arm64: entry.S: Add ventry overflow sanity checks

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>

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index ca978d7d98eb49e5d1ecdbf769b36311ed38586e..0414b0494dd37e0bfc9c7aaf5e04c420dec3b646 100644 (file)
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -74,6 +74,7 @@
 
        .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
@@ -89,6 +90,7 @@ alternative_else_nop_endif
 
        sub     sp, sp, #S_FRAME_SIZE
        b       el\()\el\()_\label
+.org .Lventry_start\@ + 128    // Did we overflow the ventry slot?
        .endm
 
        .macro tramp_alias, dst, sym
@@ -935,6 +937,7 @@ __ni_sys_trace:
        add     x30, x30, #(1b - tramp_vectors)
        isb
        ret
+.org 1b + 128  // Did we overflow the ventry slot?
        .endm
 
        .macro tramp_exit, regsize = 64