| Message ID | 20190121170404.142966-3-james.morse@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fix some KVM/HYP interactions with kprobes | expand |
On Mon, 21 Jan 2019 17:04:02 +0000 James Morse <james.morse@arm.com> 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@kernel.org> Thank you, > Signed-off-by: James Morse <james.morse@arm.com> > 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 >
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; }
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. Signed-off-by: James Morse <james.morse@arm.com> 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(-)