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arm: provision page alloc debug support

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Equip arm to support ARCH_SUPPORTS_DEBUG_PAGEALLOC and
enable it by default.

Having this support means all pages freed at buddy level
would be marked as read-only and would help catch any
scribbling over free page area. Allocated pages mapping
attributes is restored to read/write.

ARCH_SUPPORTS_DEBUG_PAGEALLOC needs FORCE_PAGES which
ensures all kernel mapping are populated with page
granularity and it would ensure page level accesses  can
be rightly configured.

Change-Id: I9b23d1fb0b9594cc148b082c104da9a773c26057
Signed-off-by: Shiraz Hashim <shashim@codeaurora.org>
Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
Signed-off-by: Vijayanand Jitta <vjitta@codeaurora.org>
Signed-off-by: Qingqing Zhou <qqzhou@codeaurora.org>
This commit is contained in:
Shiraz Hashim 2017-08-11 17:49:28 +05:30 • committed by Gerrit - the friendly Code Review server
commit 61311e5672
2 changed files with 21 additions and 1 deletions
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4
arch/arm/Kconfig.debug
View file

@ -99,6 +99,10 @@ config DEBUG_USER
8 - SIGSEGV faults
16 - SIGBUS faults
config ARCH_SUPPORTS_DEBUG_PAGEALLOC
def_bool y
depends on FORCE_PAGES
config FORCE_PAGES
bool "Force lowmem to be mapped with 4K pages"
help

18
arch/arm/mm/pageattr.c
View file

@ -1,6 +1,6 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2014, The Linux Foundation. All rights reserved.
* Copyright (c) 2014,2017-2018 The Linux Foundation. All rights reserved.
*/
#include <linux/mm.h>
#include <linux/module.h>
@ -89,3 +89,19 @@ int set_memory_x(unsigned long addr, int numpages)
__pgprot(0),
__pgprot(L_PTE_XN));
}
#ifdef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC
void __kernel_map_pages(struct page *page, int numpages, int enable)
{
unsigned long addr;
if (PageHighMem(page))
return;
addr = (unsigned long) page_address(page);
if (enable)
set_memory_rw(addr, numpages);
else
set_memory_ro(addr, numpages);
}
#endif