4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
commit 3aaf33bebda8d4ffcc0fc8ef39e6c1ac68823b11 upstream.
When qemu starts a kernel in a bare environment, the default SCR has
the AW and FW bits clear, which means that the kernel can't modify
the PSR A or PSR F bits, and means that FIQs and imprecise aborts are
always masked.
When running uboot under qemu, the AW and FW SCR bits are set, and the
kernel functions normally - and this is how real hardware behaves.
Fix this for qemu by ignoring the FIQ bit.
Fixes: 8bafae202c82 ("ARM: BUG if jumping to usermode address in kernel mode")
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
Cc: Alex Shi <alex.shi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kernel/entry-header.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -295,7 +295,7 @@
mov r2, sp
ldr r1, [r2, #\offset + S_PSR] @ get calling cpsr
ldr lr, [r2, #\offset + S_PC]! @ get pc
- tst r1, #0xcf
+ tst r1, #PSR_I_BIT | 0x0f
bne 1f
msr spsr_cxsf, r1 @ save in spsr_svc
#if defined(CONFIG_CPU_V6) || defined(CONFIG_CPU_32v6K)
@@ -327,7 +327,7 @@
ldr r1, [sp, #\offset + S_PSR] @ get calling cpsr
ldr lr, [sp, #\offset + S_PC] @ get pc
add sp, sp, #\offset + S_SP
- tst r1, #0xcf
+ tst r1, #PSR_I_BIT | 0x0f
bne 1f
msr spsr_cxsf, r1 @ save in spsr_svc