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    Subject[PATCH 4.19 26/57] arm64: entry.S: Add ventry overflow sanity checks
    Date
    From: James Morse <james.morse@arm.com>

    commit 4330e2c5c04c27bebf89d34e0bc14e6943413067 upstream.

    Subsequent patches add even more code to the ventry slots.
    Ensure kernels that overflow a ventry slot don't get built.

    Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
    Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
    Signed-off-by: James Morse <james.morse@arm.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    arch/arm64/kernel/entry.S | 3 +++
    1 file changed, 3 insertions(+)

    --- a/arch/arm64/kernel/entry.S
    +++ b/arch/arm64/kernel/entry.S
    @@ -70,6 +70,7 @@

    .macro kernel_ventry, el, label, regsize = 64
    .align 7
    +.Lventry_start\@:
    #ifdef CONFIG_UNMAP_KERNEL_AT_EL0
    alternative_if ARM64_UNMAP_KERNEL_AT_EL0
    .if \el == 0
    @@ -127,6 +128,7 @@ alternative_else_nop_endif
    mrs x0, tpidrro_el0
    #endif
    b el\()\el\()_\label
    +.org .Lventry_start\@ + 128 // Did we overflow the ventry slot?
    .endm

    .macro tramp_alias, dst, sym
    @@ -984,6 +986,7 @@ alternative_insn isb, nop, ARM64_WORKARO
    add x30, x30, #(1b - tramp_vectors)
    isb
    ret
    +.org 1b + 128 // Did we overflow the ventry slot?
    .endm

    .macro tramp_exit, regsize = 64

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