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| author |   Nicholas Piggin <npiggin@gmail.com> | 2017-01-27 14:00:34 +1000 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2017-01-31 19:07:39 +1100 |
| commit | a97a65d53d9f53b6897dc1b2aed381bc1707136b (patch) | |
| tree | 08dcf2d0b98a978d80bf09dc5f6829e9831c7bb5 /arch/powerpc/include/asm/exception-64s.h | |
| parent | KVM: PPC: Book3S: Move 64-bit KVM interrupt handler out from alt section (diff) | |
| download | linux-dev-a97a65d53d9f53b6897dc1b2aed381bc1707136b.tar.xz linux-dev-a97a65d53d9f53b6897dc1b2aed381bc1707136b.zip | |
KVM: PPC: Book3S: 64-bit CONFIG_RELOCATABLE support for interrupts
64-bit Book3S exception handlers must find the dynamic kernel base
to add to the target address when branching beyond __end_interrupts,
in order to support kernel running at non-0 physical address.
Support this in KVM by branching with CTR, similarly to regular
interrupt handlers. The guest CTR saved in HSTATE_SCRATCH1 and
restored after the branch.
Without this, the host kernel hangs and crashes randomly when it is
running at a non-0 address and a KVM guest is started.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/include/asm/exception-64s.h')
| -rw-r--r-- | arch/powerpc/include/asm/exception-64s.h | 45 |
1 files changed, 41 insertions, 4 deletions
diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h index a02a268bde6b..9a5dbfb2d9f2 100644 --- a/arch/powerpc/include/asm/exception-64s.h +++ b/arch/powerpc/include/asm/exception-64s.h @@ -97,6 +97,15 @@ ld reg,PACAKBASE(r13); \ ori reg,reg,(ABS_ADDR(label))@l; +/* + * Branches from unrelocated code (e.g., interrupts) to labels outside + * head-y require >64K offsets. + */ +#define __LOAD_FAR_HANDLER(reg, label) \ + ld reg,PACAKBASE(r13); \ + ori reg,reg,(ABS_ADDR(label))@l; \ + addis reg,reg,(ABS_ADDR(label))@h; + /* Exception register prefixes */ #define EXC_HV H #define EXC_STD @@ -227,12 +236,40 @@ END_FTR_SECTION_NESTED(ftr,ftr,943) mtctr reg; \ bctr +/* + * KVM requires __LOAD_FAR_HANDLER. + * + * __BRANCH_TO_KVM_EXIT branches are also a special case because they + * explicitly use r9 then reload it from PACA before branching. Hence + * the double-underscore. + */ +#define __BRANCH_TO_KVM_EXIT(area, label) \ + mfctr r9; \ + std r9,HSTATE_SCRATCH1(r13); \ + __LOAD_FAR_HANDLER(r9, label); \ + mtctr r9; \ + ld r9,area+EX_R9(r13); \ + bctr + +#define BRANCH_TO_KVM(reg, label) \ + __LOAD_FAR_HANDLER(reg, label); \ + mtctr reg; \ + bctr + #else #define BRANCH_TO_COMMON(reg, label) \ b label +#define BRANCH_TO_KVM(reg, label) \ + b label + +#define __BRANCH_TO_KVM_EXIT(area, label) \ + ld r9,area+EX_R9(r13); \ + b label + #endif + #define __KVM_HANDLER(area, h, n) \ BEGIN_FTR_SECTION_NESTED(947) \ ld r10,area+EX_CFAR(r13); \ @@ -246,8 +283,8 @@ END_FTR_SECTION_NESTED(ftr,ftr,943) std r12,HSTATE_SCRATCH0(r13); \ sldi r12,r9,32; \ ori r12,r12,(n); \ - ld r9,area+EX_R9(r13); \ - b kvmppc_interrupt + /* This reloads r9 before branching to kvmppc_interrupt */ \ + __BRANCH_TO_KVM_EXIT(area, kvmppc_interrupt) #define __KVM_HANDLER_SKIP(area, h, n) \ cmpwi r10,KVM_GUEST_MODE_SKIP; \ @@ -260,8 +297,8 @@ END_FTR_SECTION_NESTED(ftr,ftr,943) std r12,HSTATE_SCRATCH0(r13); \ sldi r12,r9,32; \ ori r12,r12,(n); \ - ld r9,area+EX_R9(r13); \ - b kvmppc_interrupt; \ + /* This reloads r9 before branching to kvmppc_interrupt */ \ + __BRANCH_TO_KVM_EXIT(area, kvmppc_interrupt); \ 89: mtocrf 0x80,r9; \ ld r9,area+EX_R9(r13); \ ld r10,area+EX_R10(r13); \ |