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ARM: 9131/1: mm: Fix PXN process with LPAE feature

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When user code execution with privilege mode, it will lead to
infinite loop in the page fault handler if ARM_LPAE enabled,

The issue could be reproduced with
  "echo EXEC_USERSPACE > /sys/kernel/debug/provoke-crash/DIRECT"

As Permission fault shows in ARM spec,
  IFSR format when using the Short-descriptor translation table format
    Permission fault:       01101 First level      01111 Second level
  IFSR format when using the Long-descriptor translation table format
    Permission fault:       0011LL LL bits indicate levelb.

Add is_permission_fault() function to check permission fault and die
if permission fault occurred under instruction fault in do_page_fault().

Fixes: 1d4d37159d ("ARM: 8235/1: Support for the PXN CPU feature on ARMv7")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Wang Kefeng 2021-09-22 14:56:32 +01:00 • committed by Russell King (Oracle)
parent 2e707106fa
commit abc25bbcb5
2 changed files with 23 additions and 1 deletions
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4
arch/arm/mm/fault.h
View file

@ -14,6 +14,8 @@
#ifdef CONFIG_ARM_LPAE
#define FSR_FS_AEA 17
#define FS_PERM_NOLL 0xC
#define FS_PERM_NOLL_MASK 0x3C
static inline int fsr_fs(unsigned int fsr)
{
@ -21,6 +23,8 @@ static inline int fsr_fs(unsigned int fsr)
}
#else
#define FSR_FS_AEA 22
#define FS_L1_PERM 0xD
#define FS_L2_PERM 0xF
static inline int fsr_fs(unsigned int fsr)
{