linux-kernel - [RFC PATCH v1 49/50] arch/x86/entry/vdso/vma.c: Use get_random_max32() for vdso

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Message-Id: <202003281643.02SGhQZ8022500@sdf.org>
Date:   Fri, 29 Nov 2019 19:05:57 -0500
From:   George Spelvin <lkml@....org>
To:     linux-kernel@...r.kernel.org, lkml@....org
Cc:     Ingo Molnar <mingo@...nel.org>, Andy Lutomirski <luto@...nel.org>
Subject: [RFC PATCH v1 49/50] arch/x86/entry/vdso/vma.c: Use
 get_random_max32() for vdso_addr

Which is faster and more uniform than get_random_int() % range.

Signed-off-by: George Spelvin <lkml@....org>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Andy Lutomirski <luto@...nel.org>
---
 arch/x86/entry/vdso/vma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c
index f5937742b2901..beb4ef8f85987 100644
--- a/arch/x86/entry/vdso/vma.c
+++ b/arch/x86/entry/vdso/vma.c
@@ -227,7 +227,7 @@ static unsigned long vdso_addr(unsigned long start, unsigned len)
 	end -= len;
 
 	if (end > start) {
-		offset = get_random_int() % (((end - start) >> PAGE_SHIFT) + 1);
+		offset = get_random_max32(((end - start) >> PAGE_SHIFT) + 1);
 		addr = start + (offset << PAGE_SHIFT);
 	} else {
 		addr = start;
-- 
2.26.0