-D__KERNEL__ -fmacro-prefix-map=/home/guoren/source/kernel/riscv-linux/=
-D__ASSEMBLY__ -fno-PIE -mabi=lp64 -march=rv64imafdc -I
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso
-I ./arch/riscv/kernel/compat_vdso    -march=rv32g -mabi=ilp32 -c -
o arch/riscv/kernel/compat_vdso/getcpu.o
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso/getcpu.S
  riscv64-unknown-linux-gnu-gcc
-Wp,-MMD,arch/riscv/kernel/compat_vdso/.flush_icache.o.d  -nostdinc
-I/home/guoren/source/kernel/riscv-linux/arch/riscv/include
-I./arch/riscv/include/generated
-I/home/guoren/source/kernel/riscv-linux/include -I./include
-I/home/guoren/source/kernel/riscv-linux/arch/riscv/include/uapi
-I./arch/riscv/include/generated/uapi
-I/home/guoren/source/kernel/riscv-linux/include/uapi -I./include/ge
nerated/uapi -include
/home/guoren/source/kernel/riscv-linux/include/linux/compiler-version.h
-include /home/guoren/source/kernel/riscv-linux/include/linux/kconfig.h
-D__KERNEL__ -fmacro-prefix-map=/home/guoren/source/kernel/riscv-linux/=
-D__ASSEMBLY__ -fno-PIE -mabi=lp64 -march=rv64imafdc -I
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso
-I ./arch/riscv/kernel/compat_vdso    -march=rv32g -mabi=ilp3
2 -c -o arch/riscv/kernel/compat_vdso/flush_icache.o
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso/flush_icache.S
  riscv64-unknown-linux-gnu-gcc
-Wp,-MMD,arch/riscv/kernel/compat_vdso/.note.o.d  -nostdinc
-I/home/guoren/source/kernel/riscv-linux/arch/riscv/include
-I./arch/riscv/include/generated
-I/home/guoren/source/kernel/riscv-linux/include -I./include
-I/home/guoren/source/kernel/riscv-linux/arch/riscv/include/uapi
-I./arch/riscv/include/generated/uapi
-I/home/guoren/source/kernel/riscv-linux/include/uapi
-I./include/generated/
uapi -include /home/guoren/source/kernel/riscv-linux/include/linux/compiler-version.h
-include /home/guoren/source/kernel/riscv-linux/include/linux/kconfig.h
-D__KERNEL__ -fmacro-prefix-map=/home/guoren/source/kernel/riscv-linux/=
-D__ASSEMBLY__ -fno-PIE -mabi=lp64 -march=rv64imafdc -I
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso
-I ./arch/riscv/kernel/compat_vdso    -march=rv32g -mabi=ilp32 -c -o
arch/riscv/kernel/compat_vdso/note.o
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso/note.S
  riscv64-unknown-linux-gnu-ld  -melf64lriscv   -shared -S
-soname=linux-compat_vdso.so.1 --build-id=sha1 --hash-style=both
--eh-frame-hdr -melf32lriscv -T
arch/riscv/kernel/compat_vdso/compat_vdso.lds
arch/riscv/kernel/compat_vdso/rt_sigreturn.o
arch/riscv/kernel/compat_vdso/getcpu.o
arch/riscv/kernel/compat_vdso/flush_icache.o
arch/riscv/kernel/compat_vdso/note.o -o
arch/riscv/kernel/compat_vdso/compat_vdso.so.dbg.tmp &
& riscv64-unknown-linux-gnu-objcopy  -G __compat_vdso_rt_sigreturn  -G
__compat_vdso_getcpu  -G __compat_vdso_flush_icache
arch/riscv/kernel/compat_vdso/compat_vdso.so.dbg.tmp
arch/riscv/kernel/compat_vdso/compat_vdso.so.dbg && rm
arch/riscv/kernel/compat_vdso/compat_vdso.so.dbg.tmp
  riscv64-unknown-linux-gnu-nm
arch/riscv/kernel/compat_vdso/compat_vdso.so.dbg |
/home/guoren/source/kernel/riscv-linux/arch/riscv/kernel/compat_vdso/gen_compat_vdso_offsets.sh
| LC_ALL=C sort > include/generated/compat_vdso-offsets.h


On Thu, Feb 24, 2022 at 6:13 PM Arnd Bergmann <arnd@...db.de> wrote:
>
> On Thu, Feb 24, 2022 at 9:54 AM <guoren@...nel.org> wrote:
> >
> > From: Guo Ren <guoren@...ux.alibaba.com>
> >
> > 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.
>
> I think it's just a bug that rv32 doesn't have the vdso version of the
> time syscalls. Fixing that is of course independent of the compat support,
> but I think you need that anyway, and it would be better to start
> out by building the compat vdso with the correct
> architecture level.
>
> At least this should be a lot easier than on arch/arm64 because you
> can assume that an rv64 compiler is able to also build rv32 output.
>
>         Arnd



-- 
Best Regards
 Guo Ren

ML: https://lore.kernel.org/linux-csky/

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