releases/4.20.16/arm64-kprobe-always-blacklist-the-kvm-world-switch-c.patch

   1 From b4c415f2450ce739d1a9c9108b74f37d239f8157 Mon Sep 17 00:00:00 2001
   2 From: James Morse <james.morse@arm.com>
   3 Date: Thu, 24 Jan 2019 16:32:55 +0000
   4 Subject: arm64: kprobe: Always blacklist the KVM world-switch code
   5
   6 [ Upstream commit f2b3d8566d81deaca31f4e3163def0bea7746e11 ]
   7
   8 On systems with VHE the kernel and KVM's world-switch code run at the
   9 same exception level. Code that is only used on a VHE system does not
  10 need to be annotated as __hyp_text as it can reside anywhere in the
  11  kernel text.
  12
  13 __hyp_text was also used to prevent kprobes from patching breakpoint
  14 instructions into this region, as this code runs at a different
  15 exception level. While this is no longer true with VHE, KVM still
  16 switches VBAR_EL1, meaning a kprobe's breakpoint executed in the
  17 world-switch code will cause a hyp-panic.
  18
  19 Move the __hyp_text check in the kprobes blacklist so it applies on
  20 VHE systems too, to cover the common code and guest enter/exit
  21 assembly.
  22
  23 Fixes: 888b3c8720e0 ("arm64: Treat all entry code as non-kprobe-able")
  24 Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
  25 Signed-off-by: James Morse <james.morse@arm.com>
  26 Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
  27 Signed-off-by: Will Deacon <will.deacon@arm.com>
  28 Signed-off-by: Sasha Levin <sashal@kernel.org>
  29 ---
  30  arch/arm64/kernel/probes/kprobes.c | 6 +++---
  31  1 file changed, 3 insertions(+), 3 deletions(-)
  32
  33 diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
  34 index 2a5b338b2542..f17afb99890c 100644
  35 --- a/arch/arm64/kernel/probes/kprobes.c
  36 +++ b/arch/arm64/kernel/probes/kprobes.c
  37 @@ -478,13 +478,13 @@ bool arch_within_kprobe_blacklist(unsigned long addr)
  38             addr < (unsigned long)__entry_text_end) ||
  39             (addr >= (unsigned long)__idmap_text_start &&
  40             addr < (unsigned long)__idmap_text_end) ||
  41 +           (addr >= (unsigned long)__hyp_text_start &&
  42 +           addr < (unsigned long)__hyp_text_end) ||
  43             !!search_exception_tables(addr))
  44                 return true;
  45
  46         if (!is_kernel_in_hyp_mode()) {
  47 -               if ((addr >= (unsigned long)__hyp_text_start &&
  48 -                   addr < (unsigned long)__hyp_text_end) ||
  49 -                   (addr >= (unsigned long)__hyp_idmap_text_start &&
  50 +               if ((addr >= (unsigned long)__hyp_idmap_text_start &&
  51                     addr < (unsigned long)__hyp_idmap_text_end))
  52                         return true;
  53         }
  54 --
  55 2.19.1
  56