FROMLIST: arm64: Move post_ttbr_update_workaround to C code
We will soon need to invoke a CPU-specific function pointer after changing
page tables, so move post_ttbr_update_workaround out into C code to make
this possible.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
commit 400a169447ad2268b023637a118fba27246bcc19)
Change-Id: Ic21e59001470a2e88db7291eb5f6393f8a64a7dd
[ghackmann@google.com: 3.18 doesn't support CPUs that need the Cavium
errata, so for now post_ttbr_update_workaround() is an empty stub that
will be used in a later patch series.]
Signed-off-by: Greg Hackmann <ghackmann@google.com>
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index c2c3c0d9..ab284aa 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -213,6 +213,16 @@
.endif
__uaccess_ttbr0_enable x0, x1
+
+ .if \el == 0
+ /*
+ * Enable errata workarounds only if returning to user. The only
+ * workaround currently required for TTBR0_EL1 changes are for the
+ * Cavium erratum 27456 (broadcast TLBI instructions may cause I-cache
+ * corruption).
+ */
+ bl post_ttbr_update_workaround
+ .endif
1:
.if \el != 0
and x22, x22, #~PSR_PAN_BIT // ARMv8.0 CPUs do not understand this bit
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index 10d68e4..cc3664b 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -199,6 +199,11 @@
cpu_switch_mm(mm->pgd, mm);
}
+/* Errata workaround post TTBRx_EL1 update. */
+asmlinkage void post_ttbr_update_workaround(void)
+{
+}
+
static int asids_init(void)
{
int fld = cpuid_feature_extract_field(read_cpuid(SYS_ID_AA64MMFR0_EL1), 4);
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 31c0d8c..f24e67a 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -134,7 +134,7 @@
isb
msr ttbr0_el1, x0 // now update TTBR0
isb
- ret
+ b post_ttbr_update_workaround // Back to C code...
ENDPROC(cpu_do_switch_mm)
.section ".text.init", #alloc, #execinstr
