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powerpc: Fix 64-bit BookE FP unavailable exceptions

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We were using CR0.EQ after EXCEPTION_COMMON, hoping it still
contained whether we came from userspace or kernel space.

However, under some circumstances, EXCEPTION_COMMON will
call C code and clobber non-volatile registers, so we really
need to re-load the previous MSR from the stackframe and
re-test.

While there, invert the condition to make the fast path more
obvious and remove the BUG_OPCODE which was a debugging
leftover and call .ret_from_except as we should.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Benjamin Herrenschmidt 2012-03-05 10:55:04 +11:00
parent 990118c84b
commit 9424fabf86
1 changed files with 7 additions and 6 deletions
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13
arch/powerpc/kernel/exceptions-64e.S
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@ -353,15 +353,16 @@ interrupt_end_book3e:
NORMAL_EXCEPTION_PROLOG(0x800, PROLOG_ADDITION_NONE)
/* we can probably do a shorter exception entry for that one... */
EXCEPTION_COMMON(0x800, PACA_EXGEN, INTS_KEEP)
bne 1f /* if from user, just load it up */
INTS_DISABLE_ALL
ld r12,_MSR(r1)
andi. r0,r12,MSR_PR;
beq- 1f
bl .load_up_fpu
b fast_exception_return
1: INTS_DISABLE_ALL
bl .save_nvgprs
addi r3,r1,STACK_FRAME_OVERHEAD
bl .kernel_fp_unavailable_exception
BUG_OPCODE
1: ld r12,_MSR(r1)
bl .load_up_fpu
b fast_exception_return
b .ret_from_except
/* Decrementer Interrupt */
MASKABLE_EXCEPTION(0x900, decrementer, .timer_interrupt, ACK_DEC)