From: Nathan Chancellor <nathan@kernel.org>
To: WANG Rui <wangrui@loongson.cn>
Cc: Huacai Chen <chenhuacai@kernel.org>,
WANG Xuerui <kernel@xen0n.name>,
Jinyang He <hejinyang@loongson.cn>,
Xi Ruoyao <xry111@xry111.site>,
linux-kernel@vger.kernel.org, loongarch@lists.linux.dev,
linux-kbuild@vger.kernel.org, llvm@lists.linux.dev,
loongson-kernel@lists.loongnix.cn
Subject: Re: [PATCH] LoongArch: Record pc instead of offset in la-abs relocation
Date: Mon, 20 Nov 2023 16:08:17 -0700 [thread overview]
Message-ID: <20231120230817.GA2116806@dev-arch.thelio-3990X> (raw)
In-Reply-To: <20231116130331.241395-1-wangrui@loongson.cn>
Hi Rui,
On Thu, Nov 16, 2023 at 09:03:31PM +0800, WANG Rui wrote:
> To clarify, the previous version functioned flawlessly. However, it's
> worth noting that the LLVM's LoongArch backend currently lacks support
> for cross-section label calculations. With this patch, we enable the use
> of clang to compile relocatable kernels.
>
> Signed-off-by: WANG Rui <wangrui@loongson.cn>
Thanks a lot for the patch! This fixes the CONFIG_RELOCATABLE build for
me as well.
Tested-by: Nathan Chancellor <nathan@kernel.org>
Something I noticed while testing is that a kernel linked with ld.lld
does not boot while one linked with ld.bfd did. I think this might be
the same issue that Xuerui filed on our issue tracker but I figured I
would mention it in case not:
https://github.com/ClangBuiltLinux/linux/issues/1883
Cheers,
Nathan
> ---
> arch/loongarch/include/asm/asmmacro.h | 3 +--
> arch/loongarch/include/asm/setup.h | 2 +-
> arch/loongarch/kernel/relocate.c | 2 +-
> 3 files changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/arch/loongarch/include/asm/asmmacro.h b/arch/loongarch/include/asm/asmmacro.h
> index c9544f358c33..655db7d7a427 100644
> --- a/arch/loongarch/include/asm/asmmacro.h
> +++ b/arch/loongarch/include/asm/asmmacro.h
> @@ -609,8 +609,7 @@
> lu32i.d \reg, 0
> lu52i.d \reg, \reg, 0
> .pushsection ".la_abs", "aw", %progbits
> - 768:
> - .dword 768b-766b
> + .dword 766b
> .dword \sym
> .popsection
> #endif
> diff --git a/arch/loongarch/include/asm/setup.h b/arch/loongarch/include/asm/setup.h
> index a0bc159ce8bd..ee52fb1e9963 100644
> --- a/arch/loongarch/include/asm/setup.h
> +++ b/arch/loongarch/include/asm/setup.h
> @@ -25,7 +25,7 @@ extern void set_merr_handler(unsigned long offset, void *addr, unsigned long len
> #ifdef CONFIG_RELOCATABLE
>
> struct rela_la_abs {
> - long offset;
> + long pc;
> long symvalue;
> };
>
> diff --git a/arch/loongarch/kernel/relocate.c b/arch/loongarch/kernel/relocate.c
> index 6c3eff9af9fb..288b739ca88d 100644
> --- a/arch/loongarch/kernel/relocate.c
> +++ b/arch/loongarch/kernel/relocate.c
> @@ -52,7 +52,7 @@ static inline void __init relocate_absolute(long random_offset)
> for (p = begin; (void *)p < end; p++) {
> long v = p->symvalue;
> uint32_t lu12iw, ori, lu32id, lu52id;
> - union loongarch_instruction *insn = (void *)p - p->offset;
> + union loongarch_instruction *insn = (void *)p->pc;
>
> lu12iw = (v >> 12) & 0xfffff;
> ori = v & 0xfff;
> --
> 2.42.1
>
>
next prev parent reply other threads:[~2023-11-20 23:08 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-16 13:03 WANG Rui
2023-11-20 23:08 ` Nathan Chancellor [this message]
2023-11-21 1:32 ` Huacai Chen
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