From: "Maciej W. Rozycki" <macro@imgtec.com>
To: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: <linux-mips@linux-mips.org>, <linux-kernel@vger.kernel.org>,
Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [PATCH] MIPS: Differentiate between 32 and 64 bit ELF header
Date: Mon, 1 Feb 2016 00:52:28 +0000 [thread overview]
Message-ID: <alpine.DEB.2.00.1602010038230.5958@tp.orcam.me.uk> (raw)
In-Reply-To: <1454074137-16334-1-git-send-email-daniel.wagner@bmw-carit.de>
On Fri, 29 Jan 2016, Daniel Wagner wrote:
> Depending on the configuration either the 32 or 64 bit version of
> elf_check_arch() is defined. parse_crash_elf32_headers() does
> some basic verification of the ELF header via elf_check_arch().
> parse_crash_elf64_headers() does it via vmcore_elf64_check_arch()
> which expands to the same elf_check_check().
>
> In file included from include/linux/elf.h:4:0,
> from fs/proc/vmcore.c:13:
> fs/proc/vmcore.c: In function 'parse_crash_elf64_headers':
> >> arch/mips/include/asm/elf.h:228:23: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types]
> struct elfhdr *__h = (hdr); \
> ^
> include/linux/crash_dump.h:41:37: note: in expansion of macro 'elf_check_arch'
> #define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x))
> ^
> fs/proc/vmcore.c:1015:4: note: in expansion of macro 'vmcore_elf64_check_arch'
> !vmcore_elf64_check_arch(&ehdr) ||
> ^
>
> Since the MIPS ELF header for 32 bit and 64 bit differ we need
> to check accordingly.
I fail to see how it can work as it stands given that `elf_check_arch' is
called from the same source file both on a pointer to `Elf32_Ehdr' and one
to `Elf64_Ehdr'. However the MIPS implementations of `elf_check_arch'
only use an auxiliary variable to avoid multiple evaluation of a macro
argument and therefore instead I recommend the use of the usual approach
taken in such a situation within a statement expression, that is to
declare the variable with `typeof' rather than an explicit type. As an
upside this will minimise code disruption as well.
For consistency I suggest making the same change to the `elf_check_arch'
definitions in arch/mips/kernel/binfmt_elf*.c as well.
Maciej
next prev parent reply other threads:[~2016-02-01 0:56 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-28 14:44 [PATCH tip v6 0/5] Simple wait queue support Daniel Wagner
2016-01-28 14:44 ` [PATCH tip v6 1/5] wait.[ch]: Introduce the simple waitqueue (swait) implementation Daniel Wagner
2016-01-28 14:44 ` [PATCH tip v6 2/5] kbuild: Add option to turn incompatible pointer check into error Daniel Wagner
2016-01-29 12:17 ` Daniel Wagner
2016-01-29 18:55 ` Paul Gortmaker
2016-02-01 6:49 ` Daniel Wagner
2016-02-05 8:16 ` Daniel Wagner
2016-02-07 4:39 ` Paul Gortmaker
2016-02-17 13:04 ` Daniel Wagner
2016-01-28 14:44 ` [PATCH tip v6 3/5] KVM: use simple waitqueue for vcpu->wq Daniel Wagner
2016-01-29 12:18 ` Daniel Wagner
2016-01-28 14:44 ` [PATCH tip v6 4/5] rcu: Do not call rcu_nocb_gp_cleanup() while holding rnp->lock Daniel Wagner
2016-01-28 14:44 ` [PATCH tip v6 5/5] rcu: use simple wait queues where possible in rcutree Daniel Wagner
2016-01-29 13:23 ` [PATCH] video: Use bool instead int pointer for get_opt_bool() argument Daniel Wagner
2016-01-29 13:28 ` [PATCH] MIPS: Differentiate between 32 and 64 bit ELF header Daniel Wagner
2016-02-01 0:52 ` Maciej W. Rozycki [this message]
2016-02-01 16:07 ` Daniel Wagner
2016-02-06 17:16 ` Maciej W. Rozycki
2016-02-08 15:44 ` [PATCH v3 0/3] " Daniel Wagner
2016-02-08 15:44 ` [PATCH v3 1/3] mips: Use arch specific auxvec.h instead of generic-asm version Daniel Wagner
2016-02-08 17:19 ` Maciej W. Rozycki
2016-02-09 7:01 ` Daniel Wagner
2016-02-09 11:46 ` Maciej W. Rozycki
2016-02-09 12:37 ` Daniel Wagner
2016-02-09 14:51 ` Maciej W. Rozycki
2016-02-10 8:51 ` Daniel Wagner
2016-02-08 15:44 ` [PATCH v3 2/3] crash_dump: Add vmcore_elf32_check_arch Daniel Wagner
2016-02-08 17:05 ` Maciej W. Rozycki
2016-02-08 15:44 ` [PATCH v3 3/3] mips: Differentiate between 32 and 64 bit ELF header Daniel Wagner
2016-02-08 16:22 ` kbuild test robot
2016-02-09 8:03 ` Daniel Wagner
2016-02-09 12:32 ` Maciej W. Rozycki
2016-02-09 12:38 ` Daniel Wagner
2016-02-09 19:44 ` Maciej W. Rozycki
2016-02-10 6:28 ` Daniel Wagner
2016-02-10 9:21 ` [PATCH v4 0/2] " Daniel Wagner
2016-02-10 9:21 ` [PATCH v4 1/2] crash_dump: Add vmcore_elf32_check_arch Daniel Wagner
2016-02-10 9:21 ` [PATCH v4 2/2] mips: Differentiate between 32 and 64 bit ELF header Daniel Wagner
2016-02-11 10:49 ` Ralf Baechle
2016-02-11 12:04 ` Maciej W. Rozycki
2016-02-11 12:14 ` Daniel Wagner
2016-02-11 14:58 ` Maciej W. Rozycki
2016-02-11 15:30 ` Ralf Baechle
2016-02-08 16:58 ` [PATCH v3 3/3] " Maciej W. Rozycki
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