--- /dev/null
+From: James Hogan <james.hogan@imgtec.com>
+Date: Mon, 25 Jan 2016 21:30:00 +0000
+Subject: [PATCH] MIPS: c-r4k: Use IPI calls for CM indexed cache ops
+
+The Coherence Manager (CM) can propagate address-based ("hit") cache
+operations to other cores in the coherent system, alleviating software
+of the need to use IPI calls, however indexed cache operations are not
+propagated since doing so makes no sense for separate caches.
+
+r4k_on_each_cpu() previously had a special case for CONFIG_MIPS_MT_SMP,
+intended to avoid the IPIs when the only other CPUs in the system were
+other VPEs in the same core, and hence sharing the same caches. This was
+changed by commit cccf34e9411c ("MIPS: c-r4k: Fix cache flushing for MT
+cores") to apparently handle multi-core multi-VPE systems, but it
+focussed mainly on hit cache ops, so the IPI calls were still disabled
+entirely for CM systems.
+
+This doesn't normally cause problems, but tests can be written to hit
+these corner cases by using multiple threads, or changing task
+affinities to force the process to migrate cores. For example the
+failure of mprotect RW->RX to globally sync icaches (via
+flush_cache_range) can be detected by modifying and mprotecting a code
+page on one core, and migrating to a different core to execute from it.
+
+Most of the functions called by r4k_on_each_cpu() perform cache
+operations exclusively with a single addressing-type (virtual address vs
+indexed), so add a type argument and modify the callers to pass in
+R4K_USER (user virtual addressing), R4K_KERN (global kernel virtual
+addressing) or R4K_INDEX (index into cache).
+
+local_r4k_flush_icache_range() is split up, to allow it to be called
+from the rest of the kernel, or from r4k_flush_icache_range() where it
+will choose either indexed or hit cache operations based on the size of
+the range and the cache sizes.
+
+local_r4k_flush_kernel_vmap_range() is split into two functions, each of
+which uses cache operations with a single addressing-type, with
+r4k_flush_kernel_vmap_range() making the decision whether to use indexed
+cache ops or not.
+
+Signed-off-by: James Hogan <james.hogan@imgtec.com>
+Cc: Ralf Baechle <ralf@linux-mips.org>
+Cc: Paul Burton <paul.burton@imgtec.com>
+Cc: Leonid Yegoshin <leonid.yegoshin@imgtec.com>
+Cc: linux-mips@linux-mips.org
+---
+
+--- a/arch/mips/mm/c-r4k.c
++++ b/arch/mips/mm/c-r4k.c
+@@ -40,6 +40,50 @@
+ #include <asm/mips-cm.h>
+
+ /*
++ * Bits describing what cache ops an IPI callback function may perform.
++ *
++ * R4K_USER - Virtual user address based cache operations.
++ * Ineffective on other CPUs.
++ * R4K_KERN - Virtual kernel address based cache operations (including kmap).
++ * Effective on other CPUs.
++ * R4K_INDEX - Index based cache operations.
++ * Effective on other CPUs.
++ */
++
++#define R4K_USER BIT(0)
++#define R4K_KERN BIT(1)
++#define R4K_INDEX BIT(2)
++
++#ifdef CONFIG_SMP
++/* The Coherence manager propagates address-based cache ops to other cores */
++#define r4k_hit_globalized mips_cm_present()
++#define r4k_index_globalized 0
++#else
++/* If there's only 1 CPU, then all cache ops are globalized to that 1 CPU */
++#define r4k_hit_globalized 1
++#define r4k_index_globalized 1
++#endif
++
++/**
++ * r4k_op_needs_ipi() - Decide if a cache op needs to be done on every core.
++ * @type: Type of cache operations (R4K_USER, R4K_KERN or R4K_INDEX).
++ *
++ * Returns: 1 if the cache operation @type should be done on every core in
++ * the system.
++ * 0 if the cache operation @type is globalized and only needs to
++ * be performed on a simple CPU.
++ */
++static inline bool r4k_op_needs_ipi(unsigned int type)
++{
++ /*
++ * If hardware doesn't globalize the required cache ops we must use IPIs
++ * to do so.
++ */
++ return (type & R4K_KERN && !r4k_hit_globalized) ||
++ (type & R4K_INDEX && !r4k_index_globalized);
++}
++
++/*
+ * Special Variant of smp_call_function for use by cache functions:
+ *
+ * o No return value
+@@ -48,19 +92,11 @@
+ * primary cache.
+ * o doesn't disable interrupts on the local CPU
+ */
+-static inline void r4k_on_each_cpu(void (*func) (void *info), void *info)
++static inline void r4k_on_each_cpu(unsigned int type,
++ void (*func) (void *info), void *info)
+ {
+ preempt_disable();
+-
+- /*
+- * The Coherent Manager propagates address-based cache ops to other
+- * cores but not index-based ops. However, r4k_on_each_cpu is used
+- * in both cases so there is no easy way to tell what kind of op is
+- * executed to the other cores. The best we can probably do is
+- * to restrict that call when a CM is not present because both
+- * CM-based SMP protocols (CMP & CPS) restrict index-based cache ops.
+- */
+- if (!mips_cm_present())
++ if (r4k_op_needs_ipi(type))
+ smp_call_function_many(&cpu_foreign_map, func, info, 1);
+ func(info);
+ preempt_enable();
+@@ -456,7 +492,7 @@ static inline void local_r4k___flush_cac
+
+ static void r4k___flush_cache_all(void)
+ {
+- r4k_on_each_cpu(local_r4k___flush_cache_all, NULL);
++ r4k_on_each_cpu(R4K_INDEX, local_r4k___flush_cache_all, NULL);
+ }
+
+ static inline int has_valid_asid(const struct mm_struct *mm)
+@@ -503,7 +539,7 @@ static void r4k_flush_cache_range(struct
+ int exec = vma->vm_flags & VM_EXEC;
+
+ if (cpu_has_dc_aliases || (exec && !cpu_has_ic_fills_f_dc))
+- r4k_on_each_cpu(local_r4k_flush_cache_range, vma);
++ r4k_on_each_cpu(R4K_INDEX, local_r4k_flush_cache_range, vma);
+ }
+
+ static inline void local_r4k_flush_cache_mm(void * args)
+@@ -535,7 +571,7 @@ static void r4k_flush_cache_mm(struct mm
+ if (!cpu_has_dc_aliases)
+ return;
+
+- r4k_on_each_cpu(local_r4k_flush_cache_mm, mm);
++ r4k_on_each_cpu(R4K_INDEX, local_r4k_flush_cache_mm, mm);
+ }
+
+ struct flush_cache_page_args {
+@@ -629,7 +665,7 @@ static void r4k_flush_cache_page(struct
+ args.addr = addr;
+ args.pfn = pfn;
+
+- r4k_on_each_cpu(local_r4k_flush_cache_page, &args);
++ r4k_on_each_cpu(R4K_KERN, local_r4k_flush_cache_page, &args);
+ }
+
+ static inline void local_r4k_flush_data_cache_page(void * addr)
+@@ -642,18 +678,23 @@ static void r4k_flush_data_cache_page(un
+ if (in_atomic())
+ local_r4k_flush_data_cache_page((void *)addr);
+ else
+- r4k_on_each_cpu(local_r4k_flush_data_cache_page, (void *) addr);
++ r4k_on_each_cpu(R4K_KERN, local_r4k_flush_data_cache_page,
++ (void *) addr);
+ }
+
+ struct flush_icache_range_args {
+ unsigned long start;
+ unsigned long end;
++ unsigned int type;
+ };
+
+-static inline void local_r4k_flush_icache_range(unsigned long start, unsigned long end)
++static inline void __local_r4k_flush_icache_range(unsigned long start,
++ unsigned long end,
++ unsigned int type)
+ {
+ if (!cpu_has_ic_fills_f_dc) {
+- if (end - start >= dcache_size) {
++ if (type == R4K_INDEX ||
++ (type & R4K_INDEX && end - start >= dcache_size)) {
+ r4k_blast_dcache();
+ } else {
+ R4600_HIT_CACHEOP_WAR_IMPL;
+@@ -661,7 +702,8 @@ static inline void local_r4k_flush_icach
+ }
+ }
+
+- if (end - start > icache_size)
++ if (type == R4K_INDEX ||
++ (type & R4K_INDEX && end - start > icache_size))
+ r4k_blast_icache();
+ else {
+ switch (boot_cpu_type()) {
+@@ -687,23 +729,59 @@ static inline void local_r4k_flush_icach
+ #endif
+ }
+
++static inline void local_r4k_flush_icache_range(unsigned long start,
++ unsigned long end)
++{
++ __local_r4k_flush_icache_range(start, end, R4K_KERN | R4K_INDEX);
++}
++
+ static inline void local_r4k_flush_icache_range_ipi(void *args)
+ {
+ struct flush_icache_range_args *fir_args = args;
+ unsigned long start = fir_args->start;
+ unsigned long end = fir_args->end;
++ unsigned int type = fir_args->type;
+
+- local_r4k_flush_icache_range(start, end);
++ __local_r4k_flush_icache_range(start, end, type);
+ }
+
+ static void r4k_flush_icache_range(unsigned long start, unsigned long end)
+ {
+ struct flush_icache_range_args args;
++ unsigned long size, cache_size;
+
+ args.start = start;
+ args.end = end;
++ args.type = R4K_KERN | R4K_INDEX;
+
+- r4k_on_each_cpu(local_r4k_flush_icache_range_ipi, &args);
++ if (in_atomic()) {
++ /*
++ * We can't do blocking IPI calls from atomic context, so fall
++ * back to pure address-based cache ops if they globalize.
++ */
++ if (!r4k_index_globalized && r4k_hit_globalized) {
++ args.type &= ~R4K_INDEX;
++ } else {
++ /* Just do it locally instead. */
++ local_r4k_flush_icache_range(start, end);
++ instruction_hazard();
++ return;
++ }
++ } else if (!r4k_index_globalized && r4k_hit_globalized) {
++ /*
++ * If address-based cache ops are globalized, then we may be
++ * able to avoid the IPI for small flushes.
++ */
++ size = start - end;
++ cache_size = icache_size;
++ if (!cpu_has_ic_fills_f_dc) {
++ size *= 2;
++ cache_size += dcache_size;
++ }
++ if (size <= cache_size)
++ args.type &= ~R4K_INDEX;
++ }
++ r4k_on_each_cpu(args.type, local_r4k_flush_icache_range_ipi, &args);
+ instruction_hazard();
+ }
+
+@@ -823,7 +901,12 @@ static void local_r4k_flush_cache_sigtra
+
+ static void r4k_flush_cache_sigtramp(unsigned long addr)
+ {
+- r4k_on_each_cpu(local_r4k_flush_cache_sigtramp, (void *) addr);
++ /*
++ * FIXME this is a bit broken when !r4k_hit_globalized, since the user
++ * code probably won't be mapped on other CPUs, so if the process is
++ * migrated, it could end up hitting stale icache lines.
++ */
++ r4k_on_each_cpu(R4K_USER, local_r4k_flush_cache_sigtramp, (void *)addr);
+ }
+
+ static void r4k_flush_icache_all(void)
+@@ -837,6 +920,15 @@ struct flush_kernel_vmap_range_args {
+ int size;
+ };
+
++static inline void local_r4k_flush_kernel_vmap_range_index(void *args)
++{
++ /*
++ * Aliases only affect the primary caches so don't bother with
++ * S-caches or T-caches.
++ */
++ r4k_blast_dcache();
++}
++
+ static inline void local_r4k_flush_kernel_vmap_range(void *args)
+ {
+ struct flush_kernel_vmap_range_args *vmra = args;
+@@ -847,12 +939,8 @@ static inline void local_r4k_flush_kerne
+ * Aliases only affect the primary caches so don't bother with
+ * S-caches or T-caches.
+ */
+- if (cpu_has_safe_index_cacheops && size >= dcache_size)
+- r4k_blast_dcache();
+- else {
+- R4600_HIT_CACHEOP_WAR_IMPL;
+- blast_dcache_range(vaddr, vaddr + size);
+- }
++ R4600_HIT_CACHEOP_WAR_IMPL;
++ blast_dcache_range(vaddr, vaddr + size);
+ }
+
+ static void r4k_flush_kernel_vmap_range(unsigned long vaddr, int size)
+@@ -862,7 +950,12 @@ static void r4k_flush_kernel_vmap_range(
+ args.vaddr = (unsigned long) vaddr;
+ args.size = size;
+
+- r4k_on_each_cpu(local_r4k_flush_kernel_vmap_range, &args);
++ if (cpu_has_safe_index_cacheops && size >= dcache_size)
++ r4k_on_each_cpu(R4K_INDEX,
++ local_r4k_flush_kernel_vmap_range_index, NULL);
++ else
++ r4k_on_each_cpu(R4K_KERN, local_r4k_flush_kernel_vmap_range,
++ &args);
+ }
+
+ static inline void rm7k_erratum31(void)
projects / openwrt / staging / stintel.git / commitdiff