[v4,0/1] CPUCFG emulation on older Loongson64 cores

Message

WANG Xuerui May 23, 2020, 1:37 p.m. UTC

This patch brings the CPUCFG instruction to older Loongson64 cores,
enabling a unified way to query processor characteristics on Loongson64
systems. Previous question of how to best integrate machtype-specific
and machtype-agnostic cpu probe logic is resolved. (thanks Thomas for
reviewing!)

Tested on Loongson-3A3000.

Also, to aid userspace in determining CPUCFG availability without having
to handle SIGILL or parse /proc/cpuinfo, a new HWCAP flag is to be added
in a later patch. I am waiting for consensus before implementing this,
as it would be part of userspace ABI.

v4:
- Fixed line wrapping as suggested by Huacai

v3:
- Fixed build on !CONFIG_MACH_LOONGSON64
- Refactored to minimize intrusion to machtype-agnostic cpu probe logic
- Minor tweaks to comment and Kconfig wording
- Dropped Reviewed-by and Tested-by from Jiaxun as the code is
  refactored significantly

v2:
- Fixed one more typo in loongson_regs.h
- Merged simulate_loongson3_csr and simulate_loongson3_csr_cpucfg into
  one (simulate_loongson3_cpucfg), per Huacai's suggestion

WANG Xuerui (1):
  MIPS: emulate CPUCFG instruction on older Loongson64 cores

 arch/mips/Kconfig                             |  12 +
 arch/mips/include/asm/cpu-info.h              |   9 +
 .../include/asm/mach-loongson64/cpucfg-emul.h |  63 +++++
 arch/mips/kernel/cpu-probe.c                  |   9 +
 arch/mips/kernel/traps.c                      |  45 ++++
 arch/mips/loongson64/Makefile                 |   1 +
 arch/mips/loongson64/cpucfg-emul.c            | 217 ++++++++++++++++++
 7 files changed, 356 insertions(+)
 create mode 100644 arch/mips/include/asm/mach-loongson64/cpucfg-emul.h
 create mode 100644 arch/mips/loongson64/cpucfg-emul.c