Re: [PATCH] powerpc/64s: relocation, register save fixes for system reset interrupt
From: Balbir Singh <bsingharora@gmail.com>
Date: 2016-10-13 11:54:33
On 13/10/16 13:17, 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).
Agreed, that is a good side, we also save the PPR in r9 and set the PPR to HMT_MEDIUM
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.
Yep, a much required fixup. I had done a version before your changes
quoted hunk ↗ jump to hunk
Cc: Balbir Singh <bsingharora@gmail.com> Cc: Shreyas B. Prabhu <redacted> Cc: Gautham R. Shenoy <redacted> Signed-off-by: Nicholas Piggin <npiggin@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) \
I wonder if it is a good idea to trap .if (reg == 13); .error "Don't use r13"; .abort; .endif;
quoted hunk ↗ jump to hunk
+ 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 \
Acked-by: Balbir Singh <bsingharora@gmail.com>