Hi Naresh,
On Tue, Jan 25, 2022 at 07:18:16PM +0530, Naresh Kamboju wrote:
> Hi Greg,
>
> Regression found on
> stable-rc 5.4 queue riscv tinyconfig build failed.
>
> Not sure which patch is causing build failures.
> We will bisect and get back to you.
These should not be recent failures on 5.4, they should have always been
there.
> make --silent --keep-going --jobs=8
> O=/home/tuxbuild/.cache/tuxmake/builds/current LLVM_IAS=1 ARCH=riscv
> CROSS_COMPILE=riscv64-linux-gnu- HOSTCC=clang CC=clang
>
> In file included from /builds/linux/kernel/dma/mapping.c:8:
> In file included from /builds/linux/include/linux/memblock.h:13:
> In file included from /builds/linux/include/linux/mm.h:10:
> In file included from /builds/linux/include/linux/gfp.h:6:
> In file included from /builds/linux/include/linux/mmzone.h:8:
> In file included from /builds/linux/include/linux/spinlock.h:51:
> In file included from /builds/linux/include/linux/preempt.h:78:
> In file included from ./arch/riscv/include/generated/asm/preempt.h:1:
> In file included from /builds/linux/include/asm-generic/preempt.h:5:
> In file included from /builds/linux/include/linux/thread_info.h:22:
> /builds/linux/arch/riscv/include/asm/current.h:30:9: warning: variable
> 'tp' is uninitialized when used here [-Wuninitialized]
> return tp;
> ^~
> /builds/linux/arch/riscv/include/asm/current.h:29:33: note: initialize
> the variable 'tp' to silence this warning
> register struct task_struct *tp __asm__("tp");
> ^
> = NULL
Resolved by commit 52e7c52d2ded ("RISC-V: Stop relying on GCC's register
allocator's hueristics").
It had two follow up fixes:
af2bdf828f79 ("RISC-V: stacktrace: Declare sp_in_global outside ifdef")
8356c379cfba ("RISC-V: gp_in_global needs register keyword")
> clang: warning: argument unused during compilation: '-no-pie'
> [-Wunused-command-line-argument]
Resolved by commit 7f3d349065d0 ("riscv: Use $(LD) instead of $(CC) to
link vDSO"). I don't think that will backport clean but it is not an
error so I would not worry about it.
> In file included from /builds/linux/arch/riscv/kernel/cpu.c:7:
> In file included from /builds/linux/include/linux/seq_file.h:8:
> In file included from /builds/linux/include/linux/mutex.h:14:
> /builds/linux/arch/riscv/include/asm/current.h:30:9: warning: variable
> 'tp' is uninitialized when used here [-Wuninitialized]
> return tp;
> ^~
> /builds/linux/arch/riscv/include/asm/current.h:29:33: note: initialize
> the variable 'tp' to silence this warning
> register struct task_struct *tp __asm__("tp");
> ^
> = NULL
> 1 warning generated.
> 1 warning generated.
> 1 warning generated.
> 1 warning generated.
> <instantiation>:1:1: error: unrecognized instruction mnemonic
> LOCAL _restore_kernel_tpsp
> ^
> /builds/linux/arch/riscv/kernel/entry.S:163:2: note: while in macro
> instantiation
> SAVE_ALL
> ^
> <instantiation>:2:2: error: unrecognized instruction mnemonic
> LOCAL _save_context
> ^
Should be resolved with commits fdff9911f266 ("RISC-V: Inline the
assembly register save/restore macros") and abc71bf0a703 ("RISC-V: Stop
using LOCAL for the uaccess fixups").
There might be other issues lurking, I would not say we had decent
RISC-V build support with LLVM until maybe 5.10 or so (that is the
version that we start testing RISC-V at in our CI).
Cheers,
Nathan
