From 7a79d423decaf8a0501343781e2e2480c1470823 Mon Sep 17 00:00:00 2001 From: James Morse Date: Wed, 20 Apr 2022 11:53:32 +0000 Subject: [PATCH] arm64: entry: Make the trampoline cleanup optional stable inclusion from stable-v4.19.236 commit 87eccd56c52fcdd6c55b048d789da5c9c2e51ed3 category: bugfix bugzilla: 186460, https://gitee.com/src-openeuler/kernel/issues/I53MHA CVE: CVE-2022-23960 -------------------------------- commit d739da1694a0eaef0358a42b76904b611539b77b upstream. Subsequent patches will add additional sets of vectors that use the same tricks as the kpti vectors to reach the full-fat vectors. The full-fat vectors contain some cleanup for kpti that is patched in by alternatives when kpti is in use. Once there are additional vectors, the cleanup will be needed in more cases. But on big/little systems, the cleanup would be harmful if no trampoline vector were in use. Instead of forcing CPUs that don't need a trampoline vector to use one, make the trampoline cleanup optional. Entry at the top of the vectors will skip the cleanup. The trampoline vectors can then skip the first instruction, triggering the cleanup to run. Reviewed-by: Russell King (Oracle) Reviewed-by: Catalin Marinas Signed-off-by: James Morse Signed-off-by: Greg Kroah-Hartman Signed-off-by: Chen Jiahao Reviewed-by: Hanjun Guo Reviewed-by: Liao Chang Signed-off-by: Yongqiang Liu --- arch/arm64/kernel/entry.S | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 33a1cbe98e36..ad5432e73538 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -72,16 +72,20 @@ .align 7 .Lventry_start\@: #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 -alternative_if ARM64_UNMAP_KERNEL_AT_EL0 .if \el == 0 + /* + * This must be the first instruction of the EL0 vector entries. It is + * skipped by the trampoline vectors, to trigger the cleanup. + */ + b .Lskip_tramp_vectors_cleanup\@ .if \regsize == 64 mrs x30, tpidrro_el0 msr tpidrro_el0, xzr .else mov x30, xzr .endif +.Lskip_tramp_vectors_cleanup\@: .endif -alternative_else_nop_endif #endif sub sp, sp, #S_FRAME_SIZE @@ -1083,7 +1087,7 @@ alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003 #endif prfm plil1strm, [x30, #(1b - tramp_vectors)] msr vbar_el1, x30 - add x30, x30, #(1b - tramp_vectors) + add x30, x30, #(1b - tramp_vectors + 4) isb ret .org 1b + 128 // Did we overflow the ventry slot? -- GitLab