Peter Zijlstra 91517e9518 x86,smap: Fix smap_{save,restore}() alternatives
[ Upstream commit 1ff865e343 ]

As reported by objtool:

  lib/ubsan.o: warning: objtool: .altinstr_replacement+0x0: alternative modifies stack
  lib/ubsan.o: warning: objtool: .altinstr_replacement+0x7: alternative modifies stack

the smap_{save,restore}() alternatives violate (the newly enforced)
rule on stack invariance. That is, due to there only being a single
ORC table it must be valid to any alternative. These alternatives
violate this with the direct result that unwinds will not be correct
when it hits between the PUSH and POP instructions.

Rewrite the functions to only have a conditional jump.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20200429101802.GI13592@hirez.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-06-22 09:30:51 +02:00
2020-06-03 08:21:15 +02:00
2020-06-17 16:40:38 +02:00

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.
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