ANDROID: vendor_hooks: Add hooks for reducing virtual address fragmentation

When running 32-bit apps for a long time, virtual address becomes fragmented which can lead to allocation failures when a large virtually-contiguous area is requested.
Add hooks to implement pools to cluster together small-sized virtual address mappings.
Add hooks to implement reserved virtual address zone with usage restrictions controlled by vendor hooks.
These hooks help in controlling virtual address space fragmentation.

Bug: 187259935

Signed-off-by: xieliujie <xieliujie@oppo.com>
Change-Id: I48c057041f9c7b8c5ab0af305f0cd87a039d0447

drivers/android/vendor_hooks.c

@@ -231,6 +231,9 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_set_module_permit_after_init);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_rvh_util_est_update);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_meminfo_proc_show);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_exit_mm);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_get_unmapped_area_from_anti_fragment_pool);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_exclude_reserved_zone);
+EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_get_unmapped_area_include_reserved_zone);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_alloc_pages_slowpath);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_show_mem);
 EXPORT_TRACEPOINT_SYMBOL_GPL(android_vh_print_slabinfo_header);

include/trace/hooks/mm.h

@@ -47,6 +47,17 @@ DECLARE_HOOK(android_vh_meminfo_proc_show,
 DECLARE_HOOK(android_vh_exit_mm,
 	TP_PROTO(struct mm_struct *mm),
 	TP_ARGS(mm));
+DECLARE_HOOK(android_vh_get_unmapped_area_from_anti_fragment_pool,
+	TP_PROTO(struct mm_struct *mm, struct vm_unmapped_area_info *info,
+		unsigned long *addr),
+	TP_ARGS(mm, info, addr));
+DECLARE_HOOK(android_vh_exclude_reserved_zone,
+	TP_PROTO(struct mm_struct *mm, struct vm_unmapped_area_info *info),
+	TP_ARGS(mm, info));
+DECLARE_HOOK(android_vh_get_unmapped_area_include_reserved_zone,
+	TP_PROTO(struct mm_struct *mm, struct vm_unmapped_area_info *info,
+		unsigned long *addr),
+	TP_ARGS(mm, info, addr));
 DECLARE_HOOK(android_vh_show_mem,
 	TP_PROTO(unsigned int filter, nodemask_t *nodemask),
 	TP_ARGS(filter, nodemask));

mm/mmap.c

@@ -55,7 +55,8 @@
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/mmap.h>
-
+#undef CREATE_TRACE_POINTS
+#include <trace/hooks/mm.h>
 #include "internal.h"
 
 #ifndef arch_mmap_check
@@ -2093,12 +2094,17 @@ static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	unsigned long length, low_limit, high_limit, gap_start, gap_end;
+	unsigned long addr;
 
 	/* Adjust search length to account for worst case alignment overhead */
 	length = info->length + info->align_mask;
 	if (length < info->length)
 		return -ENOMEM;
 
+	trace_android_vh_get_unmapped_area_from_anti_fragment_pool(mm, info, &addr);
+	if (addr)
+		return addr;
+
 	/*
 	 * Adjust search limits by the desired length.
 	 * See implementation comment at top of unmapped_area().
@@ -2301,6 +2307,7 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 	info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
 	info.align_mask = 0;
 	info.align_offset = 0;
+	trace_android_vh_exclude_reserved_zone(mm, &info);
 	addr = vm_unmapped_area(&info);
 
 	/*
@@ -2317,6 +2324,8 @@ arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 		addr = vm_unmapped_area(&info);
 	}
 
+	trace_android_vh_get_unmapped_area_include_reserved_zone(mm, &info, &addr);
+
 	return addr;
 }
 #endif