diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2020-06-11 18:12:03 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-07-22 23:00:27 +1000 |
| commit | 7fa95f9adaee7e5cbb195d3359741120829e488b (patch) | |
| tree | 1ca2d65102ad2c5223afe9a78e3105836982479f /arch/powerpc/lib | |
| parent | b2dc2977cba48990df45e0a96150663d4f342700 (diff) | |
powerpc/64s: system call support for scv/rfscv instructions
Add support for the scv instruction on POWER9 and later CPUs.
For now this implements the zeroth scv vector 'scv 0', as identical to
'sc' system calls, with the exception that LR is not preserved, nor
are volatile CR registers, and error is not indicated with CR0[SO],
but by returning a negative errno.
rfscv is implemented to return from scv type system calls. It can not
be used to return from sc system calls because those are defined to
preserve LR.
getpid syscall throughput on POWER9 is improved by 26% (428 to 318
cycles), largely due to reducing mtmsr and mtspr.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fix ppc64e build]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200611081203.995112-3-npiggin@gmail.com
Diffstat (limited to 'arch/powerpc/lib')
| -rw-r--r-- | arch/powerpc/lib/sstep.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c index 5abe98216dc2..ab6a137c3862 100644 --- a/arch/powerpc/lib/sstep.c +++ b/arch/powerpc/lib/sstep.c @@ -16,6 +16,7 @@ #include <asm/disassemble.h> extern char system_call_common[]; +extern char system_call_vectored_emulate[]; #ifdef CONFIG_PPC64 /* Bits in SRR1 that are copied from MSR */ @@ -1236,6 +1237,9 @@ int analyse_instr(struct instruction_op *op, const struct pt_regs *regs, case 17: /* sc */ if ((word & 0xfe2) == 2) op->type = SYSCALL; + else if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && + (word & 0xfe3) == 1) + op->type = SYSCALL_VECTORED_0; else op->type = UNKNOWN; return 0; @@ -3378,6 +3382,18 @@ int emulate_step(struct pt_regs *regs, struct ppc_inst instr) regs->msr = MSR_KERNEL; return 1; +#ifdef CONFIG_PPC64_BOOK3S + case SYSCALL_VECTORED_0: /* scv 0 */ + regs->gpr[9] = regs->gpr[13]; + regs->gpr[10] = MSR_KERNEL; + regs->gpr[11] = regs->nip + 4; + regs->gpr[12] = regs->msr & MSR_MASK; + regs->gpr[13] = (unsigned long) get_paca(); + regs->nip = (unsigned long) &system_call_vectored_emulate; + regs->msr = MSR_KERNEL; + return 1; +#endif + case RFI: return -1; #endif |