powerpc: Make it possible to move the interrupt handlers away from the kernel
This changes the way that the exception prologs transfer control to
the handlers in 64-bit kernels with the aim of making it possible to
have the prologs separate from the main body of the kernel. Now,
instead of computing the address of the handler by taking the top
32 bits of the paca address (to get the 0xc0000000........ part) and
ORing in something in the bottom 16 bits, we get the base address of
the kernel by doing a load from the paca and add an offset.
This also replaces an mfmsr and an ori to compute the MSR value for
the handler with a load from the paca. That makes it unnecessary to
have a separate version of EXCEPTION_PROLOG_PSERIES that forces 64-bit
mode.
We can no longer use a direct branches in the exception prolog code,
which means that the SLB miss handlers can't branch directly to
.slb_miss_realmode any more. Instead we have to compute the address
and do an indirect branch. This is conditional on CONFIG_RELOCATABLE;
for non-relocatable kernels we use a direct branch as before. (A later
change will allow CONFIG_RELOCATABLE to be set on 64-bit powerpc.)
Since the secondary CPUs on pSeries start execution in the first 0x100
bytes of real memory and then have to get to wherever the kernel is,
we can't use a direct branch to get there. Instead this changes
__secondary_hold_spinloop from a flag to a function pointer. When it
is set to a non-NULL value, the secondary CPUs jump to the function
pointed to by that value.
Finally this eliminates one code difference between 32-bit and 64-bit
by making __secondary_hold be the text address of the secondary CPU
spinloop rather than a function descriptor for it.
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/include/asm/exception.h b/arch/powerpc/include/asm/exception.h
index 329148b..d3d4534 100644
--- a/arch/powerpc/include/asm/exception.h
+++ b/arch/powerpc/include/asm/exception.h
@@ -53,14 +53,8 @@
* low halfword of the address, but for Kdump we need the whole low
* word.
*/
-#ifdef CONFIG_CRASH_DUMP
#define LOAD_HANDLER(reg, label) \
- oris reg,reg,(label)@h; /* virt addr of handler ... */ \
- ori reg,reg,(label)@l; /* .. and the rest */
-#else
-#define LOAD_HANDLER(reg, label) \
- ori reg,reg,(label)@l; /* virt addr of handler ... */
-#endif
+ addi reg,reg,(label)-_stext; /* virt addr of handler ... */
#define EXCEPTION_PROLOG_1(area) \
mfspr r13,SPRN_SPRG3; /* get paca address into r13 */ \
@@ -72,37 +66,12 @@
std r9,area+EX_R13(r13); \
mfcr r9
-/*
- * Equal to EXCEPTION_PROLOG_PSERIES, except that it forces 64bit mode.
- * The firmware calls the registered system_reset_fwnmi and
- * machine_check_fwnmi handlers in 32bit mode if the cpu happens to run
- * a 32bit application at the time of the event.
- * This firmware bug is present on POWER4 and JS20.
- */
-#define EXCEPTION_PROLOG_PSERIES_FORCE_64BIT(area, label) \
- EXCEPTION_PROLOG_1(area); \
- clrrdi r12,r13,32; /* get high part of &label */ \
- mfmsr r10; \
- /* force 64bit mode */ \
- li r11,5; /* MSR_SF_LG|MSR_ISF_LG */ \
- rldimi r10,r11,61,0; /* insert into top 3 bits */ \
- /* done 64bit mode */ \
- mfspr r11,SPRN_SRR0; /* save SRR0 */ \
- LOAD_HANDLER(r12,label) \
- ori r10,r10,MSR_IR|MSR_DR|MSR_RI; \
- mtspr SPRN_SRR0,r12; \
- mfspr r12,SPRN_SRR1; /* and SRR1 */ \
- mtspr SPRN_SRR1,r10; \
- rfid; \
- b . /* prevent speculative execution */
-
#define EXCEPTION_PROLOG_PSERIES(area, label) \
EXCEPTION_PROLOG_1(area); \
- clrrdi r12,r13,32; /* get high part of &label */ \
- mfmsr r10; \
+ ld r12,PACAKBASE(r13); /* get high part of &label */ \
+ ld r10,PACAKMSR(r13); /* get MSR value for kernel */ \
mfspr r11,SPRN_SRR0; /* save SRR0 */ \
LOAD_HANDLER(r12,label) \
- ori r10,r10,MSR_IR|MSR_DR|MSR_RI; \
mtspr SPRN_SRR0,r12; \
mfspr r12,SPRN_SRR1; /* and SRR1 */ \
mtspr SPRN_SRR1,r10; \
@@ -210,11 +179,10 @@
std r10,PACA_EXGEN+EX_R13(r13); \
std r11,PACA_EXGEN+EX_R11(r13); \
std r12,PACA_EXGEN+EX_R12(r13); \
- clrrdi r12,r13,32; /* get high part of &label */ \
- mfmsr r10; \
+ ld r12,PACAKBASE(r13); /* get high part of &label */ \
+ ld r10,PACAKMSR(r13); /* get MSR value for kernel */ \
mfspr r11,SPRN_SRR0; /* save SRR0 */ \
LOAD_HANDLER(r12,label##_common) \
- ori r10,r10,MSR_IR|MSR_DR|MSR_RI; \
mtspr SPRN_SRR0,r12; \
mfspr r12,SPRN_SRR1; /* and SRR1 */ \
mtspr SPRN_SRR1,r10; \