[PATCH 0/4] PREEMPT_RT support for sparc64

[PATCH 0/4] PREEMPT_RT support for sparc64

[Allen Pais]

PREEMPT_RT support for sparc64
All the patches are based on v3.10.24-rt22
commit e88b1c51941d964e77ef7e9099075ae2e8dafd75

Have tested it on UltraSparc T4 (Niagara4). 

Allen Pais (4):
  [V1] sparc64: use generic rwsem spinlocks rt
  [V1] sparc64: support forced irq threading
  [V1] sparc64: convert spinloc_t to raw_spinlock_t in mmu_context_t
  [V1] sparc64: convert ctx_alloc_lock raw_spinlock_t

 arch/sparc/Kconfig                      |    7 +++----
 arch/sparc/include/asm/mmu_64.h         |    2 +-
 arch/sparc/include/asm/mmu_context_64.h |   10 +++++-----
 arch/sparc/kernel/smp_64.c              |    4 ++--
 arch/sparc/mm/init_64.c                 |   14 +++++++-------
 arch/sparc/mm/tsb.c                     |   20 ++++++++++----------
 6 files changed, 28 insertions(+), 29 deletions(-)

-- 
1.7.10.4

[PATCH 1/4] [V1] sparc64: use generic rwsem spinlocks rt

[Allen Pais]

Signed-off-by: Allen Pais <allen.pais@oracle.com>
---
 arch/sparc/Kconfig |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 6787bd3..554995d 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -179,12 +179,10 @@ config NR_CPUS
 source kernel/Kconfig.hz
 
 config RWSEM_GENERIC_SPINLOCK
-	bool
-	default y if SPARC32
+	def_bool PREEMPT_RT_FULL
 
 config RWSEM_XCHGADD_ALGORITHM
-	bool
-	default y if SPARC64
+	def_bool !RWSEM_GENERIC_SPINLOCK && !PREEMPT_RT_FULL
 
 config GENERIC_HWEIGHT
 	bool
-- 
1.7.10.4

[PATCH 2/4] [V1] sparc64: support forced irq threading

[Allen Pais]

Signed-off-by: Allen Pais <allen.pais@oracle.com>
---
 arch/sparc/Kconfig |    1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 554995d..aae5aa9 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -27,6 +27,7 @@ config SPARC
 	select HAVE_DMA_API_DEBUG
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_GENERIC_HARDIRQS
+	select IRQ_FORCED_THREADING
 	select GENERIC_IRQ_SHOW
 	select ARCH_WANT_IPC_PARSE_VERSION
 	select USE_GENERIC_SMP_HELPERS if SMP
-- 
1.7.10.4

[PATCH 3/4] [V1] sparc64: convert spinloc_t to raw_spinlock_t in mmu_context_t

[Allen Pais]

In the attempt of get PREEMPT_RT working on sparc64 using
linux-stable-rt version 3.10.22-rt19+, the kernel crash
with the following trace:

[ 1487.027884] I7: <rt_mutex_setprio+0x3c/0x2c0>
[ 1487.027885] Call Trace:
[ 1487.027887]  [00000000004967dc] rt_mutex_setprio+0x3c/0x2c0
[ 1487.027892]  [00000000004afe20] task_blocks_on_rt_mutex+0x180/0x200
[ 1487.027895]  [0000000000819114] rt_spin_lock_slowlock+0x94/0x300
[ 1487.027897]  [0000000000817ebc] __schedule+0x39c/0x53c
[ 1487.027899]  [00000000008185fc] schedule+0x1c/0xc0
[ 1487.027908]  [000000000048fff4] smpboot_thread_fn+0x154/0x2e0
[ 1487.027913]  [000000000048753c] kthread+0x7c/0xa0
[ 1487.027920]  [00000000004060c4] ret_from_syscall+0x1c/0x2c
[ 1487.027922]  [0000000000000000]           (null)

Thomas debugged this issue and pointed to switch_mm

        spin_lock_irqsave(&mm->context.lock, flags);

context.lock needs to be a raw_spinlock.

Signed-off-by: Allen Pais <allen.pais@oracle.com>
---
 arch/sparc/include/asm/mmu_64.h         |    2 +-
 arch/sparc/include/asm/mmu_context_64.h |    8 ++++----
 arch/sparc/kernel/smp_64.c              |    4 ++--
 arch/sparc/mm/init_64.c                 |    4 ++--
 arch/sparc/mm/tsb.c                     |   16 ++++++++--------
 5 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/arch/sparc/include/asm/mmu_64.h b/arch/sparc/include/asm/mmu_64.h
index 76092c4..e945ddb 100644
--- a/arch/sparc/include/asm/mmu_64.h
+++ b/arch/sparc/include/asm/mmu_64.h
@@ -90,7 +90,7 @@ struct tsb_config {
 #endif
 
 typedef struct {
-	spinlock_t		lock;
+	raw_spinlock_t		lock;
 	unsigned long		sparc64_ctx_val;
 	unsigned long		huge_pte_count;
 	struct page		*pgtable_page;
diff --git a/arch/sparc/include/asm/mmu_context_64.h b/arch/sparc/include/asm/mmu_context_64.h
index 3d528f0..3a85624 100644
--- a/arch/sparc/include/asm/mmu_context_64.h
+++ b/arch/sparc/include/asm/mmu_context_64.h
@@ -77,7 +77,7 @@ static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, str
 	if (unlikely(mm == &init_mm))
 		return;
 
-	spin_lock_irqsave(&mm->context.lock, flags);
+	raw_spin_lock_irqsave(&mm->context.lock, flags);
 	ctx_valid = CTX_VALID(mm->context);
 	if (!ctx_valid)
 		get_new_mmu_context(mm);
@@ -125,7 +125,7 @@ static inline void switch_mm(struct mm_struct *old_mm, struct mm_struct *mm, str
 		__flush_tlb_mm(CTX_HWBITS(mm->context),
 			       SECONDARY_CONTEXT);
 	}
-	spin_unlock_irqrestore(&mm->context.lock, flags);
+	raw_spin_unlock_irqrestore(&mm->context.lock, flags);
 }
 
 #define deactivate_mm(tsk,mm)	do { } while (0)
@@ -136,7 +136,7 @@ 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);
+	raw_spin_lock_irqsave(&mm->context.lock, flags);
 	if (!CTX_VALID(mm->context))
 		get_new_mmu_context(mm);
 	cpu = smp_processor_id();
@@ -146,7 +146,7 @@ static inline void activate_mm(struct mm_struct *active_mm, struct mm_struct *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);
+	raw_spin_unlock_irqrestore(&mm->context.lock, flags);
 }
 
 #endif /* !(__ASSEMBLY__) */
diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 77539ed..f42e1a7 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -975,12 +975,12 @@ void __irq_entry smp_new_mmu_context_version_client(int irq, struct pt_regs *reg
 	if (unlikely(!mm || (mm == &init_mm)))
 		return;
 
-	spin_lock_irqsave(&mm->context.lock, flags);
+	raw_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);
+	raw_spin_unlock_irqrestore(&mm->context.lock, flags);
 
 	load_secondary_context(mm);
 	__flush_tlb_mm(CTX_HWBITS(mm->context),
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index 04fd55a..bd5253d 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -350,7 +350,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *
 
 	mm = vma->vm_mm;
 
-	spin_lock_irqsave(&mm->context.lock, flags);
+	raw_spin_lock_irqsave(&mm->context.lock, flags);
 
 #if defined(CONFIG_HUGETLB_PAGE) || defined(CONFIG_TRANSPARENT_HUGEPAGE)
 	if (mm->context.huge_pte_count && is_hugetlb_pte(pte))
@@ -361,7 +361,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *
 		__update_mmu_tsb_insert(mm, MM_TSB_BASE, PAGE_SHIFT,
 					address, pte_val(pte));
 
-	spin_unlock_irqrestore(&mm->context.lock, flags);
+	raw_spin_unlock_irqrestore(&mm->context.lock, flags);
 }
 
 void flush_dcache_page(struct page *page)
diff --git a/arch/sparc/mm/tsb.c b/arch/sparc/mm/tsb.c
index 2cc3bce..d84d4ea 100644
--- a/arch/sparc/mm/tsb.c
+++ b/arch/sparc/mm/tsb.c
@@ -73,7 +73,7 @@ void flush_tsb_user(struct tlb_batch *tb)
 	struct mm_struct *mm = tb->mm;
 	unsigned long nentries, base, flags;
 
-	spin_lock_irqsave(&mm->context.lock, flags);
+	raw_spin_lock_irqsave(&mm->context.lock, flags);
 
 	base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
 	nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
@@ -90,14 +90,14 @@ void flush_tsb_user(struct tlb_batch *tb)
 		__flush_tsb_one(tb, HPAGE_SHIFT, base, nentries);
 	}
 #endif
-	spin_unlock_irqrestore(&mm->context.lock, flags);
+	raw_spin_unlock_irqrestore(&mm->context.lock, flags);
 }
 
 void flush_tsb_user_page(struct mm_struct *mm, unsigned long vaddr)
 {
 	unsigned long nentries, base, flags;
 
-	spin_lock_irqsave(&mm->context.lock, flags);
+	raw_spin_lock_irqsave(&mm->context.lock, flags);
 
 	base = (unsigned long) mm->context.tsb_block[MM_TSB_BASE].tsb;
 	nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
@@ -114,7 +114,7 @@ void flush_tsb_user_page(struct mm_struct *mm, unsigned long vaddr)
 		__flush_tsb_one_entry(base, vaddr, HPAGE_SHIFT, nentries);
 	}
 #endif
-	spin_unlock_irqrestore(&mm->context.lock, flags);
+	raw_spin_unlock_irqrestore(&mm->context.lock, flags);
 }
 
 #define HV_PGSZ_IDX_BASE	HV_PGSZ_IDX_8K
@@ -392,7 +392,7 @@ retry_tsb_alloc:
 	 * the lock and ask all other cpus running this address space
 	 * to run tsb_context_switch() to see the new TSB table.
 	 */
-	spin_lock_irqsave(&mm->context.lock, flags);
+	raw_spin_lock_irqsave(&mm->context.lock, flags);
 
 	old_tsb = mm->context.tsb_block[tsb_index].tsb;
 	old_cache_index =
@@ -407,7 +407,7 @@ retry_tsb_alloc:
 	 */
 	if (unlikely(old_tsb &&
 		     (rss < mm->context.tsb_block[tsb_index].tsb_rss_limit))) {
-		spin_unlock_irqrestore(&mm->context.lock, flags);
+		raw_spin_unlock_irqrestore(&mm->context.lock, flags);
 
 		kmem_cache_free(tsb_caches[new_cache_index], new_tsb);
 		return;
@@ -433,7 +433,7 @@ retry_tsb_alloc:
 	mm->context.tsb_block[tsb_index].tsb = new_tsb;
 	setup_tsb_params(mm, tsb_index, new_size);
 
-	spin_unlock_irqrestore(&mm->context.lock, flags);
+	raw_spin_unlock_irqrestore(&mm->context.lock, flags);
 
 	/* If old_tsb is NULL, we're being invoked for the first time
 	 * from init_new_context().
@@ -459,7 +459,7 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 #endif
 	unsigned int i;
 
-	spin_lock_init(&mm->context.lock);
+	raw_spin_lock_init(&mm->context.lock);
 
 	mm->context.sparc64_ctx_val = 0UL;
 
-- 
1.7.10.4

[PATCH 4/4] [V1] sparc64: convert ctx_alloc_lock raw_spinlock_t

[Allen Pais]

This patch fixes the kernel crash faced while
trying to attempt linux-stable-rt v3.10.22-rt19
on sparc64.

[ 2317.606015]  [00000000008072f4] rt_spin_lock_slowlock+0x94/0x300
[ 2317.606020]  [0000000000451d74] get_new_mmu_context+0x14/0x160
[ 2317.606026]  [0000000000806394] switch_to_pc+0xd4/0x2a0
[ 2317.606029]  [00000000008067dc] schedule+0x1c/0xc0
[ 2317.606031]  [0000000000807364] rt_spin_lock_slowlock+0x104/0x300
[ 2317.606033]  [0000000000450284] destroy_context+0x84/0x120
[ 2317.606036]  [000000000045c788] __mmdrop+0x28/0xe0
[ 2317.606045]  [00000000004bf290] rcu_process_callbacks+0x450/0x760
[ 2317.606049]  [0000000000466d48] do_current_softirqs+0x208/0x3c0
[ 2317.606051]  [0000000000466f14] run_ksoftirqd+0x14/0x40
[ 2317.606057]  [000000000048c64c] smpboot_thread_fn+0x18c/0x2e0
[ 2317.606061]  [0000000000483b5c] kthread+0x7c/0xa0
[ 2317.606069]  [00000000004060c4] ret_from_syscall+0x1c/0x2c
[ 2317.606070]  [0000000000000000]           (null)

Signed-off-by: Allen Pais <allen.pais@oracle.com>
---
 arch/sparc/include/asm/mmu_context_64.h |    2 +-
 arch/sparc/mm/init_64.c                 |   10 +++++-----
 arch/sparc/mm/tsb.c                     |    4 ++--
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/sparc/include/asm/mmu_context_64.h b/arch/sparc/include/asm/mmu_context_64.h
index 3a85624..44e393b 100644
--- a/arch/sparc/include/asm/mmu_context_64.h
+++ b/arch/sparc/include/asm/mmu_context_64.h
@@ -13,7 +13,7 @@ static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
 {
 }
 
-extern spinlock_t ctx_alloc_lock;
+extern raw_spinlock_t ctx_alloc_lock;
 extern unsigned long tlb_context_cache;
 extern unsigned long mmu_context_bmap[];
 
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
index bd5253d..ac5ae7a 100644
--- a/arch/sparc/mm/init_64.c
+++ b/arch/sparc/mm/init_64.c
@@ -661,7 +661,7 @@ void __flush_dcache_range(unsigned long start, unsigned long end)
 EXPORT_SYMBOL(__flush_dcache_range);
 
 /* get_new_mmu_context() uses "cache + 1".  */
-DEFINE_SPINLOCK(ctx_alloc_lock);
+DEFINE_RAW_SPINLOCK(ctx_alloc_lock);
 unsigned long tlb_context_cache = CTX_FIRST_VERSION - 1;
 #define MAX_CTX_NR	(1UL << CTX_NR_BITS)
 #define CTX_BMAP_SLOTS	BITS_TO_LONGS(MAX_CTX_NR)
@@ -683,7 +683,7 @@ void get_new_mmu_context(struct mm_struct *mm)
 	unsigned long orig_pgsz_bits;
 	int new_version;
 
-	spin_lock(&ctx_alloc_lock);
+	raw_spin_lock(&ctx_alloc_lock);
 	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);
@@ -719,7 +719,7 @@ void get_new_mmu_context(struct mm_struct *mm)
 out:
 	tlb_context_cache = new_ctx;
 	mm->context.sparc64_ctx_val = new_ctx | orig_pgsz_bits;
-	spin_unlock(&ctx_alloc_lock);
+	raw_spin_unlock(&ctx_alloc_lock);
 
 	if (unlikely(new_version))
 		smp_new_mmu_context_version();
@@ -2739,7 +2739,7 @@ void hugetlb_setup(struct pt_regs *regs)
 	if (tlb_type == cheetah_plus) {
 		unsigned long ctx;
 
-		spin_lock(&ctx_alloc_lock);
+		raw_spin_lock(&ctx_alloc_lock);
 		ctx = mm->context.sparc64_ctx_val;
 		ctx &= ~CTX_PGSZ_MASK;
 		ctx |= CTX_PGSZ_BASE << CTX_PGSZ0_SHIFT;
@@ -2760,7 +2760,7 @@ void hugetlb_setup(struct pt_regs *regs)
 			mm->context.sparc64_ctx_val = ctx;
 			on_each_cpu(context_reload, mm, 0);
 		}
-		spin_unlock(&ctx_alloc_lock);
+		raw_spin_unlock(&ctx_alloc_lock);
 	}
 }
 #endif
diff --git a/arch/sparc/mm/tsb.c b/arch/sparc/mm/tsb.c
index d84d4ea..9eb10b4 100644
--- a/arch/sparc/mm/tsb.c
+++ b/arch/sparc/mm/tsb.c
@@ -523,12 +523,12 @@ void destroy_context(struct mm_struct *mm)
 		free_hot_cold_page(page, 0);
 	}
 
-	spin_lock_irqsave(&ctx_alloc_lock, flags);
+	raw_spin_lock_irqsave(&ctx_alloc_lock, flags);
 
 	if (CTX_VALID(mm->context)) {
 		unsigned long nr = CTX_NRBITS(mm->context);
 		mmu_context_bmap[nr>>6] &= ~(1UL << (nr & 63));
 	}
 
-	spin_unlock_irqrestore(&ctx_alloc_lock, flags);
+	raw_spin_unlock_irqrestore(&ctx_alloc_lock, flags);
 }
-- 
1.7.10.4

Re: [PATCH 2/4] [V1] sparc64: support forced irq threading

[Sebastian Andrzej Siewior]

* Allen Pais | 2013-12-18 15:59:42 [+0530]:

Please add here some description and forward this upstream. Did this
series changed since I applied it?

>Signed-off-by: Allen Pais <allen.pais@oracle.com>

Sebastian

Re: [PATCH 2/4] [V1] sparc64: support forced irq threading

[Allen Pais]

> 
> Please add here some description and forward this upstream. Did this
> series changed since I applied it?
> 
I will add the description and send it upstream.
No, nothings changed, only that I re-based the
code to v3.10.24-rt22.

- Allen