On Mon, 21 Jan 2019 17:04:02 +0000
James Morse <james.morse@xxxxxxx> wrote:
> 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.
>
Looks good to me!
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Thank you,
> Signed-off-by: James Morse <james.morse@xxxxxxx>
> Fixes: 888b3c8720e0 ("arm64: Treat all entry code as non-kprobe-able")
> ---
> 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 2a5b338b2542..f17afb99890c 100644
> --- a/arch/arm64/kernel/probes/kprobes.c
> +++ b/arch/arm64/kernel/probes/kprobes.c
> @@ -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;
> }
> --
> 2.20.1
>
--
Masami Hiramatsu <mhiramat@xxxxxxxxxx>
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