diff options
Diffstat (limited to 'arch/powerpc/kernel/exceptions-64s.S')
| -rw-r--r-- | arch/powerpc/kernel/exceptions-64s.S | 38 |
1 files changed, 23 insertions, 15 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index e6d8354d79ef..f14f3c04ec7e 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -824,7 +824,7 @@ EXC_COMMON(trap_0b_common, 0xb00, unknown_exception) * r3 volatile parameter and return value for status * r4-r10 volatile input and output value * r11 volatile hypercall number and output value - * r12 volatile + * r12 volatile input and output value * r13-r31 nonvolatile * LR nonvolatile * CTR volatile @@ -834,25 +834,26 @@ EXC_COMMON(trap_0b_common, 0xb00, unknown_exception) * Other registers nonvolatile * * The intersection of volatile registers that don't contain possible - * inputs is: r12, cr0, xer, ctr. We may use these as scratch regs - * upon entry without saving. + * inputs is: cr0, xer, ctr. We may use these as scratch regs upon entry + * without saving, though xer is not a good idea to use, as hardware may + * interpret some bits so it may be costly to change them. */ #ifdef CONFIG_KVM_BOOK3S_64_HANDLER /* * There is a little bit of juggling to get syscall and hcall - * working well. Save r10 in ctr to be restored in case it is a - * hcall. + * working well. Save r13 in ctr to avoid using SPRG scratch + * register. * * Userspace syscalls have already saved the PPR, hcalls must save * it before setting HMT_MEDIUM. */ #define SYSCALL_KVMTEST \ - mr r12,r13; \ + mtctr r13; \ GET_PACA(r13); \ - mtctr r10; \ + std r10,PACA_EXGEN+EX_R10(r13); \ KVMTEST_PR(0xc00); /* uses r10, branch to do_kvm_0xc00_system_call */ \ HMT_MEDIUM; \ - mr r9,r12; \ + mfctr r9; #else #define SYSCALL_KVMTEST \ @@ -935,8 +936,8 @@ EXC_VIRT_END(system_call, 0x4c00, 0x100) * This is a hcall, so register convention is as above, with these * differences: * r13 = PACA - * r12 = orig r13 - * ctr = orig r10 + * ctr = orig r13 + * orig r10 saved in PACA */ TRAMP_KVM_BEGIN(do_kvm_0xc00) /* @@ -944,14 +945,13 @@ TRAMP_KVM_BEGIN(do_kvm_0xc00) * HMT_MEDIUM. That allows the KVM code to save that value into the * guest state (it is the guest's PPR value). */ - OPT_GET_SPR(r0, SPRN_PPR, CPU_FTR_HAS_PPR) + OPT_GET_SPR(r10, SPRN_PPR, CPU_FTR_HAS_PPR) HMT_MEDIUM - OPT_SAVE_REG_TO_PACA(PACA_EXGEN+EX_PPR, r0, CPU_FTR_HAS_PPR) + OPT_SAVE_REG_TO_PACA(PACA_EXGEN+EX_PPR, r10, CPU_FTR_HAS_PPR) mfctr r10 - SET_SCRATCH0(r12) + SET_SCRATCH0(r10) std r9,PACA_EXGEN+EX_R9(r13) mfcr r9 - std r10,PACA_EXGEN+EX_R10(r13) KVM_HANDLER(PACA_EXGEN, EXC_STD, 0xc00) #endif @@ -1325,10 +1325,18 @@ EXC_VIRT_NONE(0x5800, 0x100) std r10,PACA_EXGEN+EX_R13(r13); \ EXCEPTION_PROLOG_PSERIES_1(soft_nmi_common, _H) +/* + * Branch to soft_nmi_interrupt using the emergency stack. The emergency + * stack is one that is usable by maskable interrupts so long as MSR_EE + * remains off. It is used for recovery when something has corrupted the + * normal kernel stack, for example. The "soft NMI" must not use the process + * stack because we want irq disabled sections to avoid touching the stack + * at all (other than PMU interrupts), so use the emergency stack for this, + * and run it entirely with interrupts hard disabled. + */ EXC_COMMON_BEGIN(soft_nmi_common) mr r10,r1 ld r1,PACAEMERGSP(r13) - ld r1,PACA_NMI_EMERG_SP(r13) subi r1,r1,INT_FRAME_SIZE EXCEPTION_COMMON_NORET_STACK(PACA_EXGEN, 0x900, system_reset, soft_nmi_interrupt, |