[PATCH 4.9 25/43] arm64: entry.S: Add ventry overflow sanity checks

Greg Kroah-Hartman
2022-04-06T20:19:18Z

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
@@ -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