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Subject[PATCH AUTOSEL 4.9 25/32] arm64: kprobe: Always blacklist the KVM world-switch code
Date
From: James Morse <james.morse@arm.com>

[ Upstream commit f2b3d8566d81deaca31f4e3163def0bea7746e11 ]

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: 888b3c8720e0 ("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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/kernel/probes/kprobes.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index 30bcae0aef2a0..d2b1b624ddc3c 100644
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -546,13 +546,13 @@ 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;
}
--
2.19.1
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