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    Subject[PATCH 4.9 57/96] arm64: kprobe: Always blacklist the KVM world-switch code
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    [ 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 30bcae0aef2a..d2b1b624ddc3 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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