x86/unwind/orc: Fix premature unwind stoppage due to IRET frames
commit 81b67439 upstream. The following execution path is possible: fsnotify() [ realign the stack and store previous SP in R10 ] <IRQ> [ only IRET regs saved ] common_interrupt() interrupt_entry() <NMI> [ full pt_regs saved ] ... [ unwind stack ] When the unwinder goes through the NMI and the IRQ on the stack, and then sees fsnotify(), it doesn't have access to the value of R10, because it only has the five IRET registers. So the unwind stops prematurely. However, because the interrupt_entry() code is careful not to clobber R10 before saving the full regs, the unwinder should be able to read R10 from the previously saved full pt_regs associated with the NMI. Handle this case properly. When encountering an IRET regs frame immediately after a full pt_regs frame, use the pt_regs as a backup which can be used to get the C register values. Also, note that a call frame resets the 'prev_regs' value, because a function is free to clobber the registers. For this fix to work, the IRET and full regs frames must be adjacent, with no FUNC frames in between. So replace the FUNC hint in interrupt_entry() with an IRET_REGS hint. Fixes: ee9f8fce ("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/97a408167cc09f1cfa0de31a7b70dd88868d743f.1587808742.git.jpoimboe@redhat.com Signed-off-by:
Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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e356bf88
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