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ARM: avoid faulting on qemu

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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@armlinux.org.uk>
Cc: Alex Shi <alex.shi@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Russell King 2017-11-27 11:22:42 +00:00 • committed by Greg Kroah-Hartman
parent af1d172396
commit dd8c78e250
1 changed files with 2 additions and 2 deletions
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4
arch/arm/kernel/entry-header.S
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@ -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