ARM: proc-v7: avoid errata 430973 workaround for non-Cortex A8 CPUs

Avoid the errata 430973 workaround for non-Cortex A8 CPUs.  Having this
workaround enabled introduces an additional branch target buffer flush
into the context switching path, something we wish to avoid.  To allow
this errata to be enabled in multiplatform kernels while reducing its
impact, rearrange the Cortex-A8 CPU support to avoid impacting on other
Version 7 CPUs.

Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

2 files changed, 36 insertions, 4 deletions

diff --git a/arch/arm/mm/proc-v7-2level.S b/arch/arm/mm/proc-v7-2level.S
index ed448d8a596b..10405b8d31af 100644
--- a/arch/arm/mm/proc-v7-2level.S
+++ b/arch/arm/mm/proc-v7-2level.S
@@ -37,15 +37,18 @@
  *      It is assumed that:
  *      - we are not using split page tables
  */
-ENTRY(cpu_v7_switch_mm)
+ENTRY(cpu_ca8_switch_mm)
 #ifdef CONFIG_MMU
         mov     r2, #0
-        mmid    r1, r1                          @ get mm->context.id
-        ALT_SMP(orr     r0, r0, #TTB_FLAGS_SMP)
-        ALT_UP(orr      r0, r0, #TTB_FLAGS_UP)
 #ifdef CONFIG_ARM_ERRATA_430973
         mcr     p15, 0, r2, c7, c5, 6           @ flush BTAC/BTB
 #endif
+#endif
+ENTRY(cpu_v7_switch_mm)
+#ifdef CONFIG_MMU
+        mmid    r1, r1                          @ get mm->context.id
+        ALT_SMP(orr     r0, r0, #TTB_FLAGS_SMP)
+        ALT_UP(orr      r0, r0, #TTB_FLAGS_UP)
 #ifdef CONFIG_PID_IN_CONTEXTIDR
         mrc     p15, 0, r2, c13, c0, 1          @ read current context ID
         lsr     r2, r2, #8                      @ extract the PID
@@ -61,6 +64,7 @@ ENTRY(cpu_v7_switch_mm)
 #endif
         bx      lr
 ENDPROC(cpu_v7_switch_mm)
+ENDPROC(cpu_ca8_switch_mm)
 
 /*
  *      cpu_v7_set_pte_ext(ptep, pte)
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
index 6bdaa4cc1784..3d1054f11a8a 100644
--- a/arch/arm/mm/proc-v7.S
+++ b/arch/arm/mm/proc-v7.S
@@ -153,6 +153,21 @@ ENDPROC(cpu_v7_do_resume)
 #endif
 
 /*
+ * Cortex-A8
+ */
+        globl_equ       cpu_ca8_proc_init,      cpu_v7_proc_init
+        globl_equ       cpu_ca8_proc_fin,       cpu_v7_proc_fin
+        globl_equ       cpu_ca8_reset,          cpu_v7_reset
+        globl_equ       cpu_ca8_do_idle,        cpu_v7_do_idle
+        globl_equ       cpu_ca8_dcache_clean_area, cpu_v7_dcache_clean_area
+        globl_equ       cpu_ca8_set_pte_ext,    cpu_v7_set_pte_ext
+        globl_equ       cpu_ca8_suspend_size,   cpu_v7_suspend_size
+#ifdef CONFIG_ARM_CPU_SUSPEND
+        globl_equ       cpu_ca8_do_suspend,     cpu_v7_do_suspend
+        globl_equ       cpu_ca8_do_resume,      cpu_v7_do_resume
+#endif
+
+/*
  * Cortex-A9 processor functions
  */
         globl_equ       cpu_ca9mp_proc_init,    cpu_v7_proc_init
@@ -451,7 +466,10 @@ __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
+#ifndef CONFIG_ARM_LPAE
+        define_processor_functions ca8, dabort=v7_early_abort, pabort=v7_pabort, suspend=1
         define_processor_functions ca9mp, dabort=v7_early_abort, pabort=v7_pabort, suspend=1
+#endif
 #ifdef CONFIG_CPU_PJ4B
         define_processor_functions pj4b, dabort=v7_early_abort, pabort=v7_pabort, suspend=1
 #endif
@@ -507,6 +525,16 @@ __v7_ca9mp_proc_info:
         __v7_proc __v7_ca9mp_proc_info, __v7_ca9mp_setup, proc_fns = ca9mp_processor_functions
         .size   __v7_ca9mp_proc_info, . - __v7_ca9mp_proc_info
 
+        /*
+         * ARM Ltd. Cortex A8 processor.
+         */
+        .type   __v7_ca8_proc_info, #object
+__v7_ca8_proc_info:
+        .long   0x410fc080
+        .long   0xff0ffff0
+        __v7_proc __v7_ca8_proc_info, __v7_setup, proc_fns = ca8_processor_functions
+        .size   __v7_ca8_proc_info, . - __v7_ca8_proc_info
+
 #endif  /* CONFIG_ARM_LPAE */
 
         /*