Hi Nick,
[Updated Shreyas's current e-mail address:
"Shreyas B. Prabhu" <shreya...@gmail.com>]
On Thu, Oct 13, 2016 at 01:17:14PM +1100, Nicholas Piggin wrote:
> This patch does a couple of things. First of all, powernv immediately
> explodes when running a relocated kernel, because the system reset
> exception for handling sleeps does not do correct relocated branches.
>
> Secondly, the sleep handling code trashes the condition and cfar
> registers, which we would like to preserve for debugging purposes (for
> non-sleep case exception).
>
> This patch changes the exception to use the standard format that saves
> registers before any tests or branches are made. It adds the test for
> idle-wakeup as an "extra" to break out of the normal exception path.
> Then it branches to a relocated idle handler that calls the various
> idle handling functions.
>
> After this patch, POWER8 CPU simulator now boots powernv kernel that is
> running at non-zero.
This patch looks good to me. I have tested this on POWER8 and verified
that we are correctly waking up from nap, sleep and winkle.
Acked-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
>
> Cc: Balbir Singh <bsinghar...@gmail.com>
> Cc: Shreyas B. Prabhu <shre...@linux.vnet.ibm.com>
> Cc: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
> ---
> arch/powerpc/include/asm/exception-64s.h | 16 ++++++++++
> arch/powerpc/kernel/exceptions-64s.S | 50
> ++++++++++++++++++--------------
> 2 files changed, 45 insertions(+), 21 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/exception-64s.h
> b/arch/powerpc/include/asm/exception-64s.h
> index 2e4e7d8..84d49b1 100644
> --- a/arch/powerpc/include/asm/exception-64s.h
> +++ b/arch/powerpc/include/asm/exception-64s.h
> @@ -93,6 +93,10 @@
> ld reg,PACAKBASE(r13); /* get high part of &label */ \
> ori reg,reg,(FIXED_SYMBOL_ABS_ADDR(label))@l;
>
> +#define __LOAD_HANDLER(reg, label) \
> + ld reg,PACAKBASE(r13); \
> + ori reg,reg,(ABS_ADDR(label))@l;
> +
> /* Exception register prefixes */
> #define EXC_HV H
> #define EXC_STD
> @@ -208,6 +212,18 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
> #define kvmppc_interrupt kvmppc_interrupt_pr
> #endif
>
> +#ifdef CONFIG_RELOCATABLE
> +#define BRANCH_TO_COMMON(reg, label) \
> + __LOAD_HANDLER(reg, label); \
> + mtctr reg; \
> + bctr
> +
> +#else
> +#define BRANCH_TO_COMMON(reg, label) \
> + b label
> +
> +#endif
> +
> #define __KVM_HANDLER_PROLOG(area, n)
> \
> BEGIN_FTR_SECTION_NESTED(947) \
> ld r10,area+EX_CFAR(r13); \
> diff --git a/arch/powerpc/kernel/exceptions-64s.S
> b/arch/powerpc/kernel/exceptions-64s.S
> index 08992f8..e680e84 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -95,19 +95,35 @@ __start_interrupts:
> /* No virt vectors corresponding with 0x0..0x100 */
> EXC_VIRT_NONE(0x4000, 0x4100)
>
> -EXC_REAL_BEGIN(system_reset, 0x100, 0x200)
> - SET_SCRATCH0(r13)
> +
> #ifdef CONFIG_PPC_P7_NAP
> -BEGIN_FTR_SECTION
> - /* Running native on arch 2.06 or later, check if we are
> - * waking up from nap/sleep/winkle.
> + /*
> + * If running native on arch 2.06 or later, check if we are waking up
> + * from nap/sleep/winkle, and branch to idle handler.
> */
> - mfspr r13,SPRN_SRR1
> - rlwinm. r13,r13,47-31,30,31
> - beq 9f
> +#define IDLETEST(n) \
> + BEGIN_FTR_SECTION ; \
> + mfspr r10,SPRN_SRR1 ; \
> + rlwinm. r10,r10,47-31,30,31 ; \
> + beq- 1f ; \
> + cmpwi cr3,r10,2 ; \
> + BRANCH_TO_COMMON(r10, system_reset_idle_common) ; \
> +1: \
> + END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
> +#else
> +#define IDLETEST NOTEST
> +#endif
>
> - cmpwi cr3,r13,2
> - GET_PACA(r13)
> +EXC_REAL_BEGIN(system_reset, 0x100, 0x200)
> + SET_SCRATCH0(r13)
> + EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, system_reset_common, EXC_STD,
> + IDLETEST, 0x100)
> +
> +EXC_REAL_END(system_reset, 0x100, 0x200)
> +EXC_VIRT_NONE(0x4100, 0x4200)
> +
> +#ifdef CONFIG_PPC_P7_NAP
> +EXC_COMMON_BEGIN(system_reset_idle_common)
> bl pnv_restore_hyp_resource
>
> li r0,PNV_THREAD_RUNNING
> @@ -130,14 +146,8 @@ BEGIN_FTR_SECTION
> blt cr3,2f
> b pnv_wakeup_loss
> 2: b pnv_wakeup_noloss
> +#endif
>
> -9:
> -END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
> -#endif /* CONFIG_PPC_P7_NAP */
> - EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, system_reset_common, EXC_STD,
> - NOTEST, 0x100)
> -EXC_REAL_END(system_reset, 0x100, 0x200)
> -EXC_VIRT_NONE(0x4100, 0x4200)
> EXC_COMMON(system_reset_common, 0x100, system_reset_exception)
>
> #ifdef CONFIG_PPC_PSERIES
> @@ -817,10 +827,8 @@ EXC_VIRT(trap_0b, 0x4b00, 0x4c00, 0xb00)
> TRAMP_KVM(PACA_EXGEN, 0xb00)
> EXC_COMMON(trap_0b_common, 0xb00, unknown_exception)
>
> -
> -#define LOAD_SYSCALL_HANDLER(reg) \
> - ld reg,PACAKBASE(r13); \
> - ori reg,reg,(ABS_ADDR(system_call_common))@l;
> +#define LOAD_SYSCALL_HANDLER(reg) \
> + __LOAD_HANDLER(reg, system_call_common)
>
> /* Syscall routine is used twice, in reloc-off and reloc-on paths */
> #define SYSCALL_PSERIES_1 \
> --
> 2.9.3
>
