aboutsummaryrefslogtreecommitdiff
path: root/arch/powerpc
diff options
context:
space:
mode:
authorPaul Mackerras <paulus@samba.org>2013-04-25 17:51:40 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2013-04-26 16:08:27 +1000
commita485c70989fc6e1b002ea8c323bc3fc2f1eab722 (patch)
treeca25f92603c01e6e2dbc35b6f50fe63164a4c039 /arch/powerpc
parente04fa61214a3e586282490af7e1b023522c1472a (diff)
downloadvexpress-lsk-a485c70989fc6e1b002ea8c323bc3fc2f1eab722.tar.gz
powerpc: Fix "attempt to move .org backwards" error
Building a 64-bit powerpc kernel with PR KVM enabled currently gives this error: AS arch/powerpc/kernel/head_64.o arch/powerpc/kernel/exceptions-64s.S: Assembler messages: arch/powerpc/kernel/exceptions-64s.S:258: Error: attempt to move .org backwards make[2]: *** [arch/powerpc/kernel/head_64.o] Error 1 This happens because the MASKABLE_EXCEPTION_PSERIES macro turns into 33 instructions, but we only have space for 32 at the decrementer interrupt vector (from 0x900 to 0x980). In the code generated by the MASKABLE_EXCEPTION_PSERIES macro, we currently have two instances of the HMT_MEDIUM macro, which has the effect of setting the SMT thread priority to medium. One is the first instruction, and is overwritten by a no-op on processors where we save the PPR (processor priority register), that is, POWER7 or later. The other is after we have saved the PPR. In order to reduce the code at 0x900 by one instruction, we omit the first HMT_MEDIUM. On processors without SMT this will have no effect since HMT_MEDIUM is a no-op there. On POWER5 and RS64 machines this will mean that the first few instructions take a little longer in the case where a decrementer interrupt occurs when the hardware thread is running at low SMT priority. On POWER6 and later machines, the hardware automatically boosts the thread priority when a decrementer interrupt is taken if the thread priority was below medium, so this change won't make any difference. The alternative would be to branch out of line after saving the CFAR. However, that would incur an extra overhead on all processors, whereas the approach adopted here only adds overhead on older threaded processors. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/include/asm/exception-64s.h2
-rw-r--r--arch/powerpc/kernel/exceptions-64s.S7
2 files changed, 7 insertions, 2 deletions
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 05e6d2ee1db..8e5fae8beaf 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -414,7 +414,6 @@ label##_relon_hv: \
#define SOFTEN_NOTEST_HV(vec) _SOFTEN_TEST(EXC_HV, vec)
#define __MASKABLE_EXCEPTION_PSERIES(vec, label, h, extra) \
- HMT_MEDIUM_PPR_DISCARD; \
SET_SCRATCH0(r13); /* save r13 */ \
EXCEPTION_PROLOG_0(PACA_EXGEN); \
__EXCEPTION_PROLOG_1(PACA_EXGEN, extra, vec); \
@@ -427,6 +426,7 @@ label##_relon_hv: \
. = loc; \
.globl label##_pSeries; \
label##_pSeries: \
+ HMT_MEDIUM_PPR_DISCARD; \
_MASKABLE_EXCEPTION_PSERIES(vec, label, \
EXC_STD, SOFTEN_TEST_PR)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 82ceab4d895..80d56f094a0 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -235,6 +235,7 @@ instruction_access_slb_pSeries:
.globl hardware_interrupt_hv;
hardware_interrupt_pSeries:
hardware_interrupt_hv:
+ HMT_MEDIUM_PPR_DISCARD
BEGIN_FTR_SECTION
_MASKABLE_EXCEPTION_PSERIES(0x502, hardware_interrupt,
EXC_HV, SOFTEN_TEST_HV)
@@ -254,7 +255,11 @@ hardware_interrupt_hv:
STD_EXCEPTION_PSERIES(0x800, 0x800, fp_unavailable)
KVM_HANDLER_PR(PACA_EXGEN, EXC_STD, 0x800)
- MASKABLE_EXCEPTION_PSERIES(0x900, 0x900, decrementer)
+ . = 0x900
+ .globl decrementer_pSeries
+decrementer_pSeries:
+ _MASKABLE_EXCEPTION_PSERIES(0x900, decrementer, EXC_STD, SOFTEN_TEST_PR)
+
STD_EXCEPTION_HV(0x980, 0x982, hdecrementer)
MASKABLE_EXCEPTION_PSERIES(0xa00, 0xa00, doorbell_super)