[PATCH v2 4/6] arm: Add icache invalidation on switch_mm for Cortex-A15

[Marc Zyngier]

In order to avoid aliasing attacks against the branch predictor,
Cortex-A15 require to invalidate the BTB when switching
from one user context to another. The only way to do so on this
CPU is to perform an ICIALLU, having set ACTLR[0] to 1 from secure
mode.

Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
---
 arch/arm/mm/proc-v7-2level.S | 10 ++++++++++
 arch/arm/mm/proc-v7-3level.S | 16 ++++++++++++++++
 arch/arm/mm/proc-v7.S        | 18 +++++++++++++++++-
 3 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mm/proc-v7-2level.S b/arch/arm/mm/proc-v7-2level.S
index 0422e58b74e8..7dc9e1c69039 100644
--- a/arch/arm/mm/proc-v7-2level.S
+++ b/arch/arm/mm/proc-v7-2level.S
@@ -40,7 +40,17 @@
  *	Note that we always need to flush BTAC/BTB if IBE is set
  *	even on Cortex-A8 revisions not affected by 430973.
  *	If IBE is not set, the flush BTAC/BTB won't do anything.
+ *
+ *	Cortex-A15 requires ACTLR[0] to be set from secure in order
+ *	for the icache invalidation to also invalidate the BTB.
  */
+ENTRY(cpu_ca15_switch_mm)
+#ifdef CONFIG_MMU
+	mcr	p15, 0, r0, c7, c5, 0			@ ICIALLU
+	isb
+	b	cpu_v7_switch_mm
+#endif
+ENDPROC(cpu_ca15_switch_mm)
 ENTRY(cpu_v7_btbinv_switch_mm)
 #ifdef CONFIG_MMU
 	mov	r2, #0
diff --git a/arch/arm/mm/proc-v7-3level.S b/arch/arm/mm/proc-v7-3level.S
index f6adfe88ead2..0a2245b309e5 100644
--- a/arch/arm/mm/proc-v7-3level.S
+++ b/arch/arm/mm/proc-v7-3level.S
@@ -71,6 +71,22 @@ ENTRY(cpu_v7_switch_mm)
 ENDPROC(cpu_v7_switch_mm)
 ENDPROC(cpu_v7_btbinv_switch_mm)
 
+/*
+ *	Cortex-A15 requires ACTLR[0] to be set from secure in order
+ *	for the icache invalidation to also invalidate the BTB.
+ */
+ENTRY(cpu_ca15_switch_mm)
+#ifdef CONFIG_MMU
+	mcr	p15, 0, r0, c7, c5, 0			@ ICIALLU
+	mmid	r2, r2
+	asid	r2, r2
+	orr	rpgdh, rpgdh, r2, lsl #(48 - 32)	@ upper 32-bits of pgd
+	mcrr	p15, 0, rpgdl, rpgdh, c2		@ set TTB 0
+	isb
+#endif
+	ret	lr
+ENDPROC(cpu_ca15_switch_mm)
+
 #ifdef __ARMEB__
 #define rl r3
 #define rh r2
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 0a14967fd400..9310fd9aa1cf 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -173,6 +173,21 @@ ENDPROC(cpu_v7_do_resume)
 	globl_equ	cpu_v7_btbinv_do_resume,	cpu_v7_do_resume
 #endif
 
+/*
+ * Cortex-A15 that require an icache invalidation on switch_mm
+ */
+	globl_equ	cpu_ca15_proc_init,		cpu_v7_proc_init
+	globl_equ	cpu_ca15_proc_fin,		cpu_v7_proc_fin
+	globl_equ	cpu_ca15_reset,			cpu_v7_reset
+	globl_equ	cpu_ca15_do_idle,		cpu_v7_do_idle
+	globl_equ	cpu_ca15_dcache_clean_area, 	cpu_v7_dcache_clean_area
+	globl_equ	cpu_ca15_set_pte_ext,		cpu_v7_set_pte_ext
+	globl_equ	cpu_ca15_suspend_size,		cpu_v7_suspend_size
+#ifdef CONFIG_ARM_CPU_SUSPEND
+	globl_equ	cpu_ca15_do_suspend,		cpu_v7_do_suspend
+	globl_equ	cpu_ca15_do_resume,		cpu_v7_do_resume
+#endif
+
 /*
  * Cortex-A9 processor functions
  */
@@ -549,6 +564,7 @@ __v7_setup_stack:
 	@ define struct processor (see <asm/proc-fns.h> and proc-macros.S)
 	define_processor_functions v7, dabort=v7_early_abort, pabort=v7_pabort, suspend=1
 	define_processor_functions v7_btbinv, dabort=v7_early_abort, pabort=v7_pabort, suspend=1
+	define_processor_functions ca15, dabort=v7_early_abort, pabort=v7_pabort, suspend=1
 #ifndef CONFIG_ARM_LPAE
 	define_processor_functions ca9mp, dabort=v7_early_abort, pabort=v7_pabort, suspend=1
 #endif
@@ -668,7 +684,7 @@ __v7_ca12mp_proc_info:
 __v7_ca15mp_proc_info:
 	.long	0x410fc0f0
 	.long	0xff0ffff0
-	__v7_proc __v7_ca15mp_proc_info, __v7_ca15mp_setup
+	__v7_proc __v7_ca15mp_proc_info, __v7_ca15mp_setup, proc_fns = ca15_processor_functions
 	.size	__v7_ca15mp_proc_info, . - __v7_ca15mp_proc_info
 
 	/*
-- 
2.14.2