Re: [PATCH v8 22/27] binfmt_elf: Extract .note.gnu.property from an ELF file
From: Dave Martin <Dave.Martin@arm.com>
Date: 2019-08-20 10:02:18
Also in:
linux-arch, linux-doc, linux-mm, lkml
On Tue, Aug 13, 2019 at 01:52:20PM -0700, Yu-cheng Yu wrote:
An ELF file's .note.gnu.property indicates features the executable file
can support. For example, the property GNU_PROPERTY_X86_FEATURE_1_AND
indicates the file supports GNU_PROPERTY_X86_FEATURE_1_IBT and/or
GNU_PROPERTY_X86_FEATURE_1_SHSTK.
With this patch, if an arch needs to setup features from ELF properties,
it needs CONFIG_ARCH_USE_GNU_PROPERTY to be set, and specific
arch_parse_property() and arch_setup_property().
For example, for X86_64:
int arch_setup_property(void *ehdr, void *phdr, struct file *f, bool inter)
{
int r;
uint32_t property;
r = get_gnu_property(ehdr, phdr, f, GNU_PROPERTY_X86_FEATURE_1_AND,
&property);
...
}
This patch is derived from code provided by H.J. Lu [off-list ref].
Signed-off-by: Yu-cheng Yu <redacted>[...] For the hell of it, I tried implementing an alternate version [1] that tries to integrate into the existing ELF loader more directly. This may or may not be a better approach, but tries to solve some issues such as not repeatedly reading and parsing the properties. Cheers ---Dave [1] [RFC PATCH 0/2] ELF: Alternate program property parser https://lore.kernel.org/lkml/1566295063-7387-1-git-send-email-Dave.Martin@arm.com/ (local)