diff options
| author | Nicholas Piggin | 2021-02-08 16:33:26 +1000 |
|---|---|---|
| committer | Michael Ellerman | 2021-02-11 23:35:05 +1100 |
| commit | 14ad0e7d04f46865775fb010ccd96fb1cc83433a (patch) | |
| tree | 4aaad2027fef12ad5ce7dc04c765a8365e6134bf /arch/powerpc | |
| parent | 60a707d0c99aff4eadb7fd334c5fd21df386723e (diff) | |
powerpc/64s: syscall real mode entry use mtmsrd rather than rfid
Have the real mode system call entry handler branch to the kernel
0xc000... address and then use mtmsrd to enable the MMU, rather than use
SRRs and rfid.
Commit 8729c26e675c ("powerpc/64s/exception: Move real to virt switch
into the common handler") implemented this style of real mode entry for
other interrupt handlers, so this brings system calls into line with
them, which is the main motivcation for the change.
This tends to be slightly faster due to avoiding the mtsprs, and it also
does not clobber the SRR registers, which becomes important in a
subsequent change. The real mode entry points don't tend to be too
important for performance these days, but it is possible for a
hypervisor to run guests in AIL=0 mode for certian reasons.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210208063326.331502-1-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 6 | ||||
| -rw-r--r-- | arch/powerpc/kernel/exceptions-64s.S | 9 |
2 files changed, 9 insertions, 6 deletions
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index aa1af139d947..4b2d2823c7a5 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -226,6 +226,12 @@ _ASM_NOKPROBE_SYMBOL(system_call_vectored_emulate) #endif .balign IFETCH_ALIGN_BYTES + .globl system_call_common_real +system_call_common_real: + ld r10,PACAKMSR(r13) /* get MSR value for kernel */ + mtmsrd r10 + + .balign IFETCH_ALIGN_BYTES .globl system_call_common system_call_common: _ASM_NOKPROBE_SYMBOL(system_call_common) diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index c51c436d5845..de3e335bd931 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -1973,12 +1973,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_REAL_LE) HMT_MEDIUM .if ! \virt - __LOAD_HANDLER(r10, system_call_common) - mtspr SPRN_SRR0,r10 - ld r10,PACAKMSR(r13) - mtspr SPRN_SRR1,r10 - RFI_TO_KERNEL - b . /* prevent speculative execution */ + __LOAD_HANDLER(r10, system_call_common_real) + mtctr r10 + bctr .else li r10,MSR_RI mtmsrd r10,1 /* Set RI (EE=0) */ |