diff options
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/kernel/exceptions-64s.S | 134 |
1 files changed, 97 insertions, 37 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index ae418b85c17c..2f700a15bfa3 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -821,46 +821,80 @@ EXC_VIRT(trap_0b, 0x4b00, 0x100, 0xb00) TRAMP_KVM(PACA_EXGEN, 0xb00) EXC_COMMON(trap_0b_common, 0xb00, unknown_exception) +/* + * system call / hypercall (0xc00, 0x4c00) + * + * The system call exception is invoked with "sc 0" and does not alter HV bit. + * There is support for kernel code to invoke system calls but there are no + * in-tree users. + * + * The hypercall is invoked with "sc 1" and sets HV=1. + * + * In HPT, sc 1 always goes to 0xc00 real mode. In RADIX, sc 1 can go to + * 0x4c00 virtual mode. + * + * Call convention: + * + * syscall register convention is in Documentation/powerpc/syscall64-abi.txt + * + * For hypercalls, the register convention is as follows: + * r0 volatile + * r1-2 nonvolatile + * r3 volatile parameter and return value for status + * r4-r10 volatile input and output value + * r11 volatile hypercall number and output value + * r12 volatile + * r13-r31 nonvolatile + * LR nonvolatile + * CTR volatile + * XER volatile + * CR0-1 CR5-7 volatile + * CR2-4 nonvolatile + * 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. + */ #ifdef CONFIG_KVM_BOOK3S_64_HANDLER - /* - * If CONFIG_KVM_BOOK3S_64_HANDLER is set, save the PPR (on systems - * that support it) before changing to HMT_MEDIUM. That allows the KVM - * code to save that value into the guest state (it is the guest's PPR - * value). Otherwise just change to HMT_MEDIUM as userspace has - * already saved the PPR. - */ + /* + * 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. + * + * Userspace syscalls have already saved the PPR, hcalls must save + * it before setting HMT_MEDIUM. + */ #define SYSCALL_KVMTEST \ - SET_SCRATCH0(r13); \ + mr r12,r13; \ GET_PACA(r13); \ - std r9,PACA_EXGEN+EX_R9(r13); \ - OPT_GET_SPR(r9, SPRN_PPR, CPU_FTR_HAS_PPR); \ + mtctr r10; \ + KVMTEST_PR(0xc00); /* uses r10, branch to do_kvm_0xc00_system_call */ \ HMT_MEDIUM; \ - std r10,PACA_EXGEN+EX_R10(r13); \ - OPT_SAVE_REG_TO_PACA(PACA_EXGEN+EX_PPR, r9, CPU_FTR_HAS_PPR); \ - mfcr r9; \ - KVMTEST_PR(0xc00); \ - GET_SCRATCH0(r13) + mr r9,r12; \ #else #define SYSCALL_KVMTEST \ - HMT_MEDIUM + HMT_MEDIUM; \ + mr r9,r13; \ + GET_PACA(r13); #endif #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 \ +#define SYSCALL_FASTENDIAN_TEST \ BEGIN_FTR_SECTION \ cmpdi r0,0x1ebe ; \ beq- 1f ; \ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) \ - mr r9,r13 ; \ - GET_PACA(r13) ; \ - mfspr r11,SPRN_SRR0 ; \ -0: -#define SYSCALL_PSERIES_2_RFID \ +/* + * After SYSCALL_KVMTEST, we reach here with PACA in r13, r13 in r9, + * and HMT_MEDIUM. + */ +#define SYSCALL_REAL \ + mfspr r11,SPRN_SRR0 ; \ mfspr r12,SPRN_SRR1 ; \ LOAD_SYSCALL_HANDLER(r10) ; \ mtspr SPRN_SRR0,r10 ; \ @@ -869,11 +903,12 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) \ rfid ; \ b . ; /* prevent speculative execution */ -#define SYSCALL_PSERIES_3 \ +#define SYSCALL_FASTENDIAN \ /* Fast LE/BE switch system call */ \ 1: mfspr r12,SPRN_SRR1 ; \ xori r12,r12,MSR_LE ; \ mtspr SPRN_SRR1,r12 ; \ + mr r13,r9 ; \ rfid ; /* return to userspace */ \ b . ; /* prevent speculative execution */ @@ -882,16 +917,18 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) \ * We can't branch directly so we do it via the CTR which * is volatile across system calls. */ -#define SYSCALL_PSERIES_2_DIRECT \ - LOAD_SYSCALL_HANDLER(r12) ; \ - mtctr r12 ; \ +#define SYSCALL_VIRT \ + LOAD_SYSCALL_HANDLER(r10) ; \ + mtctr r10 ; \ + mfspr r11,SPRN_SRR0 ; \ mfspr r12,SPRN_SRR1 ; \ li r10,MSR_RI ; \ mtmsrd r10,1 ; \ bctr ; #else /* We can branch directly */ -#define SYSCALL_PSERIES_2_DIRECT \ +#define SYSCALL_VIRT \ + mfspr r11,SPRN_SRR0 ; \ mfspr r12,SPRN_SRR1 ; \ li r10,MSR_RI ; \ mtmsrd r10,1 ; /* Set RI (EE=0) */ \ @@ -899,20 +936,43 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) \ #endif EXC_REAL_BEGIN(system_call, 0xc00, 0x100) - SYSCALL_KVMTEST - SYSCALL_PSERIES_1 - SYSCALL_PSERIES_2_RFID - SYSCALL_PSERIES_3 + SYSCALL_KVMTEST /* loads PACA into r13, and saves r13 to r9 */ + SYSCALL_FASTENDIAN_TEST + SYSCALL_REAL + SYSCALL_FASTENDIAN EXC_REAL_END(system_call, 0xc00, 0x100) EXC_VIRT_BEGIN(system_call, 0x4c00, 0x100) - SYSCALL_KVMTEST - SYSCALL_PSERIES_1 - SYSCALL_PSERIES_2_DIRECT - SYSCALL_PSERIES_3 + SYSCALL_KVMTEST /* loads PACA into r13, and saves r13 to r9 */ + SYSCALL_FASTENDIAN_TEST + SYSCALL_VIRT + SYSCALL_FASTENDIAN EXC_VIRT_END(system_call, 0x4c00, 0x100) -TRAMP_KVM(PACA_EXGEN, 0xc00) +#ifdef CONFIG_KVM_BOOK3S_64_HANDLER + /* + * This is a hcall, so register convention is as above, with these + * differences: + * r13 = PACA + * r12 = orig r13 + * ctr = orig r10 + */ +TRAMP_KVM_BEGIN(do_kvm_0xc00) + /* + * Save the PPR (on systems that support it) before changing to + * 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) + HMT_MEDIUM + OPT_SAVE_REG_TO_PACA(PACA_EXGEN+EX_PPR, r0, CPU_FTR_HAS_PPR) + mfctr r10 + SET_SCRATCH0(r12) + std r9,PACA_EXGEN+EX_R9(r13) + mfcr r9 + std r10,PACA_EXGEN+EX_R10(r13) + KVM_HANDLER(PACA_EXGEN, EXC_STD, 0xc00) +#endif EXC_REAL(single_step, 0xd00, 0x100) |