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x86/unwind/orc: Prevent unwinding before ORC initialization

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commit 98d0c8ebf7 upstream.

If the unwinder is called before the ORC data has been initialized,
orc_find() returns NULL, and it tries to fall back to using frame
pointers.  This can cause some unexpected warnings during boot.

Move the 'orc_init' check from orc_find() to __unwind_init(), so that it
doesn't even try to unwind from an uninitialized state.

Fixes: ee9f8fce99 ("x86/unwind: Add the ORC unwinder")
Reviewed-by: Miroslav Benes <mbenes@suse.cz>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Dave Jones <dsj@fb.com>
Cc: Jann Horn <jannh@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Link: https://lore.kernel.org/r/069d1499ad606d85532eb32ce39b2441679667d5.1587808742.git.jpoimboe@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Josh Poimboeuf 2020-04-25 05:03:08 -05:00 committed by Greg Kroah-Hartman
parent 73d90e8cd2
commit f5970988a8
1 changed files with 3 additions and 3 deletions
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6
arch/x86/kernel/unwind_orc.c
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@ -90,9 +90,6 @@ static struct orc_entry null_orc_entry = {
static struct orc_entry *orc_find(unsigned long ip)
{
if (!orc_init)
return NULL;
if (ip == 0)
return &null_orc_entry;
@ -508,6 +505,9 @@ EXPORT_SYMBOL_GPL(unwind_next_frame);
void __unwind_start(struct unwind_state *state, struct task_struct *task,
struct pt_regs *regs, unsigned long *first_frame)
{
if (!orc_init)
goto done;
memset(state, 0, sizeof(*state));
state->task = task;