aboutsummaryrefslogtreecommitdiff
path: root/arch
diff options
context:
space:
mode:
authorRussell King <rmk+kernel@arm.linux.org.uk>2011-07-05 09:01:13 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-07-19 11:44:06 +0100
commit4348810a241a330d3d143d62d7c988ec8b2e6629 (patch)
tree057e8799eb71e35702f39dc276bceb5d93567000 /arch
parenteb96c925152fc289311e5d7e956b919e9b60ab53 (diff)
downloadlinux-linaro-stable-4348810a241a330d3d143d62d7c988ec8b2e6629.tar.gz
ARM: btc: avoid invalidating the branch target cache on kernel TLB maintanence
Kernel space needs very little in the way of BTC maintanence as most mappings which are created and destroyed are non-executable, and so could never enter the instruction stream. The case which does warrant BTC maintanence is when a module is loaded. This creates a new executable mapping, but at that point the pages have not been initialized with code and data, so at that point they contain unpredictable information. Invalidating the BTC at this stage serves little useful purpose. Before we execute module code, we call flush_icache_range(), which deals with the BTC maintanence requirements. This ensures that we have a BTC maintanence operation before we execute code via the newly created mapping. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm/include/asm/tlbflush.h58
-rw-r--r--arch/arm/mm/tlb-fa.S4
-rw-r--r--arch/arm/mm/tlb-v6.S4
-rw-r--r--arch/arm/mm/tlb-v7.S6
4 files changed, 12 insertions, 60 deletions
diff --git a/arch/arm/include/asm/tlbflush.h b/arch/arm/include/asm/tlbflush.h
index d2005de383b8..8077145698ff 100644
--- a/arch/arm/include/asm/tlbflush.h
+++ b/arch/arm/include/asm/tlbflush.h
@@ -34,16 +34,12 @@
#define TLB_V6_D_ASID (1 << 17)
#define TLB_V6_I_ASID (1 << 18)
-#define TLB_BTB (1 << 28)
-
/* Unified Inner Shareable TLB operations (ARMv7 MP extensions) */
#define TLB_V7_UIS_PAGE (1 << 19)
#define TLB_V7_UIS_FULL (1 << 20)
#define TLB_V7_UIS_ASID (1 << 21)
-/* Inner Shareable BTB operation (ARMv7 MP extensions) */
-#define TLB_V7_IS_BTB (1 << 22)
-
+#define TLB_BARRIER (1 << 28)
#define TLB_L2CLEAN_FR (1 << 29) /* Feroceon */
#define TLB_DCLEAN (1 << 30)
#define TLB_WB (1 << 31)
@@ -58,7 +54,7 @@
* v4wb - ARMv4 with write buffer without I TLB flush entry instruction
* v4wbi - ARMv4 with write buffer with I TLB flush entry instruction
* fr - Feroceon (v4wbi with non-outer-cacheable page table walks)
- * fa - Faraday (v4 with write buffer with UTLB and branch target buffer (BTB))
+ * fa - Faraday (v4 with write buffer with UTLB)
* v6wbi - ARMv6 with write buffer with I TLB flush entry instruction
* v7wbi - identical to v6wbi
*/
@@ -99,7 +95,7 @@
# define v4_always_flags (-1UL)
#endif
-#define fa_tlb_flags (TLB_WB | TLB_BTB | TLB_DCLEAN | \
+#define fa_tlb_flags (TLB_WB | TLB_DCLEAN | TLB_BARRIER | \
TLB_V4_U_FULL | TLB_V4_U_PAGE)
#ifdef CONFIG_CPU_TLB_FA
@@ -166,7 +162,7 @@
# define v4wb_always_flags (-1UL)
#endif
-#define v6wbi_tlb_flags (TLB_WB | TLB_DCLEAN | TLB_BTB | \
+#define v6wbi_tlb_flags (TLB_WB | TLB_DCLEAN | TLB_BARRIER | \
TLB_V6_I_FULL | TLB_V6_D_FULL | \
TLB_V6_I_PAGE | TLB_V6_D_PAGE | \
TLB_V6_I_ASID | TLB_V6_D_ASID)
@@ -184,9 +180,9 @@
# define v6wbi_always_flags (-1UL)
#endif
-#define v7wbi_tlb_flags_smp (TLB_WB | TLB_DCLEAN | TLB_V7_IS_BTB | \
+#define v7wbi_tlb_flags_smp (TLB_WB | TLB_DCLEAN | TLB_BARRIER | \
TLB_V7_UIS_FULL | TLB_V7_UIS_PAGE | TLB_V7_UIS_ASID)
-#define v7wbi_tlb_flags_up (TLB_WB | TLB_DCLEAN | TLB_BTB | \
+#define v7wbi_tlb_flags_up (TLB_WB | TLB_DCLEAN | TLB_BARRIER | \
TLB_V6_U_FULL | TLB_V6_U_PAGE | TLB_V6_U_ASID)
#ifdef CONFIG_CPU_TLB_V7
@@ -341,15 +337,7 @@ static inline void local_flush_tlb_all(void)
if (tlb_flag(TLB_V7_UIS_FULL))
asm("mcr p15, 0, %0, c8, c3, 0" : : "r" (zero) : "cc");
- if (tlb_flag(TLB_BTB)) {
- /* flush the branch target cache */
- asm("mcr p15, 0, %0, c7, c5, 6" : : "r" (zero) : "cc");
- dsb();
- isb();
- }
- if (tlb_flag(TLB_V7_IS_BTB)) {
- /* flush the branch target cache */
- asm("mcr p15, 0, %0, c7, c1, 6" : : "r" (zero) : "cc");
+ if (tlb_flag(TLB_BARRIER)) {
dsb();
isb();
}
@@ -389,17 +377,8 @@ static inline void local_flush_tlb_mm(struct mm_struct *mm)
asm("mcr p15, 0, %0, c8, c3, 2" : : "r" (asid) : "cc");
#endif
- if (tlb_flag(TLB_BTB)) {
- /* flush the branch target cache */
- asm("mcr p15, 0, %0, c7, c5, 6" : : "r" (zero) : "cc");
- dsb();
- }
- if (tlb_flag(TLB_V7_IS_BTB)) {
- /* flush the branch target cache */
- asm("mcr p15, 0, %0, c7, c1, 6" : : "r" (zero) : "cc");
+ if (tlb_flag(TLB_BARRIER))
dsb();
- isb();
- }
}
static inline void
@@ -439,17 +418,8 @@ local_flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
asm("mcr p15, 0, %0, c8, c3, 1" : : "r" (uaddr) : "cc");
#endif
- if (tlb_flag(TLB_BTB)) {
- /* flush the branch target cache */
- asm("mcr p15, 0, %0, c7, c5, 6" : : "r" (zero) : "cc");
- dsb();
- }
- if (tlb_flag(TLB_V7_IS_BTB)) {
- /* flush the branch target cache */
- asm("mcr p15, 0, %0, c7, c1, 6" : : "r" (zero) : "cc");
+ if (tlb_flag(TLB_BARRIER))
dsb();
- isb();
- }
}
static inline void local_flush_tlb_kernel_page(unsigned long kaddr)
@@ -482,15 +452,7 @@ static inline void local_flush_tlb_kernel_page(unsigned long kaddr)
if (tlb_flag(TLB_V7_UIS_PAGE))
asm("mcr p15, 0, %0, c8, c3, 1" : : "r" (kaddr) : "cc");
- if (tlb_flag(TLB_BTB)) {
- /* flush the branch target cache */
- asm("mcr p15, 0, %0, c7, c5, 6" : : "r" (zero) : "cc");
- dsb();
- isb();
- }
- if (tlb_flag(TLB_V7_IS_BTB)) {
- /* flush the branch target cache */
- asm("mcr p15, 0, %0, c7, c1, 6" : : "r" (zero) : "cc");
+ if (tlb_flag(TLB_BARRIER)) {
dsb();
isb();
}
diff --git a/arch/arm/mm/tlb-fa.S b/arch/arm/mm/tlb-fa.S
index 9694f1f6f485..d887a31faaae 100644
--- a/arch/arm/mm/tlb-fa.S
+++ b/arch/arm/mm/tlb-fa.S
@@ -46,7 +46,6 @@ ENTRY(fa_flush_user_tlb_range)
add r0, r0, #PAGE_SZ
cmp r0, r1
blo 1b
- mcr p15, 0, r3, c7, c5, 6 @ invalidate BTB
mcr p15, 0, r3, c7, c10, 4 @ data write barrier
mov pc, lr
@@ -60,9 +59,8 @@ ENTRY(fa_flush_kern_tlb_range)
add r0, r0, #PAGE_SZ
cmp r0, r1
blo 1b
- mcr p15, 0, r3, c7, c5, 6 @ invalidate BTB
mcr p15, 0, r3, c7, c10, 4 @ data write barrier
- mcr p15, 0, r3, c7, c5, 4 @ prefetch flush
+ mcr p15, 0, r3, c7, c5, 4 @ prefetch flush (isb)
mov pc, lr
__INITDATA
diff --git a/arch/arm/mm/tlb-v6.S b/arch/arm/mm/tlb-v6.S
index 73d7d89b04c4..ffe06a69a6e5 100644
--- a/arch/arm/mm/tlb-v6.S
+++ b/arch/arm/mm/tlb-v6.S
@@ -54,7 +54,6 @@ ENTRY(v6wbi_flush_user_tlb_range)
add r0, r0, #PAGE_SZ
cmp r0, r1
blo 1b
- mcr p15, 0, ip, c7, c5, 6 @ flush BTAC/BTB
mcr p15, 0, ip, c7, c10, 4 @ data synchronization barrier
mov pc, lr
@@ -83,9 +82,8 @@ ENTRY(v6wbi_flush_kern_tlb_range)
add r0, r0, #PAGE_SZ
cmp r0, r1
blo 1b
- mcr p15, 0, r2, c7, c5, 6 @ flush BTAC/BTB
mcr p15, 0, r2, c7, c10, 4 @ data synchronization barrier
- mcr p15, 0, r2, c7, c5, 4 @ prefetch flush
+ mcr p15, 0, r2, c7, c5, 4 @ prefetch flush (isb)
mov pc, lr
__INIT
diff --git a/arch/arm/mm/tlb-v7.S b/arch/arm/mm/tlb-v7.S
index 53cd5b454673..86bb71664508 100644
--- a/arch/arm/mm/tlb-v7.S
+++ b/arch/arm/mm/tlb-v7.S
@@ -48,9 +48,6 @@ ENTRY(v7wbi_flush_user_tlb_range)
add r0, r0, #PAGE_SZ
cmp r0, r1
blo 1b
- mov ip, #0
- ALT_SMP(mcr p15, 0, ip, c7, c1, 6) @ flush BTAC/BTB Inner Shareable
- ALT_UP(mcr p15, 0, ip, c7, c5, 6) @ flush BTAC/BTB
dsb
mov pc, lr
ENDPROC(v7wbi_flush_user_tlb_range)
@@ -75,9 +72,6 @@ ENTRY(v7wbi_flush_kern_tlb_range)
add r0, r0, #PAGE_SZ
cmp r0, r1
blo 1b
- mov r2, #0
- ALT_SMP(mcr p15, 0, r2, c7, c1, 6) @ flush BTAC/BTB Inner Shareable
- ALT_UP(mcr p15, 0, r2, c7, c5, 6) @ flush BTAC/BTB
dsb
isb
mov pc, lr