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[stable:PATCH,v4.9.309,25/43] arm64: entry.S: Add ventry overflow sanity checks

Message ID 20220406164546.1888528-25-james.morse@arm.com
State New
Headers show
Series None | expand

Commit Message

James Morse April 6, 2022, 4:45 p.m. UTC 
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>
---
 arch/arm64/kernel/entry.S | 3 +++
 1 file changed, 3 insertions(+)
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Patch

diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index ca978d7d98eb..0414b0494dd3 100644
--- 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