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Message-ID: <4249d95311ec93b0a9d421ca56d69612fb1e5811.1638976229.git.christophe.leroy@csgroup.eu>
Date: Wed, 8 Dec 2021 17:18:23 +0000
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Michael Ellerman <mpe@...erman.id.au>,
"alex@...ti.fr" <alex@...ti.fr>
CC: Christophe Leroy <christophe.leroy@...roup.eu>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: [PATCH v4 10/10] powerpc/mm: Properly randomise mmap with slices
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@...roup.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 03681042b807..c0b58afb9a47 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
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