[PATCH v2 06/11] arm64: Move post_ttbr_update_workaround to C code

Will Deacon
2018-01-05T13:12:36Z

From: Marc Zyngier <marc.zyngier@arm.com>

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>
---
arch/arm64/include/asm/assembler.h | 13 -------------
arch/arm64/kernel/entry.S | 2 +-
arch/arm64/mm/context.c | 9 +++++++++
arch/arm64/mm/proc.S | 3 +--
4 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h
index c45bc94f15d0..cee60ce0da52 100644
--- a/arch/arm64/include/asm/assembler.h
+++ b/arch/arm64/include/asm/assembler.h
@@ -476,17 +476,4 @@ alternative_endif
mrs \rd, sp_el0
.endm

-/*
- * Errata workaround post TTBRx_EL1 update.
- */
- .macro post_ttbr_update_workaround
-#ifdef CONFIG_CAVIUM_ERRATUM_27456
-alternative_if ARM64_WORKAROUND_CAVIUM_27456
- ic iallu
- dsb nsh
- isb
-alternative_else_nop_endif
-#endif
- .endm
-
#endif /* __ASM_ASSEMBLER_H */
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 71092ee09b6b..62500d371b06 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -277,7 +277,7 @@ alternative_else_nop_endif
* Cavium erratum 27456 (broadcast TLBI instructions may cause I-cache
* corruption).
*/
- post_ttbr_update_workaround
+ bl post_ttbr_update_workaround
.endif
1:
.if \el != 0
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c
index 1cb3bc92ae5c..5f7097d0cd12 100644
--- a/arch/arm64/mm/context.c
+++ b/arch/arm64/mm/context.c
@@ -239,6 +239,15 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu)
cpu_switch_mm(mm->pgd, mm);
}

+/* Errata workaround post TTBRx_EL1 update. */
+asmlinkage void post_ttbr_update_workaround(void)
+{
+ asm(ALTERNATIVE("nop; nop; nop",
+ "ic iallu; dsb nsh; isb",
+ ARM64_WORKAROUND_CAVIUM_27456,
+ CONFIG_CAVIUM_ERRATUM_27456));
+}
+
static int asids_init(void)
{
asid_bits = get_cpu_asid_bits();
diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
index 3146dc96f05b..6affb68a9a14 100644
--- a/arch/arm64/mm/proc.S
+++ b/arch/arm64/mm/proc.S
@@ -145,8 +145,7 @@ ENTRY(cpu_do_switch_mm)
isb
msr ttbr0_el1, x0 // now update TTBR0
isb
- post_ttbr_update_workaround
- ret
+ b post_ttbr_update_workaround // Back to C code...
ENDPROC(cpu_do_switch_mm)

.pushsection ".idmap.text", "ax"
--
2.1.4