Commit f2b3d856 authored Jan 24, 2019 by James Morse Committed by Will Deacon Feb 01, 2019

arm64: kprobe: Always blacklist the KVM world-switch code



On systems with VHE the kernel and KVM's world-switch code run at the
same exception level. Code that is only used on a VHE system does not
need to be annotated as __hyp_text as it can reside anywhere in the
 kernel text.

__hyp_text was also used to prevent kprobes from patching breakpoint
instructions into this region, as this code runs at a different
exception level. While this is no longer true with VHE, KVM still
switches VBAR_EL1, meaning a kprobe's breakpoint executed in the
world-switch code will cause a hyp-panic.

Move the __hyp_text check in the kprobes blacklist so it applies on
VHE systems too, to cover the common code and guest enter/exit
assembly.

Fixes: 888b3c87 ("arm64: Treat all entry code as non-kprobe-able")
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

parent 8ea23593

arch/arm64/kernel/probes/kprobes.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -478,13 +478,13 @@ bool arch_within_kprobe_blacklist(unsigned long addr)
		addr < (unsigned long)__entry_text_end) \|\|
		(addr >= (unsigned long)__idmap_text_start &&
		addr < (unsigned long)__idmap_text_end) \|\|
		(addr >= (unsigned long)__hyp_text_start &&
		addr < (unsigned long)__hyp_text_end) \|\|
		!!search_exception_tables(addr))
		return true;

		if (!is_kernel_in_hyp_mode()) {
		if ((addr >= (unsigned long)__hyp_text_start &&
		addr < (unsigned long)__hyp_text_end) \|\|
		(addr >= (unsigned long)__hyp_idmap_text_start &&
		if ((addr >= (unsigned long)__hyp_idmap_text_start &&
		addr < (unsigned long)__hyp_idmap_text_end))
		return true;
		}