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Josh Poimboeuf 6f5ec2993b objtool: Detect RIP-relative switch table references
Typically a switch table can be found by detecting a .rodata access
followed an indirect jump:

    1969:	4a 8b 0c e5 00 00 00 	mov    0x0(,%r12,8),%rcx
    1970:	00
			196d: R_X86_64_32S	.rodata+0x438
    1971:	e9 00 00 00 00       	jmpq   1976 <dispc_runtime_suspend+0xb6a>
			1972: R_X86_64_PC32	__x86_indirect_thunk_rcx-0x4

Randy Dunlap reported a case (seen with GCC 4.8) where the .rodata
access uses RIP-relative addressing:

    19bd:	48 8b 3d 00 00 00 00 	mov    0x0(%rip),%rdi        # 19c4 <dispc_runtime_suspend+0xbb8>
			19c0: R_X86_64_PC32	.rodata+0x45c
    19c4:	e9 00 00 00 00       	jmpq   19c9 <dispc_runtime_suspend+0xbbd>
			19c5: R_X86_64_PC32	__x86_indirect_thunk_rdi-0x4

In this case the relocation addend needs to be adjusted accordingly in
order to find the location of the switch table.

The fix is for case 3 (as described in the comments), but also make the
existing case 1 & 2 checks more precise by only adjusting the addend for
R_X86_64_PC32 relocations.

This fixes the following warnings:

  drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_suspend()+0xbb8: sibling call from callable instruction with modified stack frame
  drivers/video/fbdev/omap2/omapfb/dss/dispc.o: warning: objtool: dispc_runtime_resume()+0xcc5: sibling call from callable instruction with modified stack frame

Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/b6098294fd67afb69af8c47c9883d7a68bf0f8ea.1526305958.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-05-15 07:30:59 +02:00
arch x86/cpufeature: Guard asm_volatile_goto usage for BPF compilation 2018-05-13 21:49:14 +02:00
block
certs
crypto
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-05-11 14:14:46 -07:00
drivers Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux 2018-05-12 10:58:57 -07:00
firmware
fs some small SMB3 fixes for 4.17-rc5, some for stable 2018-05-12 18:49:53 -07:00
include Merge branch 'akpm' (patches from Andrew) 2018-05-11 18:04:12 -07:00
init init: fix false positives in W+X checking 2018-05-11 17:28:45 -07:00
ipc
kernel Merge branch 'akpm' (patches from Andrew) 2018-05-11 18:04:12 -07:00
lib lib/find_bit_benchmark.c: avoid soft lockup in test_find_first_bit() 2018-05-11 17:28:45 -07:00
LICENSES
mm Merge branch 'akpm' (patches from Andrew) 2018-05-11 18:04:12 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-05-11 14:14:46 -07:00
samples x86/cpufeature: Guard asm_volatile_goto usage for BPF compilation 2018-05-13 21:49:14 +02:00
scripts scripts/faddr2line: fix error when addr2line output contains discriminator 2018-05-11 17:28:45 -07:00
security
sound ALSA: pcm: Check PCM state at xfern compat ioctl 2018-05-02 08:54:54 +02:00
tools objtool: Detect RIP-relative switch table references 2018-05-15 07:30:59 +02:00
usr
virt KVM/arm fixes for 4.17, take #2 2018-05-05 23:05:31 +02:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge branch 'akpm' (patches from Andrew) 2018-05-11 18:04:12 -07:00
Makefile Linux 4.17-rc4 2018-05-06 16:57:38 -10:00
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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.