kernel/arm: add memory barriers for page table ops

Introduce memory barriers according to ARMARM,
section G.5.3 TLB maintenance operations and barriers

Sequence for mapping memory in (both L1 and L2):
* DSB
* Invalidate i-cache (TODO)
* Insert new entry in page directory / page table
* DSB
* ISB

Sequence for mapping memory out:
* Remove page table entry
* DSB
* Invalidate TLB entry
* DSB
* ISB

Sequence for updating a page table entry:
* Update page table entry
* DSB
* Invalidate TLB entry
* Invalidate branch predictor (TODO)
* DSB
* ISB

Note: i-cache invalidation and branch predictor invalidation is
not implemented yet as this commit focuses on implementing memory
barriers.

Change-Id: I192fa80f6b43117236a4be6fa8c988afca90e015
Reviewed-on: https://review.haiku-os.org/c/haiku/+/5241
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Fredrik Holmqvist <fredrik.holmqvist@gmail.com>

headers/private/kernel/arch/arm/arch_cpu.h

@@ -11,23 +11,9 @@
 	// TODO: Could be 32-bits sometimes?
 
 
-#if __ARM_ARCH__ <= 5
-#define isb() __asm__ __volatile__("" : : : "memory")
-#define dsb() __asm__ __volatile__("mcr p15, 0, %0, c7, c10, 4" \
-    : : "r" (0) : "memory")
-#define dmb() __asm__ __volatile__("" : : : "memory")
-#elif __ARM_ARCH__ == 6
-#define isb() __asm__ __volatile__("mcr p15, 0, %0, c7, c5, 4" \
-    : : "r" (0) : "memory")
-#define dsb() __asm__ __volatile__("mcr p15, 0, %0, c7, c10, 4" \
-    : : "r" (0) : "memory")
-#define dmb() __asm__ __volatile__("mcr p15, 0, %0, c7, c10, 5" \
-    : : "r" (0) : "memory")
-#else /* ARMv7+ */
 #define isb() __asm__ __volatile__("isb" : : : "memory")
 #define dsb() __asm__ __volatile__("dsb" : : : "memory")
 #define dmb() __asm__ __volatile__("dmb" : : : "memory")
-#endif
 
 #define set_ac()
 #define clear_ac()
@@ -98,6 +84,7 @@ extern addr_t arm_get_fp(void);
 extern int mmu_read_c1(void);
 extern int mmu_write_c1(int val);
 
+void arch_cpu_invalidate_TLB_page(addr_t page);
 
 static inline void
 arch_cpu_pause(void)

src/system/kernel/arch/arm/arch_cpu.cpp

@@ -117,34 +117,70 @@ arch_cpu_memory_write_barrier(void)
 }
 
 
+void
+arch_cpu_invalidate_TLB_page(addr_t page)
+{
+	// ensure visibility of the update to translation table walks
+	dsb();
+
+	// TLBIMVAIS(page)
+	asm volatile ("mcr p15, 0, %0, c8, c3, 1"
+		: : "r" (page));
+
+	// ensure completion of TLB invalidation
+	dsb();
+	isb();
+}
+
 void
 arch_cpu_invalidate_TLB_range(addr_t start, addr_t end)
 {
+	// ensure visibility of the update to translation table walks
+	dsb();
+
 	int32 num_pages = end / B_PAGE_SIZE - start / B_PAGE_SIZE;
 	while (num_pages-- >= 0) {
 		asm volatile ("mcr p15, 0, %[c8format], c8, c6, 1"
 			: : [c8format] "r" (start) );
 		start += B_PAGE_SIZE;
 	}
+
+	// ensure completion of TLB invalidation
+	dsb();
+	isb();
 }
 
 
 void
 arch_cpu_invalidate_TLB_list(addr_t pages[], int num_pages)
 {
+	// ensure visibility of the update to translation table walks
+	dsb();
+
 	for (int i = 0; i < num_pages; i++) {
 		asm volatile ("mcr p15, 0, %[c8format], c8, c6, 1":
 			: [c8format] "r" (pages[i]) );
 	}
+
+	// ensure completion of TLB invalidation
+	dsb();
+	isb();
 }
 
 
 void
 arch_cpu_global_TLB_invalidate(void)
 {
+	// ensure visibility of the update to translation table walks
+	dsb();
+
 	uint32 Rd = 0;
 	asm volatile ("mcr p15, 0, %[c8format], c8, c7, 0"
 		: : [c8format] "r" (Rd) );
+
+	// ensure completion of TLB invalidation
+	dsb();
+	isb();
 }
 
 

src/system/kernel/arch/arm/paging/32bit/ARMPagingMethod32Bit.cpp

@@ -185,8 +185,7 @@ ARMPagingMethod32Bit::PhysicalPageSlotPool::Map(phys_addr_t physicalAddress,
 		| ARM_MMU_L2_FLAG_B | ARM_MMU_L2_FLAG_C
 		| ARM_MMU_L2_FLAG_AP_KRW | ARM_MMU_L2_FLAG_XN;
 
-	arch_cpu_invalidate_TLB_range(virtualAddress, virtualAddress + B_PAGE_SIZE);
-//	invalidate_TLB(virtualAddress);
+	arch_cpu_invalidate_TLB_page(virtualAddress);
 }
 
 
@@ -396,12 +395,12 @@ ARMPagingMethod32Bit::MapEarly(kernel_args* args, addr_t virtualAddress,
 			"pgtable. phys=%#" B_PRIxPHYSADDR ", virt=%#" B_PRIxADDR "\n",
 			pgtable_phys, pgtable_virt);
 
+		// zero it out in it's new mapping
+		memset((void*)pgtable_virt, 0, B_PAGE_SIZE);
+
 		// put it in the pgdir
 		e = &fKernelVirtualPageDirectory[index];
 		PutPageTableInPageDir(e, pgtable_phys, attributes);
-
-		// zero it out in it's new mapping
-		memset((void*)pgtable_virt, 0, B_PAGE_SIZE);
 	}
 
 	phys_addr_t ptEntryPhys = fKernelVirtualPageDirectory[index] & ARM_PDE_ADDRESS_MASK;
@@ -493,14 +492,12 @@ ARMPagingMethod32Bit::IsKernelPageAccessible(addr_t virtualAddress,
 ARMPagingMethod32Bit::PutPageTableInPageDir(page_directory_entry* entry,
 	phys_addr_t pgtablePhysical, uint32 attributes)
 {
+	dsb();
+
 	*entry = (pgtablePhysical & ARM_PDE_ADDRESS_MASK) | ARM_MMU_L1_TYPE_COARSE;
-		// TODO: we ignore the attributes of the page table - for compatibility
-		// with BeOS we allow having user accessible areas in the kernel address
-		// space. This is currently being used by some drivers, mainly for the
-		// frame buffer. Our current real time data implementation makes use of
-		// this fact, too.
-		// We might want to get rid of this possibility one day, especially if
-		// we intend to port it to a platform that does not support this.
+
+	dsb();
+	isb();
 }
 
 
@@ -517,6 +514,9 @@ ARMPagingMethod32Bit::PutPageTableEntryInTable(page_table_entry* entry,
 
 	// put it in the page table
 	*(volatile page_table_entry*)entry = page;
+
+	dsb();
+	isb();
 }