[RFC PATCH 3/8] arch/x86: Teach arch_get_unmapped_area_vmflags to handle hugetlb mappings

[Oscar Salvador <osalvador@xxxxxxx>]

We want to stop special casing hugetlb mappings and make them go
through generic channels, so teach arch_get_unmapped_area_{topdown_}vmflags
to handle those.
x86 specific hugetlb function does not set either info.start_gap or
info.align_offset so the same here for compatibility.

Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
---
 arch/x86/kernel/sys_x86_64.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/sys_x86_64.c b/arch/x86/kernel/sys_x86_64.c
index 01d7cd85ef97..aa7491f036a7 100644
--- a/arch/x86/kernel/sys_x86_64.c
+++ b/arch/x86/kernel/sys_x86_64.c
@@ -18,6 +18,7 @@
 #include <linux/random.h>
 #include <linux/uaccess.h>
 #include <linux/elf.h>
+#include <linux/hugetlb.h>
 
 #include <asm/elf.h>
 #include <asm/ia32.h>
@@ -25,8 +26,10 @@
 /*
  * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
  */
-static unsigned long get_align_mask(void)
+static unsigned long get_align_mask(struct file *filp)
 {
+	if (filp && is_file_hugepages(filp))
+		return huge_page_mask_align(filp);
 	/* handle 32- and 64-bit case with a single conditional */
 	if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
 		return 0;
@@ -49,7 +52,7 @@ static unsigned long get_align_mask(void)
  */
 static unsigned long get_align_bits(void)
 {
-	return va_align.bits & get_align_mask();
+	return va_align.bits & get_align_mask(NULL);
 }
 
 static int __init control_va_addr_alignment(char *str)
@@ -148,12 +151,15 @@ arch_get_unmapped_area_vmflags(struct file *filp, unsigned long addr, unsigned l
 	info.length = len;
 	info.low_limit = begin;
 	info.high_limit = end;
-	info.align_offset = pgoff << PAGE_SHIFT;
-	info.start_gap = stack_guard_placement(vm_flags);
+	if (!(filp && is_file_hugepages(filp))) {
+		info.align_offset = pgoff << PAGE_SHIFT;
+		info.start_gap = stack_guard_placement(vm_flags);
+	}
 	if (filp) {
-		info.align_mask = get_align_mask();
+		info.align_mask = get_align_mask(filp);
 		info.align_offset += get_align_bits();
 	}
+
 	return vm_unmapped_area(&info);
 }
 
@@ -199,7 +205,10 @@ arch_get_unmapped_area_topdown_vmflags(struct file *filp, unsigned long addr0,
 		info.low_limit = PAGE_SIZE;
 
 	info.high_limit = get_mmap_base(0);
-	info.start_gap = stack_guard_placement(vm_flags);
+	if (!(filp && is_file_hugepages(filp))) {
+		info.start_gap = stack_guard_placement(vm_flags);
+		info.align_offset = pgoff << PAGE_SHIFT;
+	}
 
 	/*
 	 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
@@ -211,9 +220,8 @@ arch_get_unmapped_area_topdown_vmflags(struct file *filp, unsigned long addr0,
 	if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
 		info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
 
-	info.align_offset = pgoff << PAGE_SHIFT;
 	if (filp) {
-		info.align_mask = get_align_mask();
+		info.align_mask = get_align_mask(filp);
 		info.align_offset += get_align_bits();
 	}
 	addr = vm_unmapped_area(&info);
-- 
2.45.2