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Check whether the TLB operations need broadcasting on SMP systems
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ARMv7 SMP hardware can handle the TLB maintenance operations
broadcasting in hardware so that the software can avoid the costly IPIs.
This patch adds the necessary checks (the MMFR3 CPUID register) to avoid
the broadcasting if already supported by the hardware.

(this patch is based on the work done by Tony Thompson @ ARM)

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Catalin Marinas committed May 30, 2009
1 parent da055eb commit faa7bc5
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Showing 5 changed files with 105 additions and 36 deletions.
25 changes: 25 additions & 0 deletions arch/arm/include/asm/cputype.h
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,21 @@
#define CPUID_TCM 2
#define CPUID_TLBTYPE 3

#define CPUID_EXT_PFR0 "c1, 0"
#define CPUID_EXT_PFR1 "c1, 1"
#define CPUID_EXT_DFR0 "c1, 2"
#define CPUID_EXT_AFR0 "c1, 3"
#define CPUID_EXT_MMFR0 "c1, 4"
#define CPUID_EXT_MMFR1 "c1, 5"
#define CPUID_EXT_MMFR2 "c1, 6"
#define CPUID_EXT_MMFR3 "c1, 7"
#define CPUID_EXT_ISAR0 "c2, 0"
#define CPUID_EXT_ISAR1 "c2, 1"
#define CPUID_EXT_ISAR2 "c2, 2"
#define CPUID_EXT_ISAR3 "c2, 3"
#define CPUID_EXT_ISAR4 "c2, 4"
#define CPUID_EXT_ISAR5 "c2, 5"

#ifdef CONFIG_CPU_CP15
#define read_cpuid(reg) \
({ \
Expand All @@ -18,9 +33,19 @@
: "cc"); \
__val; \
})
#define read_cpuid_ext(ext_reg) \
({ \
unsigned int __val; \
asm("mrc p15, 0, %0, c0, " ext_reg \
: "=r" (__val) \
: \
: "cc"); \
__val; \
})
#else
extern unsigned int processor_id;
#define read_cpuid(reg) (processor_id)
#define read_cpuid_ext(reg) 0
#endif

/*
Expand Down
26 changes: 24 additions & 2 deletions arch/arm/include/asm/tlbflush.h
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,12 @@
#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)

#define TLB_L2CLEAN_FR (1 << 29) /* Feroceon */
#define TLB_DCLEAN (1 << 30)
#define TLB_WB (1 << 31)
Expand Down Expand Up @@ -176,9 +182,17 @@
# define v6wbi_always_flags (-1UL)
#endif

#ifdef CONFIG_SMP
#define v7wbi_tlb_flags (TLB_WB | TLB_DCLEAN | TLB_BTB | \
TLB_V7_UIS_FULL | TLB_V7_UIS_PAGE | TLB_V7_UIS_ASID)
#else
#define v7wbi_tlb_flags (TLB_WB | TLB_DCLEAN | TLB_BTB | \
TLB_V6_U_FULL | TLB_V6_U_PAGE | TLB_V6_U_ASID)
#endif

#ifdef CONFIG_CPU_TLB_V7
# define v7wbi_possible_flags v6wbi_tlb_flags
# define v7wbi_always_flags v6wbi_tlb_flags
# define v7wbi_possible_flags v7wbi_tlb_flags
# define v7wbi_always_flags v7wbi_tlb_flags
# ifdef _TLB
# define MULTI_TLB 1
# else
Expand Down Expand Up @@ -316,6 +330,8 @@ static inline void local_flush_tlb_all(void)
asm("mcr p15, 0, %0, c8, c6, 0" : : "r" (zero) : "cc");
if (tlb_flag(TLB_V4_I_FULL | TLB_V6_I_FULL))
asm("mcr p15, 0, %0, c8, c5, 0" : : "r" (zero) : "cc");
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 */
Expand Down Expand Up @@ -351,6 +367,8 @@ static inline void local_flush_tlb_mm(struct mm_struct *mm)
asm("mcr p15, 0, %0, c8, c6, 2" : : "r" (asid) : "cc");
if (tlb_flag(TLB_V6_I_ASID))
asm("mcr p15, 0, %0, c8, c5, 2" : : "r" (asid) : "cc");
if (tlb_flag(TLB_V7_UIS_ASID))
asm("mcr p15, 0, %0, c8, c3, 2" : : "r" (asid) : "cc");

if (tlb_flag(TLB_BTB)) {
/* flush the branch target cache */
Expand Down Expand Up @@ -389,6 +407,8 @@ local_flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
asm("mcr p15, 0, %0, c8, c6, 1" : : "r" (uaddr) : "cc");
if (tlb_flag(TLB_V6_I_PAGE))
asm("mcr p15, 0, %0, c8, c5, 1" : : "r" (uaddr) : "cc");
if (tlb_flag(TLB_V7_UIS_PAGE))
asm("mcr p15, 0, %0, c8, c3, 1" : : "r" (uaddr) : "cc");

if (tlb_flag(TLB_BTB)) {
/* flush the branch target cache */
Expand Down Expand Up @@ -424,6 +444,8 @@ static inline void local_flush_tlb_kernel_page(unsigned long kaddr)
asm("mcr p15, 0, %0, c8, c6, 1" : : "r" (kaddr) : "cc");
if (tlb_flag(TLB_V6_I_PAGE))
asm("mcr p15, 0, %0, c8, c5, 1" : : "r" (kaddr) : "cc");
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 */
Expand Down
69 changes: 43 additions & 26 deletions arch/arm/kernel/smp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,7 @@
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>
#include <asm/cputype.h>

/*
* as from 2.5, kernels no longer have an init_tasks structure
Expand Down Expand Up @@ -545,6 +546,12 @@ struct tlb_args {
unsigned long ta_end;
};

/* all SMP configurations have the extended CPUID registers */
static inline int tlb_ops_need_broadcast(void)
{
return ((read_cpuid_ext(CPUID_EXT_MMFR3) >> 12) & 0xf) < 2;
}

static inline void ipi_flush_tlb_all(void *ignored)
{
local_flush_tlb_all();
Expand Down Expand Up @@ -587,51 +594,61 @@ static inline void ipi_flush_tlb_kernel_range(void *arg)

void flush_tlb_all(void)
{
on_each_cpu(ipi_flush_tlb_all, NULL, 1);
if (tlb_ops_need_broadcast())
on_each_cpu(ipi_flush_tlb_all, NULL, 1);
else
local_flush_tlb_all();
}

void flush_tlb_mm(struct mm_struct *mm)
{
on_each_cpu_mask(ipi_flush_tlb_mm, mm, 1, &mm->cpu_vm_mask);
if (tlb_ops_need_broadcast())
on_each_cpu_mask(ipi_flush_tlb_mm, mm, 1, &mm->cpu_vm_mask);
else
local_flush_tlb_mm(mm);
}

void flush_tlb_page(struct vm_area_struct *vma, unsigned long uaddr)
{
struct tlb_args ta;

ta.ta_vma = vma;
ta.ta_start = uaddr;

on_each_cpu_mask(ipi_flush_tlb_page, &ta, 1, &vma->vm_mm->cpu_vm_mask);
if (tlb_ops_need_broadcast()) {
struct tlb_args ta;
ta.ta_vma = vma;
ta.ta_start = uaddr;
on_each_cpu_mask(ipi_flush_tlb_page, &ta, 1, &vma->vm_mm->cpu_vm_mask);
} else
local_flush_tlb_page(vma, uaddr);
}

void flush_tlb_kernel_page(unsigned long kaddr)
{
struct tlb_args ta;

ta.ta_start = kaddr;

on_each_cpu(ipi_flush_tlb_kernel_page, &ta, 1);
if (tlb_ops_need_broadcast()) {
struct tlb_args ta;
ta.ta_start = kaddr;
on_each_cpu(ipi_flush_tlb_kernel_page, &ta, 1);
} else
local_flush_tlb_kernel_page(kaddr);
}

void flush_tlb_range(struct vm_area_struct *vma,
unsigned long start, unsigned long end)
{
struct tlb_args ta;

ta.ta_vma = vma;
ta.ta_start = start;
ta.ta_end = end;

on_each_cpu_mask(ipi_flush_tlb_range, &ta, 1, &vma->vm_mm->cpu_vm_mask);
if (tlb_ops_need_broadcast()) {
struct tlb_args ta;
ta.ta_vma = vma;
ta.ta_start = start;
ta.ta_end = end;
on_each_cpu_mask(ipi_flush_tlb_range, &ta, 1, &vma->vm_mm->cpu_vm_mask);
} else
local_flush_tlb_range(vma, start, end);
}

void flush_tlb_kernel_range(unsigned long start, unsigned long end)
{
struct tlb_args ta;

ta.ta_start = start;
ta.ta_end = end;

on_each_cpu(ipi_flush_tlb_kernel_range, &ta, 1);
if (tlb_ops_need_broadcast()) {
struct tlb_args ta;
ta.ta_start = start;
ta.ta_end = end;
on_each_cpu(ipi_flush_tlb_kernel_range, &ta, 1);
} else
local_flush_tlb_kernel_range(start, end);
}
4 changes: 2 additions & 2 deletions arch/arm/mm/proc-v7.S
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Original file line number Diff line number Diff line change
Expand Up @@ -176,8 +176,8 @@ cpu_v7_name:
*/
__v7_setup:
#ifdef CONFIG_SMP
mrc p15, 0, r0, c1, c0, 1 @ Enable SMP/nAMP mode
orr r0, r0, #(0x1 << 6)
mrc p15, 0, r0, c1, c0, 1 @ Enable SMP/nAMP mode and
orr r0, r0, #(1 << 6) | (1 << 0) @ TLB ops broadcasting
mcr p15, 0, r0, c1, c0, 1
#endif
adr r12, __v7_setup_stack @ the local stack
Expand Down
17 changes: 11 additions & 6 deletions arch/arm/mm/tlb-v7.S
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Original file line number Diff line number Diff line change
Expand Up @@ -42,9 +42,11 @@ ENTRY(v7wbi_flush_user_tlb_range)
mov r1, r1, lsl #PAGE_SHIFT
vma_vm_flags r2, r2 @ get vma->vm_flags
1:
mcr p15, 0, r0, c8, c6, 1 @ TLB invalidate D MVA (was 1)
tst r2, #VM_EXEC @ Executable area ?
mcrne p15, 0, r0, c8, c5, 1 @ TLB invalidate I MVA (was 1)
#ifdef CONFIG_SMP
mcr p15, 0, r0, c8, c3, 1 @ TLB invalidate U MVA (shareable)
#else
mcr p15, 0, r0, c8, c7, 1 @ TLB invalidate U MVA
#endif
add r0, r0, #PAGE_SZ
cmp r0, r1
blo 1b
Expand All @@ -69,8 +71,11 @@ ENTRY(v7wbi_flush_kern_tlb_range)
mov r0, r0, lsl #PAGE_SHIFT
mov r1, r1, lsl #PAGE_SHIFT
1:
mcr p15, 0, r0, c8, c6, 1 @ TLB invalidate D MVA
mcr p15, 0, r0, c8, c5, 1 @ TLB invalidate I MVA
#ifdef CONFIG_SMP
mcr p15, 0, r0, c8, c3, 1 @ TLB invalidate U MVA (shareable)
#else
mcr p15, 0, r0, c8, c7, 1 @ TLB invalidate U MVA
#endif
add r0, r0, #PAGE_SZ
cmp r0, r1
blo 1b
Expand All @@ -87,5 +92,5 @@ ENDPROC(v7wbi_flush_kern_tlb_range)
ENTRY(v7wbi_tlb_fns)
.long v7wbi_flush_user_tlb_range
.long v7wbi_flush_kern_tlb_range
.long v6wbi_tlb_flags
.long v7wbi_tlb_flags
.size v7wbi_tlb_fns, . - v7wbi_tlb_fns

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