linux-kernel - Re: [PATCH] vmcore: replace Elf64_Ehdr/Elf32_Ehdr with elfhdr

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Message-ID: <20150918054907.GA6349@dhcp-128-25.nay.redhat.com>
Date:	Fri, 18 Sep 2015 13:49:07 +0800
From:	Minfei Huang <mhuang@...hat.com>
To:	yjin <yanjiang.jin@...driver.com>
Cc:	kexec@...ts.infradead.org, akpm@...ux-foundation.org,
	jinyanjiang@...il.com, linux-kernel@...r.kernel.org,
	chaowang@...hat.com
Subject: Re: [PATCH] vmcore: replace Elf64_Ehdr/Elf32_Ehdr with elfhdr

On 09/17/15 at 05:32pm, yjin wrote:
> 
> On 2015年09月16日 18:39, Minfei Huang wrote:
> >On 09/16/15 at 10:58am, yanjiang.jin@...driver.com wrote:
> >>From: Yanjiang Jin <yanjiang.jin@...driver.com>
> >>
> >>Function parse_crash_elf_headers() reads e_ident[EI_CLASS] then decides to
> >>call parse_crash_elf64_headers() or parse_crash_elf32_headers().
> >>But this happens in run time, not compile time. So compiler will report
> >>the below warning:
> >>
> >>In file included from include/linux/elf.h:4:0,
> >>                  from fs/proc/vmcore.c:13:
> >>fs/proc/vmcore.c: In function 'parse_crash_elf32_headers':
> >>arch/mips/include/asm/elf.h:258:23: warning: initializatio
> >>n from incompatible pointer type
> >>   struct elfhdr *__h = (hdr);     \
> >>                        ^
> >How about converting the hdr to type elfhdr in above sentence, like
> >following.
> >
> >struct elfhdr *__h = (struct elfhdr *)(hdr);
> 
> Yes, this is a replacement, and it seems more safe because it just
> affects MIPS arch.
> But I also can't see any obvious impact if modifying common vmcore.c:-)

Without the Maro define, elfhdr is not the struct in the code source.
Thus there is some unconvenience for people to read the code, if there
is another thought to fix this issue. 

Please do the converting in the Maro, and repost the new version.

Thanks
Minfei

> Anyway, if you stick to your opinion, I can send a V2 patch to
> update mips' elf.h rather than vmcore.c.
> 
> Thanks!
> Yanjiang
> >
> >Thanks
> >Minfei
> >
> >>fs/proc/vmcore.c:1071:4: note: in expansion of macro 'elf_
> >>check_arch'
> >>    !elf_check_arch(&ehdr) ||
> >>     ^
> >>
> >>Signed-off-by: Yanjiang Jin <yanjiang.jin@...driver.com>
> >>---
> >>  fs/proc/vmcore.c | 4 ++--
> >>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>
> >>diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> >>index 4e61388..576bb26 100644
> >>--- a/fs/proc/vmcore.c
> >>+++ b/fs/proc/vmcore.c
> >>@@ -999,7 +999,7 @@ static void free_elfcorebuf(void)
> >>  static int __init parse_crash_elf64_headers(void)
> >>  {
> >>  	int rc=0;
> >>-	Elf64_Ehdr ehdr;
> >>+	struct elfhdr ehdr;
> >>  	u64 addr;
> >>  	addr = elfcorehdr_addr;
> >>@@ -1055,7 +1055,7 @@ fail:
> >>  static int __init parse_crash_elf32_headers(void)
> >>  {
> >>  	int rc=0;
> >>-	Elf32_Ehdr ehdr;
> >>+	struct elfhdr ehdr;
> >>  	u64 addr;
> >>  	addr = elfcorehdr_addr;
> 
> 
> _______________________________________________
> kexec mailing list
> kexec@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
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