[OpenBIOS] [PATCH, RFC] ppc: Turn 32-bit ppc64 into a config option, to be deprecated
Andreas Färber
andreas.faerber at web.de
Wed Nov 17 20:45:03 CET 2010
Am 17.11.2010 um 02:32 schrieb Alexander Graf:
> On 14.11.2010, at 02:48, Andreas Färber wrote:
>
>> Having 64-bit support as an option allows users to disable
>> and test it before it gets officially removed.
>>
>> Fork single-bitness macros EXCEPTION_{PREAMBLE,EPILOGUE}:
>> Use assembler macros for things that are constant to avoid
>> ; and \, and use preprocessor macros to handle differences.
>> Adopt QEMU coding style for new code.
>>
>> Functional changes for ppc64:
>> * Don't clear MSR in preamble.
>> * Just save the minimum number of registers since 64-bit code will
>> save the full registers.
>> * Reserve 48 bytes of stack frame space for ppc64, according to
>> 64-bit PowerPC ELF ABI supplement 1.9.
>> * Use RFI macro.
>>
>> Cc: Alexander Graf <agraf at suse.de>
>> Signed-off-by: Andreas Färber <andreas.faerber at web.de>
>> ---
>> arch/ppc/qemu/init.c | 4 ++
>> arch/ppc/qemu/start.S | 92 ++++++++++++++++++++++++++++++
>> +++++++++-
>> config/examples/ppc_config.xml | 1 +
>> 3 files changed, 96 insertions(+), 1 deletions(-)
>>
>> diff --git a/arch/ppc/qemu/init.c b/arch/ppc/qemu/init.c
>> index 0b781d9..d17c843 100644
>> --- a/arch/ppc/qemu/init.c
>> +++ b/arch/ppc/qemu/init.c
>> @@ -303,6 +303,7 @@ cpu_g4_init(const struct cpudef *cpu)
>> fword("finish-device");
>> }
>>
>> +#ifdef CONFIG_PPC_64BITSUPPORT
>> /* In order to get 64 bit aware handlers that rescue all our
>> GPRs from getting truncated to 32 bits, we need to patch the
>> existing handlers so they jump to our 64 bit aware ones. */
>> @@ -322,6 +323,7 @@ ppc64_patch_handlers(void)
>> asm ( "icbi 0, %0" : : "r"(dsi) );
>> asm ( "icbi 0, %0" : : "r"(isi) );
>> }
>> +#endif
>>
>> static void
>> cpu_970_init(const struct cpudef *cpu)
>> @@ -341,10 +343,12 @@ cpu_970_init(const struct cpudef *cpu)
>>
>> fword("finish-device");
>>
>> +#ifdef CONFIG_PPC_64BITSUPPORT
>> /* The 970 is a PPC64 CPU, so we need to activate
>> * 64bit aware interrupt handlers */
>>
>> ppc64_patch_handlers();
>> +#endif
>>
>> /* The 970 also implements the HIOR which we need to set to 0 */
>>
>> diff --git a/arch/ppc/qemu/start.S b/arch/ppc/qemu/start.S
>> index e86bdfd..6cf20cf 100644
>> --- a/arch/ppc/qemu/start.S
>> +++ b/arch/ppc/qemu/start.S
>> @@ -14,6 +14,7 @@
>> *
>> */
>>
>> +#include "autoconf.h"
>> #include "asm/asmdefs.h"
>> #include "asm/processor.h"
>>
>> @@ -24,6 +25,8 @@
>> #define ILLEGAL_VECTOR( v ) .org __vectors + v ; vector__##v: bl
>> trap_error ;
>> #define VECTOR( v, dummystr ) .org __vectors + v ; vector__##v
>>
>> +#ifdef CONFIG_PPC_64BITSUPPORT
>> +
>> /* We're trying to use the same code for the ppc32 and ppc64
>> handlers here.
>> * On ppc32 we only save/restore the registers, C considers volatile.
>> *
>> @@ -176,6 +179,89 @@
>> #undef stl
>> #undef ll
>>
>> +#else
>> +
>> +#ifdef __powerpc64__
>> +
>> +#define ULONG_SIZE 8
>> +#define STACKFRAME_MINSIZE 48
>> +#define stl std
>> +#define ll ld
>> +
>> +#else
>> +
>> +#define ULONG_SIZE 4
>> +#define STACKFRAME_MINSIZE 16
>> +#define stl stw
>> +#define ll lwz
>> +
>> +#endif
>> +
>> +.macro EXCEPTION_PREAMBLE
>> + mtsprg1 r1 /* scratch */
>> + mfsprg0 r1 /* exception stack in sprg0 */
>> + addi r1, r1, -(20 * ULONG_SIZE) /* push exception frame */
>> +
>> + stl r0, ( 0 * ULONG_SIZE)(r1) /* save r0 */
>> + mfsprg1 r0
>> + stl r0, ( 1 * ULONG_SIZE)(r1) /* save r1 */
>> + stl r2, ( 2 * ULONG_SIZE)(r1) /* save r2 */
>> + stl r3, ( 3 * ULONG_SIZE)(r1) /* save r3 */
>> + stl r4, ( 4 * ULONG_SIZE)(r1)
>> + stl r5, ( 5 * ULONG_SIZE)(r1)
>> + stl r6, ( 6 * ULONG_SIZE)(r1)
>> + stl r7, ( 7 * ULONG_SIZE)(r1)
>> + stl r8, ( 8 * ULONG_SIZE)(r1)
>> + stl r9, ( 9 * ULONG_SIZE)(r1)
>> + stl r10, (10 * ULONG_SIZE)(r1)
>> + stl r11, (11 * ULONG_SIZE)(r1)
>> + stl r12, (12 * ULONG_SIZE)(r1)
>> +
>> + mflr r0
>> + stl r0, (13 * ULONG_SIZE)(r1)
>> + mfcr r0
>> + stl r0, (14 * ULONG_SIZE)(r1)
>> + mfctr r0
>> + stl r0, (15 * ULONG_SIZE)(r1)
>> + mfxer r0
>> + stl r0, (16 * ULONG_SIZE)(r1)
>> +
>> + /* 76(r1) unused */
This comment is obviously outdated, just like in the old code path.
>> +
>> + addi r1, r1, -STACKFRAME_MINSIZE /* C ABI saves LR and SP */
>> +.endm
>> +
>> +.macro EXCEPTION_EPILOGUE
>> + addi r1, r1, STACKFRAME_MINSIZE /* pop ABI frame */
>> +
>> + ll r0, (13 * ULONG_SIZE)(r1)
>> + mtlr r0
>> + ll r0, (14 * ULONG_SIZE)(r1)
>> + mtcr r0
>> + ll r0, (15 * ULONG_SIZE)(r1)
>> + mtctr r0
>> + ll r0, (16 * ULONG_SIZE)(r1)
>> + mtxer r0
>> +
>> + ll r0, ( 0 * ULONG_SIZE)(r1)
>> + ll r2, ( 2 * ULONG_SIZE)(r1)
>> + ll r3, ( 3 * ULONG_SIZE)(r1)
>> + ll r4, ( 4 * ULONG_SIZE)(r1)
>> + ll r5, ( 5 * ULONG_SIZE)(r1)
>> + ll r6, ( 6 * ULONG_SIZE)(r1)
>> + ll r7, ( 7 * ULONG_SIZE)(r1)
>> + ll r8, ( 8 * ULONG_SIZE)(r1)
>> + ll r9, ( 9 * ULONG_SIZE)(r1)
>> + ll r10, (10 * ULONG_SIZE)(r1)
>> + ll r11, (11 * ULONG_SIZE)(r1)
>> + ll r12, (12 * ULONG_SIZE)(r1)
>> +
>> + ll r1, ( 1 * ULONG_SIZE)(r1) /* restore stack at last */
>> + RFI
>> +.endm
>
>
> I don't think this really belongs in this patch, no? :)
--verbose please. The description is pretty clear on what this patch
does and why.
RFI was committed in r955, so can be used here.
It doesn't make sense to me to #ifdef out code without providing the
equivalent code path for ppc64, so this new code path does belong here
(remember you agreed that having two parallel code paths was
supposedly the only way for migration?).
If you're referring to the suggested use of a .macro, please discuss
this with Blue in general and not some hundred lines down a patch
without referring to the commit message where this is discussed. Blue
has been asking me to turn preprocessor macros into C inline functions
- this construct here seems the closest equivalent in assembler code
and the advantages I see are detailed in the commit message. You have
not yet voiced any particular reason to make this a preprocessor
macro, other than your personal preference for preprocessor macros,
which appears to conflict with Blue's dislike of preprocessor macros
and my dislike of unnecessary multi-line preprocessor macros.
Andreas
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