kernel.git/arch/riscv/kernel/vdso, branch linux-4.19.y

RISC-V: vdso: Do not add missing symbols to version section in linker script

2022-12-08T10:18:29Z

[ Upstream commit fcae44fd36d052e956e69a64642fc03820968d78 ] Recently, ld.lld moved from '--undefined-version' to '--no-undefined-version' as the default, which breaks the compat vDSO build: ld.lld: error: version script assignment of 'LINUX_4.15' to symbol '__vdso_gettimeofday' failed: symbol not defined ld.lld: error: version script assignment of 'LINUX_4.15' to symbol '__vdso_clock_gettime' failed: symbol not defined ld.lld: error: version script assignment of 'LINUX_4.15' to symbol '__vdso_clock_getres' failed: symbol not defined These symbols are not present in the compat vDSO or the regular vDSO for 32-bit but they are unconditionally included in the version section of the linker script, which is prohibited with '--no-undefined-version'. Fix this issue by only including the symbols that are actually exported in the version section of the linker script. Link: https://github.com/ClangBuiltLinux/linux/issues/1756 Signed-off-by: Nathan Chancellor Tested-by: Conor Dooley Link: https://lore.kernel.org/r/20221108171324.3377226-1-nathan@kernel.org/ Signed-off-by: Palmer Dabbelt Signed-off-by: Sasha Levin

riscv: fix vdso build with lld

2020-05-20T06:18:39Z

[ Upstream commit 3c1918c8f54166598195d938564072664a8275b1 ] 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 Reviewed-by: Nick Desaulniers Signed-off-by: Ilie Halip Reviewed-by: Fangrui Song Signed-off-by: Palmer Dabbelt Signed-off-by: Sasha Levin

riscv: delete temporary files

2020-02-05T14:43:48Z

[ Upstream commit 95f4d9cced96afa9c69b3da8e79e96102c84fc60 ] 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 Signed-off-by: Paul Walmsley Signed-off-by: Sasha Levin

RISC-V: Use KBUILD_CFLAGS instead of KCFLAGS when building the vDSO

2018-08-13T15:31:28Z

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 Signed-off-by: Palmer Dabbelt

RISC-V: build vdso-dummy.o with -no-pie

2018-04-24T17:54:46Z

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 Signed-off-by: Palmer Dabbelt

RISC-V: Make __NR_riscv_flush_icache visible to userspace

2018-01-07T23:14:37Z

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

RISC-V: Allow userspace to flush the instruction cache

2017-11-30T20:58:29Z

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 Signed-off-by: Palmer Dabbelt

RISC-V: Add VDSO entries for clock_get/gettimeofday/getcpu

2017-11-27T15:51:39Z

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 Signed-off-by: Palmer Dabbelt

RISC-V: Remove __vdso_cmpxchg{32,64} symbol versions

2017-11-27T15:51:39Z

These were left over from an earlier version of the port. Signed-off-by: Palmer Dabbelt

RISC-V: User-facing API

2017-09-26T22:26:48Z

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