Since we've already stepped away from ENABLE is a JMP and DISABLE is a
NOP with the branch_default bits, and are going to make it even worse,
rename it to make it all clearer.
This way we don't mix multiple levels of logic attributes, but have a
plain 'physical' name for what the current instruction patching status
of a jump label is.
This is a first step in removing the naming confusion that has led to
a stream of avoidable bugs such as:
a833581e37 ("x86, perf: Fix static_key bug in load_mm_cr4()")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
[ Beefed up the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull x86 jumplabel changes from Peter Anvin:
"One more x86 tree for this merge window. This tree improves the
handling of jump labels, so that most of the time we don't have to do
a massive initial patching run.
Furthermore, we will error out of the jump label is not what is
expected, eg if it has been corrupted or tampered with"
* 'x86/jumplabel' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/jump-label: Show where and what was wrong on errors
x86/jump-label: Add safety checks to jump label conversions
x86/jump-label: Do not bother updating nops if they are correct
x86/jump-label: Use best default nops for inital jump label calls
When modifying text sections for jump labels, a paranoid check is
performed. If the check fails, the system "bugs". But why it failed
is not shown.
The BUG_ON()s in the jump label update code is replaced with bug_at(ip).
This is a function that will show what pointer failed, and what was
at the location of the failure that made jump label panic.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
As with all modifying of kernel text, we need to be very paranoid.
When converting the jump label locations to and from nops to jumps
a check has been added to make sure what we are replacing is what we
expect, otherwise we bug.
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
On boot up, the jump label init function scans all the jump label locations
and converts them to the best nop for the machine. If the nop is already
the ideal nop, do not bother with changing it.
Cc: Jason Baron <jbaron@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
WARNING: arch/x86/kernel/built-in.o(.text+0x4c71): Section mismatch in
reference from the function arch_jump_label_transform_static() to the
function .init.text:text_poke_early()
The function arch_jump_label_transform_static() references
the function __init text_poke_early().
This is often because arch_jump_label_transform_static lacks a __init
annotation or the annotation of text_poke_early is wrong.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jason Baron <jbaron@redhat.com>
Link: http://lkml.kernel.org/n/tip-9lefe89mrvurrwpqw5h8xm8z@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
