On Fri, Mar 11, 2022 at 09:15:32AM +0100, Greg Kroah-Hartman wrote:
On Fri, Mar 11, 2022 at 12:27:29AM +0100, Pavel Machek wrote:
Hi!
From: James Morse james.morse@arm.com
commit ba2689234be92024e5635d30fe744f4853ad97db upstream.
Some CPUs affected by Spectre-BHB need a sequence of branches, or a firmware call to be run before any indirect branch. This needs to go in the vectors. No CPU needs both.
While this can be patched in, it would run on all CPUs as there is a single set of vectors. If only one part of a big/little combination is affected, the unaffected CPUs have to run the mitigation too.
This adds build error. Same problem is in 5.10.
--- /dev/null +++ b/arch/arm64/include/asm/vectors.h @@ -0,0 +1,34 @@
...
+/*
- Note: the order of this enum corresponds to two arrays in entry.S:
- tramp_vecs and __bp_harden_el1_vectors. By default the canonical
- 'full fat' vectors are used directly.
- */
+enum arm64_bp_harden_el1_vectors { +#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
- /*
* Perform the BHB loop mitigation, before branching to the canonical* vectors.*/- EL1_VECTOR_BHB_LOOP,
- /*
* Make the SMC call for firmware mitigation, before branching to the* canonical vectors.*/- EL1_VECTOR_BHB_FW,
+#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
- /*
* Remap the kernel before branching to the canonical vectors.*/- EL1_VECTOR_KPTI,
++};
Note "++". Following patch fixes this up, but it is still a trap for people trying to bisect.
Ick, ok, will try to fix up, thanks for finding this.
Now fixed up for 5.16.y, 5.15.y, and 5.10.y, thanks.
greg k-h