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-rw-r--r--arch/powerpc/kernel/exceptions-64s.S134
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)