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From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Michael Ellerman <mpe@ellerman.id.au>,
	alex@ghiti.fr
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>,
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	linux-mm@kvack.org
Subject: [PATCH v2 8/9] powerpc/mm: Properly randomise mmap with slices
Date: Thu, 25 Nov 2021 09:23:30 +0100	[thread overview]
Message-ID: <35c7120357b263667985684ee1df25548f7bc80e.1637828367.git.christophe.leroy@csgroup.eu> (raw)
In-Reply-To: <cover.1637828367.git.christophe.leroy@csgroup.eu>

Now that powerpc switched to default topdown mmap layout,
mm->mmap_base is properly randomised.  However
slice_find_area_bottomup() doesn't use mm->mmap_base but
uses the fixed TASK_UNMAPPED_BASE instead.

slice_find_area_bottomup() being used as a fallback to
slice_find_area_topdown(), it can't use mm->mmap_base
directly.

Instead of always using TASK_UNMAPPED_BASE as base address, leave
it to the caller. When called from slice_find_area_topdown()
TASK_UNMAPPED_BASE is used. Otherwise mm->mmap_base is used.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 arch/powerpc/mm/book3s64/slice.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/mm/book3s64/slice.c b/arch/powerpc/mm/book3s64/slice.c
index 99742dde811c..997f40184e97 100644
--- a/arch/powerpc/mm/book3s64/slice.c
+++ b/arch/powerpc/mm/book3s64/slice.c
@@ -276,20 +276,18 @@ static bool slice_scan_available(unsigned long addr,
 }
 
 static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
-					      unsigned long len,
+					      unsigned long addr, unsigned long len,
 					      const struct slice_mask *available,
 					      int psize, unsigned long high_limit)
 {
 	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
-	unsigned long addr, found, next_end;
+	unsigned long found, next_end;
 	struct vm_unmapped_area_info info;
 
 	info.flags = 0;
 	info.length = len;
 	info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
 	info.align_offset = 0;
-
-	addr = TASK_UNMAPPED_BASE;
 	/*
 	 * Check till the allow max value for this mmap request
 	 */
@@ -322,12 +320,12 @@ static unsigned long slice_find_area_bottomup(struct mm_struct *mm,
 }
 
 static unsigned long slice_find_area_topdown(struct mm_struct *mm,
-					     unsigned long len,
+					     unsigned long addr, unsigned long len,
 					     const struct slice_mask *available,
 					     int psize, unsigned long high_limit)
 {
 	int pshift = max_t(int, mmu_psize_defs[psize].shift, PAGE_SHIFT);
-	unsigned long addr, found, prev;
+	unsigned long found, prev;
 	struct vm_unmapped_area_info info;
 	unsigned long min_addr = max(PAGE_SIZE, mmap_min_addr);
 
@@ -335,8 +333,6 @@ static unsigned long slice_find_area_topdown(struct mm_struct *mm,
 	info.length = len;
 	info.align_mask = PAGE_MASK & ((1ul << pshift) - 1);
 	info.align_offset = 0;
-
-	addr = mm->mmap_base;
 	/*
 	 * If we are trying to allocate above DEFAULT_MAP_WINDOW
 	 * Add the different to the mmap_base.
@@ -377,7 +373,7 @@ static unsigned long slice_find_area_topdown(struct mm_struct *mm,
 	 * can happen with large stack limits and large mmap()
 	 * allocations.
 	 */
-	return slice_find_area_bottomup(mm, len, available, psize, high_limit);
+	return slice_find_area_bottomup(mm, TASK_UNMAPPED_BASE, len, available, psize, high_limit);
 }
 
 
@@ -386,9 +382,9 @@ static unsigned long slice_find_area(struct mm_struct *mm, unsigned long len,
 				     int topdown, unsigned long high_limit)
 {
 	if (topdown)
-		return slice_find_area_topdown(mm, len, mask, psize, high_limit);
+		return slice_find_area_topdown(mm, mm->mmap_base, len, mask, psize, high_limit);
 	else
-		return slice_find_area_bottomup(mm, len, mask, psize, high_limit);
+		return slice_find_area_bottomup(mm, mm->mmap_base, len, mask, psize, high_limit);
 }
 
 static inline void slice_copy_mask(struct slice_mask *dst,
-- 
2.33.1


  parent reply	other threads:[~2021-11-25  8:44 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-25  8:23 [PATCH v2 0/9] Convert powerpc to default topdown mmap layout Christophe Leroy
2021-11-25  8:23 ` [PATCH v2 1/9] powerpc/mm: Make slice specific to book3s/64 Christophe Leroy
2021-11-25  8:23 ` [PATCH v2 2/9] powerpc/mm: Move vma_mmu_pagesize() and hugetlb_get_unmapped_area() to slice.c Christophe Leroy
2021-11-25  8:23 ` [PATCH v2 3/9] powerpc/mm: Remove CONFIG_PPC_MM_SLICES Christophe Leroy
2021-11-25  8:23 ` [PATCH v2 4/9] powerpc/mm: Remove asm/slice.h Christophe Leroy
2021-11-25  8:23 ` [PATCH v2 5/9] powerpc/mm: Call radix__arch_get_unmapped_area() from arch_get_unmapped_area() Christophe Leroy
2021-11-25  8:23 ` [PATCH v2 6/9] mm: Allow arch specific arch_randomize_brk() with CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT Christophe Leroy
2021-11-25  8:23 ` [PATCH v2 7/9] powerpc/mm: Convert to default topdown mmap layout Christophe Leroy
2021-11-25  8:23 ` Christophe Leroy [this message]
2021-11-25  8:23 ` [PATCH v2 9/9] powerpc: Simplify and move arch_randomize_brk() Christophe Leroy
2021-11-25 10:42   ` Christophe Leroy
2021-11-26  0:36   ` kernel test robot
2021-11-26 19:23   ` kernel test robot

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