linux-kernel - Re: [PATCH] riscv: relocate R_RISCV_CALL_PLT in kexec

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Date:   Tue, 21 Mar 2023 16:03:49 +0100
From:   Torsten Duwe <duwe@....de>
To:     Palmer Dabbelt <palmer@...belt.com>
Cc:     Li Zhengyu <lizhengyu3@...wei.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Li Huafei <lihuafei1@...wei.com>,
        "Liao Chang" <liaochang1@...wei.com>,
        <linux-riscv@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <liubao918@...wei.com>
Subject: Re: [PATCH] riscv: relocate R_RISCV_CALL_PLT in kexec_file

On Mon, 13 Mar 2023 11:13:17 +0800
Li Zhengyu <lizhengyu3@...wei.com> wrote:

> On Fri, 10 Mar 2023 19:27:03 +0100, Torsten Duwe <duwe@....de> wrote:
> > Depending on the toolchain (here: gcc-12, binutils-2.40) the
> > relocation entries for function calls are no longer R_RISCV_CALL, but
> > R_RISCV_CALL_PLT. When trying kexec_load_file on such kernels, it will
> > fail with
> >
> >   kexec_image: Unknown rela relocation: 19
> >   kexec_image: Error loading purgatory ret=-8
> >
> > The binary code at the call site remains the same, so tell
> > arch_kexec_apply_relocations_add() to handle _PLT alike.
> 
> R_RISCV_CALL has already been deprecated, and replaced by R_RISCV_CALL_PLT.
> 
> See Enum 18-19 in Table 3. Relocation types from 
> https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc 
> .
> 
> It was deprecated in ("Deprecated R_RISCV_CALL, prefer 
> R_RISCV_CALL_PLT") 
> https://github.com/riscv-non-isa/riscv-elf-psabi-doc/commit/a0dced85018d7a0ec17023c9389cbd70b1dbc1b0
> 
> >
> > fixes: 838b3e28488f702 ("Load purgatory in kexec_file")
> > Signed-off-by: Torsten Duwe <duwe@...e.de>
> > Cc: stable@...r.kernel.org
> >
> > ---
> > --- a/arch/riscv/kernel/elf_kexec.c
> > +++ b/arch/riscv/kernel/elf_kexec.c
> > @@ -425,6 +425,7 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
> >   		 * sym, instead of searching the whole relsec.
> >   		 */
> >   		case R_RISCV_PCREL_HI20:
> > +		case R_RISCV_CALL_PLT:
> >   		case R_RISCV_CALL:
> >   			*(u64 *)loc = CLEAN_IMM(UITYPE, *(u64 *)loc) |
> >   				 ENCODE_UJTYPE_IMM(val - addr);
> >
> > .
> 
> Palmer, please apply these references to the commit message.
> 
> Reviewed-by: Li Zhengyu <lizhengyu3@...wei.com>
> 

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