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Running "make" on an already compiled kernel tree will rebuild the
kernel even without any modifications:
CALL linux/scripts/checksyscalls.sh
CALL linux/scripts/atomic/check-atomics.sh
CHK include/generated/compile.h
SO2S arch/riscv/kernel/vdso/vdso-syms.S
AS arch/riscv/kernel/vdso/vdso-syms.o
AR arch/riscv/kernel/vdso/built-in.a
AR arch/riscv/kernel/built-in.a
AR arch/riscv/built-in.a
GEN .version
CHK include/generated/compile.h
UPD include/generated/compile.h
CC init/version.o
AR init/built-in.a
LD vmlinux.o
The reason is "Any target that utilizes if_changed must be listed in
$(targets), otherwise the command line check will fail, and the target
will always be built" as explained by Documentation/kbuild/makefiles.rst
Fix this build bug by adding vdso-syms.S to $(targets)
At the same time, there are two trivial clean up modifications:
- the vdso-dummy.o is not needed any more after so remove it.
- vdso.lds is a generated file, so it should be prefixed with
$(obj)/ instead of $(src)/
Fixes: c2c81bb2f691 ("RISC-V: Fix the VDSO symbol generaton for binutils-2.35+")
Cc: stable@vger.kernel.org
Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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Currently, the VDSO is being linked through $(CC). This does not match
how the rest of the kernel links objects, which is through the $(LD)
variable.
When linking with clang, there are a couple of warnings about flags that
will not be used during the link:
clang-12: warning: argument unused during compilation: '-no-pie' [-Wunused-command-line-argument]
clang-12: warning: argument unused during compilation: '-pg' [-Wunused-command-line-argument]
'-no-pie' was added in commit 85602bea297f ("RISC-V: build vdso-dummy.o
with -no-pie") to override '-pie' getting added to the ld command from
distribution versions of GCC that enable PIE by default. It is
technically no longer needed after commit c2c81bb2f691 ("RISC-V: Fix the
VDSO symbol generaton for binutils-2.35+"), which removed vdso-dummy.o
in favor of generating vdso-syms.S from vdso.so with $(NM) but this also
resolves the issue in case it ever comes back due to having full control
over the $(LD) command. '-pg' is for function tracing, it is not used
during linking as clang states.
These flags could be removed/filtered to fix the warnings but it is
easier to just match the rest of the kernel and use $(LD) directly for
linking. See commits
fe00e50b2db8 ("ARM: 8858/1: vdso: use $(LD) instead of $(CC) to link VDSO")
691efbedc60d ("arm64: vdso: use $(LD) instead of $(CC) to link VDSO")
2ff906994b6c ("MIPS: VDSO: Use $(LD) instead of $(CC) to link VDSO")
2b2a25845d53 ("s390/vdso: Use $(LD) instead of $(CC) to link vDSO")
for more information.
The flags are converted to linker flags and '--eh-frame-hdr' is added to
match what is added by GCC implicitly, which can be seen by adding '-v'
to GCC's invocation.
Additionally, since this area is being modified, use the $(OBJCOPY)
variable instead of an open coded $(CROSS_COMPILE)objcopy so that the
user's choice of objcopy binary is respected.
Link: https://github.com/ClangBuiltLinux/linux/issues/803
Link: https://github.com/ClangBuiltLinux/linux/issues/970
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Fangrui Song <maskray@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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We use the generic C VDSO implementations of a handful of clock-related
functions. When kasan is enabled this results in asan stub calls that
are unlikely to be resolved by userspace, this just disables KASAN
when building the VDSO.
Verified the fix on a kernel with KASAN enabled using vDSO selftests.
Link: https://lore.kernel.org/lkml/CACT4Y+ZNJBnkKHXUf=tm_yuowvZvHwN=0rmJ=7J+xFd+9r_6pQ@mail.gmail.com/
Tested-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
[Palmer: commit text]
Fixes: ad5d1122b82f ("riscv: use vDSO common flow to reduce the latency of the time-related functions")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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Commit a96843372331 ("kbuild: explicitly specify the build id style")
explicitly set the build ID style to SHA1. Commit c2c81bb2f691 ("RISC-V:
Fix the VDSO symbol generaton for binutils-2.35+") undid this change,
likely unintentionally.
Restore it so that the build ID style stays consistent across the tree
regardless of linker.
Fixes: c2c81bb2f691 ("RISC-V: Fix the VDSO symbol generaton for binutils-2.35+")
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Bill Wendling <morbo@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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We were relying on GNU ld's ability to re-link executable files in order
to extract our VDSO symbols. This behavior was deemed a bug as of
binutils-2.35 (specifically the binutils-gdb commit a87e1817a4 ("Have
the linker fail if any attempt to link in an executable is made."), but
as that has been backported to at least Debian's binutils-2.34 in may
manifest in other places.
The previous version of this was a bit of a mess: we were linking a
static executable version of the VDSO, containing only a subset of the
input symbols, which we then linked into the kernel. This worked, but
certainly wasn't a supported path through the toolchain. Instead this
new version parses the textual output of nm to produce a symbol table.
Both rely on near-zero addresses being linkable, but as we rely on weak
undefined symbols being linkable elsewhere I don't view this as a major
issue.
Fixes: e2c0cdfba7f6 ("RISC-V: User-facing API")
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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ld's --build-id defaults to "sha1" style, while lld defaults to "fast".
The build IDs are very different between the two, which may confuse
programs that reference them.
Signed-off-by: Bill Wendling <morbo@google.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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Currently, building the vDSO with clang leads assembler errors like the
following:
/tmp/vgettimeofday-1ae0d2.s: Assembler messages:
/tmp/vgettimeofday-1ae0d2.s:28: Error: bad expression
/tmp/vgettimeofday-1ae0d2.s:28: Error: illegal operands `auipc a2,%got_pcrel_hi(__stack_chk_guard)'
Disable the stack-protector for vDSO to fix these.
Link: https://github.com/ClangBuiltLinux/linux/issues/1112
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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Add ARCH_HAS_KCOV and HAVE_GCC_PLUGINS to the riscv Kconfig.
Also disable instrumentation of some early boot code and vdso.
Boot-tested on QEMU's riscv64 virt machine.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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For linux-5.8-rc1, enable ftrace of riscv will cause boot panic:
[ 2.388980] Run /sbin/init as init process
[ 2.529938] init[39]: unhandled signal 4 code 0x1 at 0x0000003ff449e000
[ 2.531078] CPU: 0 PID: 39 Comm: init Not tainted 5.8.0-rc1-dirty #13
[ 2.532719] epc: 0000003ff449e000 ra : 0000003ff449e954 sp : 0000003fffedb900
[ 2.534005] gp : 00000000000e8528 tp : 0000003ff449d800 t0 : 000000000000001e
[ 2.534965] t1 : 000000000000000a t2 : 0000003fffedb89e s0 : 0000003fffedb920
[ 2.536279] s1 : 0000003fffedb940 a0 : 0000003ff43d4b2c a1 : 0000000000000000
[ 2.537334] a2 : 0000000000000001 a3 : 0000000000000000 a4 : fffffffffbad8000
[ 2.538466] a5 : 0000003ff449e93a a6 : 0000000000000000 a7 : 0000000000000000
[ 2.539511] s2 : 0000000000000000 s3 : 0000003ff448412c s4 : 0000000000000010
[ 2.541260] s5 : 0000000000000016 s6 : 00000000000d0a30 s7 : 0000003fffedba70
[ 2.542152] s8 : 0000000000000000 s9 : 0000000000000000 s10: 0000003fffedb960
[ 2.543335] s11: 0000000000000000 t3 : 0000000000000000 t4 : 0000003fffedb8a0
[ 2.544471] t5 : 0000000000000000 t6 : 0000000000000000
[ 2.545730] status: 0000000000004020 badaddr: 00000000464c457f cause: 0000000000000002
[ 2.549867] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004
[ 2.551267] CPU: 0 PID: 1 Comm: init Not tainted 5.8.0-rc1-dirty #13
[ 2.552061] Call Trace:
[ 2.552626] [<ffffffe00020374a>] walk_stackframe+0x0/0xc4
[ 2.553486] [<ffffffe0002039f4>] show_stack+0x40/0x4c
[ 2.553995] [<ffffffe00054a6ae>] dump_stack+0x7a/0x98
[ 2.554615] [<ffffffe00020b9b8>] panic+0x114/0x2f4
[ 2.555395] [<ffffffe00020ebd6>] do_exit+0x89c/0x8c2
[ 2.555949] [<ffffffe00020f930>] do_group_exit+0x3a/0x90
[ 2.556715] [<ffffffe000219e08>] get_signal+0xe2/0x6e6
[ 2.557388] [<ffffffe000202d72>] do_notify_resume+0x6a/0x37a
[ 2.558089] [<ffffffe000201c16>] ret_from_exception+0x0/0xc
"ra:0x3ff449e954" is the return address of "call _mcount" in the
prologue of __vdso_gettimeofday(). Without proper relocate, pc jmp
to 0x0000003ff449e000 (vdso map base) with a illegal instruction
trap.
The solution comes from arch/arm64/kernel/vdso/Makefile:
CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS)
- CC_FLAGS_SCS is ShadowCallStack feature in Clang and only
implemented for arm64, no use for riscv.
Fixes: ad5d1122b82f ("riscv: use vDSO common flow to reduce the latency of the time-related functions")
Cc: stable@vger.kernel.org
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Reviewed-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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Add extern declarations for vDSO time-related functions to notify the
compiler these functions will be used in somewhere to avoid
"no previous prototype" compile warning.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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The time related vDSO functions use a variable, vdso_data, to access the
vDSO data page to get the system time information. Because the vdso_data
for CFLAGS_vgettimeofday.o is an external variable defined in vdso.o,
the CFLAGS_vgettimeofday.o should be compiled with -fPIC to ensure
that vdso_data is addressable.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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Even if RISC-V has supported the vDSO feature, the latency of the functions
for obtaining the system time is still expensive. It is because these
functions still trigger a corresponding system call in the process, which
slows down the response time. If we want to remove the system call to
reduce the latency, the kernel should have the ability to output the system
clock information to userspace. This patch introduces the vDSO common flow
to enable the kernel to achieve the above feature and uses "rdtime"
instruction to obtain the current time in the user space. Under this
condition, the latency cost by the ecall from U-mode to S-mode can be
eliminated. After applying this patch, the latency of gettimeofday()
measured on the HiFive unleashed board can be reduced by %61.
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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The Linux note in the vdso allows glibc to check the running kernel
version without having to issue the uname syscall.
Signed-off-by: Andreas Schwab <schwab@suse.de>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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When building with the LLVM linker this error occurrs:
LD arch/riscv/kernel/vdso/vdso-syms.o
ld.lld: error: no input files
This happens because the lld treats -R as an alias to -rpath, as opposed
to ld where -R means --just-symbols.
Use the long option name for compatibility between the two.
Link: https://github.com/ClangBuiltLinux/linux/issues/805
Reported-by: Dmitry Golovin <dima@golovin.in>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Ilie Halip <ilie.halip@gmail.com>
Reviewed-by: Fangrui Song <maskray@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
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Add SPDX License Identifier to all .gitignore files.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Temporary files used in the VDSO build process linger on even after make
mrproper: vdso-dummy.o.tmp, vdso.so.dbg.tmp.
Delete them once they're no longer needed.
Signed-off-by: Ilie Halip <ilie.halip@gmail.com>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
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This patch fix following perf record error by linking vdso.so with
build id.
perf.data perf.data.old
[ perf record: Woken up 1 times to write data ]
free(): double free detected in tcache 2
Aborted
perf record use filename__read_build_id(util/symbol-minimal.c) to get
build id when libelf is not supported. When vdso.so is linked without
build id, the section size of PT_NOTE will be zero, buf size will
realloc to zero and cause memory corruption.
Signed-off-by: Mao Han <han_mao@c-sky.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
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Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation version 2 this program is distributed
in the hope that it will be useful but without any warranty without
even the implied warranty of merchantability or fitness for a
particular purpose see the gnu general public license for more
details
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 97 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190529141901.025053186@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Add SPDX license identifiers to all Make/Kconfig files which:
- Have no license information of any form
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Towards the goal of removing cc-ldoption, it seems that --hash-style=
was added to binutils 2.17.50.0.2 in 2006. The minimal required version
of binutils for the kernel according to
Documentation/process/changes.rst is 2.20.
Link: https://gcc.gnu.org/ml/gcc/2007-01/msg01141.html
Cc: clang-built-linux@googlegroups.com
Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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We don't yet have an upstream glibc port for riscv, so there is no user
space for the existing ABI, and we can remove the definitions for 32-bit
time_t, off_t and struct resource and system calls based on them,
including the vdso.
Reviewed-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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If you use a 64-bit compiler to build a 32-bit kernel then you'll get an
error when building the vDSO due to a library mismatch. The happens
because the relevant "-march" argument isn't supplied to the GCC run
that generates one of the vDSO intermediate files.
I'm not actually sure what the right thing to do here is as I'm not
particularly familiar with the kernel build system. I poked the
documentation and it appears that KCFLAGS is the correct thing to do
(it's suggested that should be used when building modules), but we set
KBUILD_CFLAGS in arch/riscv/Makefile.
This does at least fix the build error.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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Debian toolcahin defaults to PIE, and I guess that will also be the case
of most distributions. This causes the following build failure:
AS arch/riscv/kernel/vdso/getcpu.o
AS arch/riscv/kernel/vdso/flush_icache.o
VDSOLD arch/riscv/kernel/vdso/vdso.so.dbg
OBJCOPY arch/riscv/kernel/vdso/vdso.so
AS arch/riscv/kernel/vdso/vdso.o
VDSOLD arch/riscv/kernel/vdso/vdso-dummy.o
LD arch/riscv/kernel/vdso/vdso-syms.o
riscv64-linux-gnu-ld: attempted static link of dynamic object `arch/riscv/kernel/vdso/vdso-dummy.o'
make[2]: *** [arch/riscv/kernel/vdso/Makefile:43: arch/riscv/kernel/vdso/vdso-syms.o] Error 1
make[1]: *** [scripts/Makefile.build:575: arch/riscv/kernel/vdso] Error 2
make: *** [Makefile:1018: arch/riscv/kernel] Error 2
While the root Makefile correctly passes "-fno-PIE" to build individual
object files, the RISC-V kernel also builds vdso-dummy.o as an
executable, which is therefore linked as PIE. Fix that by updating this
specific link rule to also include "-no-pie".
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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We were hoping to avoid making this visible to userspace, but it looks
like we're going to have to because QEMU's user-mode emulation doesn't
want to emulate a vDSO. Having vDSO-only system calls was a bit
unothodox anyway, so I think in this case it's OK to just make the
actual system call number public.
This patch simply moves the definition of __NR_riscv_flush_icache
availiable to userspace, which results in the deletion of the now empty
vdso-syscalls.h.
Changes since v1:
* I've moved the definition into uapi/asm/syscalls.h rathen than
uapi/asm/unistd.h. This allows me to keep asm/unistd.h, so we can
keep the syscall table macros sane.
* As a side effect of the above, this no longer disables all system
calls on RISC-V. Whoops!
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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Despite RISC-V having a direct 'fence.i' instruction available to
userspace (which we can't trap!), that's not actually viable when
running on Linux because the kernel might schedule a process on another
hart. There is no way for userspace to handle this without invoking the
kernel (as it doesn't know the thread->hart mappings), so we've defined
a RISC-V specific system call to flush the instruction cache.
This patch adds both a system call and a VDSO entry. If possible, we'd
like to avoid having the system call be considered part of the
user-facing ABI and instead restrict that to the VDSO entry -- both just
in general to avoid having additional user-visible ABI to maintain, and
because we'd prefer that users just call the VDSO entry because there
might be a better way to do this in the future (ie, one that doesn't
require entering the kernel).
Signed-off-by: Andrew Waterman <andrew@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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For now these are just placeholders that execute the syscall. We will
later optimize them to avoid kernel crossings, but we'd like to have the
VDSO entries from the first released kernel version to make the ABI
simpler.
Signed-off-by: Andrew Waterman <andrew@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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These were left over from an earlier version of the port.
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
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This patch contains code that is in some way visible to the user:
including via system calls, the VDSO, module loading and signal
handling. It also contains some generic code that is ABI visible.
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
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