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Andrii Nakryiko d7a252708d libbpf: Improve handling of failed CO-RE relocations
Previously, if libbpf failed to resolve CO-RE relocation for some
instructions, it would either return error immediately, or, if
.relaxed_core_relocs option was set, would replace relocatable offset/imm part
of an instruction with a bogus value (-1). Neither approach is good, because
there are many possible scenarios where relocation is expected to fail (e.g.,
when some field knowingly can be missing on specific kernel versions). On the
other hand, replacing offset with invalid one can hide programmer errors, if
this relocation failue wasn't anticipated.

This patch deprecates .relaxed_core_relocs option and changes the approach to
always replacing instruction, for which relocation failed, with invalid BPF
helper call instruction. For cases where this is expected, BPF program should
already ensure that that instruction is unreachable, in which case this
invalid instruction is going to be silently ignored. But if instruction wasn't
guarded, BPF program will be rejected at verification step with verifier log
pointing precisely to the place in assembly where the problem is.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20200124053837.2434679-1-andriin@fb.com
2020-01-24 22:16:26 +01:00
arch Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-01-23 08:10:16 +01:00
block block: fix an integer overflow in logical block size 2020-01-15 21:43:09 -07:00
certs
crypto tpmdd fixes for Linux v5.5-rc3 2019-12-18 17:17:36 -08:00
Documentation Merge ra.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2020-01-19 22:10:04 +01:00
drivers net: convert suitable drivers to use phy_do_ioctl_running 2020-01-23 10:49:30 +01:00
fs io_uring-5.5-2020-01-16 2020-01-17 11:25:45 -08:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-01-23 08:10:16 +01:00
init Merge ra.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2020-01-19 22:10:04 +01:00
ipc treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kernel bpf, devmap: Pass lockdep expression to RCU lists 2020-01-23 23:01:16 +01:00
lib lib/vdso: Make __cvdso_clock_getres() static 2020-01-10 19:29:01 +01:00
LICENSES
mm mm: memcg/slab: call flush_memcg_workqueue() only if memcg workqueue is valid 2020-01-13 18:19:02 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-01-23 08:10:16 +01:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-01-23 08:10:16 +01:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2020-01-23 08:10:16 +01:00
security net: bridge: vlan: add rtm definitions and dump support 2020-01-15 13:48:17 +01:00
sound sound fixes for 5.5-rc7 2020-01-17 08:38:35 -08:00
tools libbpf: Improve handling of failed CO-RE relocations 2020-01-24 22:16:26 +01:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-04 00:00:48 +09:00
virt PPC KVM fix for 5.5 2019-12-22 13:18:15 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore
.mailmap MAINTAINERS: update my email address 2020-01-11 14:33:39 -08:00
COPYING
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Kbuild
Kconfig
MAINTAINERS Merge ra.kernel.org:/pub/scm/linux/kernel/git/netdev/net 2020-01-19 22:10:04 +01:00
Makefile Linux 5.5-rc6 2020-01-12 16:55:08 -08:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.