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| author | Vladimir Murzin <vladimir.murzin@arm.com> | 2019-01-25 17:18:37 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-05 23:31:37 +0300 |
| commit | cbe71d9577d3b4c971abf26e9993ed05040c387f (patch) | |
| tree | 0f3a1a712fbe1092cf18cc8e4bd5a50523c339ed /arch/arm | |
| parent | e7bde5902e78923f5e8129f68c0fea955e62e27b (diff) | |
| download | linux-cbe71d9577d3b4c971abf26e9993ed05040c387f.tar.xz | |
ARM: 8830/1: NOMMU: Toggle only bits in EXC_RETURN we are really care of
[ Upstream commit 72cd4064fccaae15ab84d40d4be23667402df4ed ]
ARMv8M introduces support for Security extension to M class, among
other things it affects exception handling, especially, encoding of
EXC_RETURN.
The new bits have been added:
Bit [6] Secure or Non-secure stack
Bit [5] Default callee register stacking
Bit [0] Exception Secure
which conflicts with hard-coded value of EXC_RETURN:
In fact, we only care of few bits:
Bit [3] Mode (0 - Handler, 1 - Thread)
Bit [2] Stack pointer selection (0 - Main, 1 - Process)
We can toggle only those bits and left other bits as they were on
exception entry.
It is basically, what patch does - saves EXC_RETURN when we do
transition form Thread to Handler mode (it is first svc), so later
saved value is used instead of EXC_RET_THREADMODE_PROCESSSTACK.
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/include/asm/v7m.h | 2 | ||||
| -rw-r--r-- | arch/arm/kernel/entry-header.S | 3 | ||||
| -rw-r--r-- | arch/arm/kernel/entry-v7m.S | 4 | ||||
| -rw-r--r-- | arch/arm/mm/proc-v7m.S | 3 |
4 files changed, 10 insertions, 2 deletions
diff --git a/arch/arm/include/asm/v7m.h b/arch/arm/include/asm/v7m.h index e6d9e29fcae4..6416fd3a3894 100644 --- a/arch/arm/include/asm/v7m.h +++ b/arch/arm/include/asm/v7m.h @@ -49,7 +49,7 @@ * (0 -> msp; 1 -> psp). Bits [1:0] are fixed to 0b01. */ #define EXC_RET_STACK_MASK 0x00000004 -#define EXC_RET_THREADMODE_PROCESSSTACK 0xfffffffd +#define EXC_RET_THREADMODE_PROCESSSTACK (3 << 2) /* Cache related definitions */ diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S index 773424843d6e..62db1c9746cb 100644 --- a/arch/arm/kernel/entry-header.S +++ b/arch/arm/kernel/entry-header.S @@ -127,7 +127,8 @@ */ .macro v7m_exception_slow_exit ret_r0 cpsid i - ldr lr, =EXC_RET_THREADMODE_PROCESSSTACK + ldr lr, =exc_ret + ldr lr, [lr] @ read original r12, sp, lr, pc and xPSR add r12, sp, #S_IP diff --git a/arch/arm/kernel/entry-v7m.S b/arch/arm/kernel/entry-v7m.S index abcf47848525..19d2dcd6530d 100644 --- a/arch/arm/kernel/entry-v7m.S +++ b/arch/arm/kernel/entry-v7m.S @@ -146,3 +146,7 @@ ENTRY(vector_table) .rept CONFIG_CPU_V7M_NUM_IRQ .long __irq_entry @ External Interrupts .endr + .align 2 + .globl exc_ret +exc_ret: + .space 4 diff --git a/arch/arm/mm/proc-v7m.S b/arch/arm/mm/proc-v7m.S index 47a5acc64433..92e84181933a 100644 --- a/arch/arm/mm/proc-v7m.S +++ b/arch/arm/mm/proc-v7m.S @@ -139,6 +139,9 @@ __v7m_setup_cont: cpsie i svc #0 1: cpsid i + ldr r0, =exc_ret + orr lr, lr, #EXC_RET_THREADMODE_PROCESSSTACK + str lr, [r0] ldmia sp, {r0-r3, r12} str r5, [r12, #11 * 4] @ restore the original SVC vector entry mov lr, r6 @ restore LR |