linux-kernel - Re: [PATCH v3 -next 1/6] kexec_file: Fix kexec

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Message-ID: <YompDXEY1MaHElmE@MiWiFi-R3L-srv>
Date:   Sun, 22 May 2022 11:07:57 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Palmer Dabbelt <palmer@...belt.com>
Cc:     lizhengyu3@...wei.com, liaochang1@...wei.com, alex@...ti.fr,
        aou@...s.berkeley.edu, Bjorn Topel <bjorn.topel@...il.com>,
        ebiederm@...ssion.com, guoren@...ux.alibaba.com,
        jszhang@...nel.org, kexec@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        mick@....forth.gr, Paul Walmsley <paul.walmsley@...ive.com>,
        penberg@...nel.org, sunnanyong@...wei.com,
        wangkefeng.wang@...wei.com
Subject: Re: [PATCH v3 -next 1/6] kexec_file: Fix kexec_file.c build error
 for riscv platform

On 05/20/22 at 08:45am, Palmer Dabbelt wrote:
> On Fri, 08 Apr 2022 03:09:09 PDT (-0700), lizhengyu3@...wei.com wrote:
> > From: Liao Chang <liaochang1@...wei.com>
> > 
> > When CONFIG_KEXEC_FILE is set for riscv platform, the compilation of
> > kernel/kexec_file.c generate build error:
> > 
> > kernel/kexec_file.c: In function 'crash_prepare_elf64_headers':
> > ./arch/riscv/include/asm/page.h:110:71: error: request for member 'virt_addr' in something not a structure or union
> >   110 |  ((x) >= PAGE_OFFSET && (!IS_ENABLED(CONFIG_64BIT) || (x) < kernel_map.virt_addr))
> >       |                                                                       ^
> > ./arch/riscv/include/asm/page.h:131:2: note: in expansion of macro 'is_linear_mapping'
> >   131 |  is_linear_mapping(_x) ?       \
> >       |  ^~~~~~~~~~~~~~~~~
> > ./arch/riscv/include/asm/page.h:140:31: note: in expansion of macro '__va_to_pa_nodebug'
> >   140 | #define __phys_addr_symbol(x) __va_to_pa_nodebug(x)
> >       |                               ^~~~~~~~~~~~~~~~~~
> > ./arch/riscv/include/asm/page.h:143:24: note: in expansion of macro '__phys_addr_symbol'
> >   143 | #define __pa_symbol(x) __phys_addr_symbol(RELOC_HIDE((unsigned long)(x), 0))
> >       |                        ^~~~~~~~~~~~~~~~~~
> > kernel/kexec_file.c:1327:36: note: in expansion of macro '__pa_symbol'
> >  1327 |   phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
> > 
> > This occurs is because the "kernel_map" referenced in macro
> > is_linear_mapping()  is suppose to be the one of struct kernel_mapping
> > defined in arch/riscv/mm/init.c, but the 2nd argument of
> > crash_prepare_elf64_header() has same symbol name, in expansion of macro
> > is_linear_mapping in function crash_prepare_elf64_header(), "kernel_map"
> > actually is the local variable.
> > 
> > Signed-off-by: Liao Chang <liaochang1@...wei.com>
> > ---
> >  include/linux/kexec.h | 2 +-
> >  kernel/kexec_file.c   | 4 ++--
> >  2 files changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/include/linux/kexec.h b/include/linux/kexec.h
> > index 58d1b58a971e..ebb1bffbf068 100644
> > --- a/include/linux/kexec.h
> > +++ b/include/linux/kexec.h
> > @@ -227,7 +227,7 @@ struct crash_mem {
> >  extern int crash_exclude_mem_range(struct crash_mem *mem,
> >  				   unsigned long long mstart,
> >  				   unsigned long long mend);
> > -extern int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
> > +extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
> >  				       void **addr, unsigned long *sz);
> >  #endif /* CONFIG_KEXEC_FILE */
> > 
> > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> > index 8347fc158d2b..331a4f0f10f5 100644
> > --- a/kernel/kexec_file.c
> > +++ b/kernel/kexec_file.c
> > @@ -1260,7 +1260,7 @@ int crash_exclude_mem_range(struct crash_mem *mem,
> >  	return 0;
> >  }
> > 
> > -int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
> > +int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
> >  			  void **addr, unsigned long *sz)
> >  {
> >  	Elf64_Ehdr *ehdr;
> > @@ -1324,7 +1324,7 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
> >  	phdr++;
> > 
> >  	/* Prepare PT_LOAD type program header for kernel text region */
> > -	if (kernel_map) {
> > +	if (need_kernel_map) {
> >  		phdr->p_type = PT_LOAD;
> >  		phdr->p_flags = PF_R|PF_W|PF_X;
> >  		phdr->p_vaddr = (unsigned long) _text;
> 
> IMO this is fine: we could rename all the kernel_map stuff in arch/riscv,
> but this is much more self-contained.  It's not been ack'd by anyone else,
> but get_maintainers just suggests the kexec@ list so I'm going to take it
> via the RISC-V tree along with the rest of these.

I ever checked this patch, and thought the renaming of kernel_map in
arch/riscv might be more reasonable, because 'need_kernel_map' is obviously
redundant and looks silly, considering in a generic code. But searching
result of kernel_map under arch/riscv stops me suggesting that.