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Merge branch 'sparc64-context-wrap-fixes' 

Pavel Tatashin says:

====================
sparc64: context wrap fixes

This patch series contains fixes for context wrap: when we are out of
context ids, and need to get a new version.

It fixes memory corruption issues which happen when more than number of
context ids (currently set to 8K) number of processes are started
simultaneously, and processes can get a wrong context.

sparc64: new context wrap:
- contains explanation of new wrap method, and also explanation of races
  that it solves
sparc64: reset mm cpumask after wrap
- explains issue of not reseting cpu mask on a wrap
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2017-06-06 13:45:48 -07:00
parent f322980b74 0197e41ce7
commit b3aefc2fbd
8 changed files with 64 additions and 96 deletions
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2
arch/sparc/include/asm/mmu_64.h
View File

@ -52,7 +52,7 @@
#define CTX_NR_MASK TAG_CONTEXT_BITS
#define CTX_HW_MASK (CTX_NR_MASK | CTX_PGSZ_MASK)
#define CTX_FIRST_VERSION ((_AC(1,UL) << CTX_VERSION_SHIFT) + _AC(1,UL))
#define CTX_FIRST_VERSION BIT(CTX_VERSION_SHIFT)
#define CTX_VALID(__ctx) \
(!(((__ctx.sparc64_ctx_val) ^ tlb_context_cache) & CTX_VERSION_MASK))
#define CTX_HWBITS(__ctx) ((__ctx.sparc64_ctx_val) & CTX_HW_MASK)

32
arch/sparc/include/asm/mmu_context_64.h
View File

@ -19,13 +19,8 @@ extern spinlock_t ctx_alloc_lock;
extern unsigned long tlb_context_cache;
extern unsigned long mmu_context_bmap[];
DECLARE_PER_CPU(struct mm_struct *, per_cpu_secondary_mm);
void get_new_mmu_context(struct mm_struct *mm);
#ifdef CONFIG_SMP
void smp_new_mmu_context_version(void);
#else
#define smp_new_mmu_context_version() do { } while (0)
#endif
int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
void destroy_context(struct mm_struct *mm);
@ -76,8 +71,9 @@ void __flush_tlb_mm(unsigned long, unsigned long);
static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, struct task_struct *tsk)
{
unsigned long ctx_valid, flags;
int cpu;
int cpu = smp_processor_id();
per_cpu(per_cpu_secondary_mm, cpu) = mm;
if (unlikely(mm == &init_mm))
return;
@ -123,7 +119,6 @@ static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, str
* for the first time, we must flush that context out of the
* local TLB.
*/
cpu = smp_processor_id();
if (!ctx_valid || !cpumask_test_cpu(cpu, mm_cpumask(mm))) {
cpumask_set_cpu(cpu, mm_cpumask(mm));
__flush_tlb_mm(CTX_HWBITS(mm->context),
@ -133,26 +128,7 @@ static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, str
}
#define deactivate_mm(tsk,mm) do { } while (0)
/* Activate a new MM instance for the current task. */
static inline void activate_mm(struct mm_struct *active_mm, struct mm_struct *mm)
{
unsigned long flags;
int cpu;
spin_lock_irqsave(&mm->context.lock, flags);
if (!CTX_VALID(mm->context))
get_new_mmu_context(mm);
cpu = smp_processor_id();
if (!cpumask_test_cpu(cpu, mm_cpumask(mm)))
cpumask_set_cpu(cpu, mm_cpumask(mm));
load_secondary_context(mm);
__flush_tlb_mm(CTX_HWBITS(mm->context), SECONDARY_CONTEXT);
tsb_context_switch(mm);
spin_unlock_irqrestore(&mm->context.lock, flags);
}
#define activate_mm(active_mm, mm) switch_mm(active_mm, mm, NULL)
#endif /* !(__ASSEMBLY__) */
#endif /* !(__SPARC64_MMU_CONTEXT_H) */

1
arch/sparc/include/asm/pil.h
View File

@ -20,7 +20,6 @@
#define PIL_SMP_CALL_FUNC 1
#define PIL_SMP_RECEIVE_SIGNAL 2
#define PIL_SMP_CAPTURE 3
#define PIL_SMP_CTX_NEW_VERSION 4
#define PIL_DEVICE_IRQ 5
#define PIL_SMP_CALL_FUNC_SNGL 6
#define PIL_DEFERRED_PCR_WORK 7

1
arch/sparc/kernel/kernel.h
View File

@ -37,7 +37,6 @@ void handle_stdfmna(struct pt_regs *regs, unsigned long sfar, unsigned long sfsr
/* smp_64.c */
void __irq_entry smp_call_function_client(int irq, struct pt_regs *regs);
void __irq_entry smp_call_function_single_client(int irq, struct pt_regs *regs);
void __irq_entry smp_new_mmu_context_version_client(int irq, struct pt_regs *regs);
void __irq_entry smp_penguin_jailcell(int irq, struct pt_regs *regs);
void __irq_entry smp_receive_signal_client(int irq, struct pt_regs *regs);

31
arch/sparc/kernel/smp_64.c
View File

@ -964,37 +964,6 @@ void flush_dcache_page_all(struct mm_struct *mm, struct page *page)
preempt_enable();
}
void __irq_entry smp_new_mmu_context_version_client(int irq, struct pt_regs *regs)
{
struct mm_struct *mm;
unsigned long flags;
clear_softint(1 << irq);
/* See if we need to allocate a new TLB context because
* the version of the one we are using is now out of date.
*/
mm = current->active_mm;
if (unlikely(!mm || (mm == &init_mm)))
return;
spin_lock_irqsave(&mm->context.lock, flags);
if (unlikely(!CTX_VALID(mm->context)))
get_new_mmu_context(mm);
spin_unlock_irqrestore(&mm->context.lock, flags);
load_secondary_context(mm);
__flush_tlb_mm(CTX_HWBITS(mm->context),
SECONDARY_CONTEXT);
}
void smp_new_mmu_context_version(void)
{
smp_cross_call(&xcall_new_mmu_context_version, 0, 0, 0);
}
#ifdef CONFIG_KGDB
void kgdb_roundup_cpus(unsigned long flags)
{

2
arch/sparc/kernel/ttable_64.S
View File

@ -50,7 +50,7 @@ tl0_resv03e: BTRAP(0x3e) BTRAP(0x3f) BTRAP(0x40)
tl0_irq1: TRAP_IRQ(smp_call_function_client, 1)
tl0_irq2: TRAP_IRQ(smp_receive_signal_client, 2)
tl0_irq3: TRAP_IRQ(smp_penguin_jailcell, 3)
tl0_irq4: TRAP_IRQ(smp_new_mmu_context_version_client, 4)
tl0_irq4: BTRAP(0x44)
#else
tl0_irq1: BTRAP(0x41)
tl0_irq2: BTRAP(0x42)

86
arch/sparc/mm/init_64.c
View File

@ -707,10 +707,58 @@ EXPORT_SYMBOL(__flush_dcache_range);
/* get_new_mmu_context() uses "cache + 1". */
DEFINE_SPINLOCK(ctx_alloc_lock);
unsigned long tlb_context_cache = CTX_FIRST_VERSION - 1;
unsigned long tlb_context_cache = CTX_FIRST_VERSION;
#define MAX_CTX_NR (1UL << CTX_NR_BITS)
#define CTX_BMAP_SLOTS BITS_TO_LONGS(MAX_CTX_NR)
DECLARE_BITMAP(mmu_context_bmap, MAX_CTX_NR);
DEFINE_PER_CPU(struct mm_struct *, per_cpu_secondary_mm) = {0};
static void mmu_context_wrap(void)
{
unsigned long old_ver = tlb_context_cache & CTX_VERSION_MASK;
unsigned long new_ver, new_ctx, old_ctx;
struct mm_struct *mm;
int cpu;
bitmap_zero(mmu_context_bmap, 1 << CTX_NR_BITS);
/* Reserve kernel context */
set_bit(0, mmu_context_bmap);
new_ver = (tlb_context_cache & CTX_VERSION_MASK) + CTX_FIRST_VERSION;
if (unlikely(new_ver == 0))
new_ver = CTX_FIRST_VERSION;
tlb_context_cache = new_ver;
/*
* Make sure that any new mm that are added into per_cpu_secondary_mm,
* are going to go through get_new_mmu_context() path.
*/
mb();
/*
* Updated versions to current on those CPUs that had valid secondary
* contexts
*/
for_each_online_cpu(cpu) {
/*
* If a new mm is stored after we took this mm from the array,
* it will go into get_new_mmu_context() path, because we
* already bumped the version in tlb_context_cache.
*/
mm = per_cpu(per_cpu_secondary_mm, cpu);
if (unlikely(!mm || mm == &init_mm))
continue;
old_ctx = mm->context.sparc64_ctx_val;
if (likely((old_ctx & CTX_VERSION_MASK) == old_ver)) {
new_ctx = (old_ctx & ~CTX_VERSION_MASK) | new_ver;
set_bit(new_ctx & CTX_NR_MASK, mmu_context_bmap);
mm->context.sparc64_ctx_val = new_ctx;
}
}
}
/* Caller does TLB context flushing on local CPU if necessary.
* The caller also ensures that CTX_VALID(mm->context) is false.
@ -726,48 +774,30 @@ void get_new_mmu_context(struct mm_struct *mm)
{
unsigned long ctx, new_ctx;
unsigned long orig_pgsz_bits;
int new_version;
spin_lock(&ctx_alloc_lock);
retry:
/* wrap might have happened, test again if our context became valid */
if (unlikely(CTX_VALID(mm->context)))
goto out;
orig_pgsz_bits = (mm->context.sparc64_ctx_val & CTX_PGSZ_MASK);
ctx = (tlb_context_cache + 1) & CTX_NR_MASK;
new_ctx = find_next_zero_bit(mmu_context_bmap, 1 << CTX_NR_BITS, ctx);
new_version = 0;
if (new_ctx >= (1 << CTX_NR_BITS)) {
new_ctx = find_next_zero_bit(mmu_context_bmap, ctx, 1);
if (new_ctx >= ctx) {
int i;
new_ctx = (tlb_context_cache & CTX_VERSION_MASK) +
CTX_FIRST_VERSION;
if (new_ctx == 1)
new_ctx = CTX_FIRST_VERSION;
/* Don't call memset, for 16 entries that's just
* plain silly...
*/
mmu_context_bmap[0] = 3;
mmu_context_bmap[1] = 0;
mmu_context_bmap[2] = 0;
mmu_context_bmap[3] = 0;
for (i = 4; i < CTX_BMAP_SLOTS; i += 4) {
mmu_context_bmap[i + 0] = 0;
mmu_context_bmap[i + 1] = 0;
mmu_context_bmap[i + 2] = 0;
mmu_context_bmap[i + 3] = 0;
}
new_version = 1;
goto out;
mmu_context_wrap();
goto retry;
}
}
if (mm->context.sparc64_ctx_val)
cpumask_clear(mm_cpumask(mm));
mmu_context_bmap[new_ctx>>6] |= (1UL << (new_ctx & 63));
new_ctx |= (tlb_context_cache & CTX_VERSION_MASK);
out:
tlb_context_cache = new_ctx;
mm->context.sparc64_ctx_val = new_ctx | orig_pgsz_bits;
out:
spin_unlock(&ctx_alloc_lock);
if (unlikely(new_version))
smp_new_mmu_context_version();
}
static int numa_enabled = 1;

5
arch/sparc/mm/ultra.S
View File

@ -971,11 +971,6 @@ xcall_capture:
wr %g0, (1 << PIL_SMP_CAPTURE), %set_softint
retry
.globl xcall_new_mmu_context_version
xcall_new_mmu_context_version:
wr %g0, (1 << PIL_SMP_CTX_NEW_VERSION), %set_softint
retry
#ifdef CONFIG_KGDB
.globl xcall_kgdb_capture
xcall_kgdb_capture: