On 06/09/2017 20:21, Paul Burton wrote:
> Many architectural features have over time moved from being optional to
> either be required or removed by newer architecture releases. This means
> that in many cases we can know at compile time whether a feature will be
> supported or not purely due to the knowledge we have about the ISA the
> kernel build is targeting.
>
> This patch introduces a bunch of utility macros for checking for
> supported options, ASEs & combinations of those with ISA revisions. It
> then makes use of these in the default definitions of cpu_has_* macros.
> The result is that many of the macros become compile-time constant,
> allowing more optimisation opportunities for the compiler - particularly
> with kernels built for later ISA revisions.
>
> To demonstrate the effect of this patch, the following table shows the
> size in bytes of the kernel binary as reported by scripts/bloat-o-meter
> for v4.12-rc4 maltasmvp_defconfig kernels with & without this patch. A
> variant of maltasmvp_defconfig with CONFIG_CPU_MIPS32_R6 selected is
> also shown, to demonstrate that MIPSr6 systems benefit more due to extra
> features becoming required by that architecture revision. Builds of
> pistachio_defconfig are also shown, as although this is a MIPSr2
> platform it doesn't hardcode any features in a machine-specific
> cpu-feature-overrides.h, which allows it to gain more from this patch
> than the equivalent Malta r2 build.
>
> Config | Before | After | Change
> ----------------|---------|---------|---------
> maltasmvp | 7248316 | 7247714 | -602
> maltasmvp + r6 | 6955595 | 6950777 | -4818
> pistachio | 8650977 | 8363898 | -287079
>
> Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
> Cc: linux-mips@xxxxxxxxxxxxxx
> ---
>
> arch/mips/include/asm/cpu-features.h | 164 +++++++++++++++++++++--------------
> 1 file changed, 101 insertions(+), 63 deletions(-)
>
> diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h
> index 494d38274142..46c669e370d3 100644
> --- a/arch/mips/include/asm/cpu-features.h
> +++ b/arch/mips/include/asm/cpu-features.h
> @@ -13,39 +13,77 @@
> #include <asm/cpu-info.h>
> #include <cpu-feature-overrides.h>
>
> +#define __ase(ase) (cpu_data[0].ases & (ase))
> +#define __opt(opt) (cpu_data[0].options & (opt))
> +
> +/*
> + * Check if __mips_isa_rev is >= isa *and* an option or ASE is detected during
> + * boot (typically by cpu_probe()).
> + *
> + * Note that these should only be used in cases where a kernel built for an
> + * older ISA *cannot* run on a CPU which supports the feature in question. For
> + * example this may be used for features introduced with MIPSr6, since a kernel
> + * built for an older ISA cannot run on a MIPSr6 CPU. This should not be used for
> + * MIPSr2 features however, since a MIPSr1 or earlier kernel might run on a
> + * MIPSr2 CPU.
> + */
> +#define __isa_ge_and_ase(isa, ase) ((__mips_isa_rev >= (isa)) && __ase(ase))
> +#define __isa_ge_and_opt(isa, opt) ((__mips_isa_rev >= (isa)) && __opt(opt))
> +
> +/*
> + * Check if __mips_isa_rev is >= isa *or* an option or ASE is detected during
> + * boot (typically by cpu_probe()).
> + *
> + * These are for use with features that are optional up until a particular ISA
> + * revision & then become required.
> + */
> +#define __isa_ge_or_ase(isa, ase) ((__mips_isa_rev >= (isa)) || __ase(ase))
> +#define __isa_ge_or_opt(isa, opt) ((__mips_isa_rev >= (isa)) || __opt(opt))
> +
> +/*
> + * Check if __mips_isa_rev is < isa *and* an option or ASE is detected during
> + * boot (typically by cpu_probe()).
> + *
> + * These are for use with features that are optional up until a particular ISA
> + * revision & are then removed - ie. no longer present in any CPU implementing
> + * the given ISA revision.
> + */
> +#define __isa_lt_and_ase(isa, ase) ((__mips_isa_rev < (isa)) && __ase(ase))
> +#define __isa_lt_and_opt(isa, opt) ((__mips_isa_rev < (isa)) && __opt(opt))
> +
> /*
> * SMP assumption: Options of CPU 0 are a superset of all processors.
> * This is true for all known MIPS systems.
> */
> #ifndef cpu_has_tlb
> -#define cpu_has_tlb (cpu_data[0].options & MIPS_CPU_TLB)
> +#define cpu_has_tlb __opt(MIPS_CPU_TLB)
> #endif
> #ifndef cpu_has_ftlb
> -#define cpu_has_ftlb (cpu_data[0].options & MIPS_CPU_FTLB)
> +#define cpu_has_ftlb __opt(MIPS_CPU_FTLB)
> #endif
> #ifndef cpu_has_tlbinv
> -#define cpu_has_tlbinv (cpu_data[0].options & MIPS_CPU_TLBINV)
> +#define cpu_has_tlbinv __opt(MIPS_CPU_TLBINV)
> #endif
> #ifndef cpu_has_segments
> -#define cpu_has_segments (cpu_data[0].options & MIPS_CPU_SEGMENTS)
> +#define cpu_has_segments __opt(MIPS_CPU_SEGMENTS)
> #endif
> #ifndef cpu_has_eva
> -#define cpu_has_eva (cpu_data[0].options & MIPS_CPU_EVA)
> +#define cpu_has_eva __opt(MIPS_CPU_EVA)
> #endif
> #ifndef cpu_has_htw
> -#define cpu_has_htw (cpu_data[0].options & MIPS_CPU_HTW)
> +#define cpu_has_htw __opt(MIPS_CPU_HTW)
> #endif
> #ifndef cpu_has_ldpte
> -#define cpu_has_ldpte (cpu_data[0].options & MIPS_CPU_LDPTE)
> +#define cpu_has_ldpte __opt(MIPS_CPU_LDPTE)
> #endif
> #ifndef cpu_has_rixiex
> -#define cpu_has_rixiex (cpu_data[0].options & MIPS_CPU_RIXIEX)
> +#define cpu_has_rixiex __isa_ge_or_opt(6, MIPS_CPU_RIXIEX)
> #endif
> #ifndef cpu_has_maar
> -#define cpu_has_maar (cpu_data[0].options & MIPS_CPU_MAAR)
> +#define cpu_has_maar __opt(MIPS_CPU_MAAR)
> #endif
> #ifndef cpu_has_rw_llb
> -#define cpu_has_rw_llb (cpu_data[0].options & MIPS_CPU_RW_LLB)
> +#define cpu_has_rw_llb __isa_ge_or_opt(6, MIPS_CPU_RW_LLB)
> #endif
>
> /*
> @@ -58,18 +96,18 @@
> #define cpu_has_3kex (!cpu_has_4kex)
> #endif
> #ifndef cpu_has_4kex
> -#define cpu_has_4kex (cpu_data[0].options & MIPS_CPU_4KEX)
> +#define cpu_has_4kex __isa_ge_or_opt(1, MIPS_CPU_4KEX)
> #endif
> #ifndef cpu_has_3k_cache
> -#define cpu_has_3k_cache (cpu_data[0].options & MIPS_CPU_3K_CACHE)
> +#define cpu_has_3k_cache __isa_lt_and_opt(1, MIPS_CPU_3K_CACHE)
> #endif
> #define cpu_has_6k_cache 0
> #define cpu_has_8k_cache 0
> #ifndef cpu_has_4k_cache
> -#define cpu_has_4k_cache (cpu_data[0].options & MIPS_CPU_4K_CACHE)
> +#define cpu_has_4k_cache __isa_ge_or_opt(1, MIPS_CPU_4K_CACHE)
> #endif
> #ifndef cpu_has_tx39_cache
> -#define cpu_has_tx39_cache (cpu_data[0].options & MIPS_CPU_TX39_CACHE)
> +#define cpu_has_tx39_cache __opt(MIPS_CPU_TX39_CACHE)
> #endif
> #ifndef cpu_has_octeon_cache
> #define cpu_has_octeon_cache 0
> @@ -82,89 +120,89 @@
> #define raw_cpu_has_fpu cpu_has_fpu
> #endif
> #ifndef cpu_has_32fpr
> -#define cpu_has_32fpr (cpu_data[0].options & MIPS_CPU_32FPR)
> +#define cpu_has_32fpr __isa_ge_or_opt(1, MIPS_CPU_32FPR)
> #endif
> #ifndef cpu_has_counter
> -#define cpu_has_counter (cpu_data[0].options & MIPS_CPU_COUNTER)
> +#define cpu_has_counter __opt(MIPS_CPU_COUNTER)
> #endif
> #ifndef cpu_has_watch
> -#define cpu_has_watch (cpu_data[0].options & MIPS_CPU_WATCH)
> +#define cpu_has_watch __opt(MIPS_CPU_WATCH)
> #endif
> #ifndef cpu_has_divec
> -#define cpu_has_divec (cpu_data[0].options & MIPS_CPU_DIVEC)
> +#define cpu_has_divec __isa_ge_or_opt(1, MIPS_CPU_DIVEC)
> #endif
> #ifndef cpu_has_vce
> -#define cpu_has_vce (cpu_data[0].options & MIPS_CPU_VCE)
> +#define cpu_has_vce __opt(MIPS_CPU_VCE)
> #endif
> #ifndef cpu_has_cache_cdex_p
> -#define cpu_has_cache_cdex_p (cpu_data[0].options & MIPS_CPU_CACHE_CDEX_P)
> +#define cpu_has_cache_cdex_p __opt(MIPS_CPU_CACHE_CDEX_P)
> #endif
> #ifndef cpu_has_cache_cdex_s
> -#define cpu_has_cache_cdex_s (cpu_data[0].options & MIPS_CPU_CACHE_CDEX_S)
> +#define cpu_has_cache_cdex_s __opt(MIPS_CPU_CACHE_CDEX_S)
> #endif
> #ifndef cpu_has_prefetch
> -#define cpu_has_prefetch (cpu_data[0].options & MIPS_CPU_PREFETCH)
> +#define cpu_has_prefetch __isa_ge_or_opt(1, MIPS_CPU_PREFETCH)
> #endif
> #ifndef cpu_has_mcheck
> -#define cpu_has_mcheck (cpu_data[0].options & MIPS_CPU_MCHECK)
> +#define cpu_has_mcheck __isa_ge_or_opt(1, MIPS_CPU_MCHECK)
> #endif
> #ifndef cpu_has_ejtag
> -#define cpu_has_ejtag (cpu_data[0].options & MIPS_CPU_EJTAG)
> +#define cpu_has_ejtag __opt(MIPS_CPU_EJTAG)
> #endif
> #ifndef cpu_has_llsc
> -#define cpu_has_llsc (cpu_data[0].options & MIPS_CPU_LLSC)
> +#define cpu_has_llsc __isa_ge_or_opt(1, MIPS_CPU_LLSC)
> #endif
> #ifndef cpu_has_bp_ghist
> -#define cpu_has_bp_ghist (cpu_data[0].options & MIPS_CPU_BP_GHIST)
> +#define cpu_has_bp_ghist __opt(MIPS_CPU_BP_GHIST)
> #endif
> #ifndef kernel_uses_llsc
> #define kernel_uses_llsc cpu_has_llsc
> #endif
> #ifndef cpu_has_guestctl0ext
> -#define cpu_has_guestctl0ext (cpu_data[0].options & MIPS_CPU_GUESTCTL0EXT)
> +#define cpu_has_guestctl0ext __opt(MIPS_CPU_GUESTCTL0EXT)
> #endif
> #ifndef cpu_has_guestctl1
> -#define cpu_has_guestctl1 (cpu_data[0].options & MIPS_CPU_GUESTCTL1)
> +#define cpu_has_guestctl1 __opt(MIPS_CPU_GUESTCTL1)
> #endif
> #ifndef cpu_has_guestctl2
> -#define cpu_has_guestctl2 (cpu_data[0].options & MIPS_CPU_GUESTCTL2)
> +#define cpu_has_guestctl2 __opt(MIPS_CPU_GUESTCTL2)
> #endif
> #ifndef cpu_has_guestid
> -#define cpu_has_guestid (cpu_data[0].options & MIPS_CPU_GUESTID)
> +#define cpu_has_guestid __opt(MIPS_CPU_GUESTID)
> #endif
> #ifndef cpu_has_drg
> -#define cpu_has_drg (cpu_data[0].options & MIPS_CPU_DRG)
> +#define cpu_has_drg __opt(MIPS_CPU_DRG)
> #endif
> #ifndef cpu_has_mips16
> -#define cpu_has_mips16 (cpu_data[0].ases & MIPS_ASE_MIPS16)
> +#define cpu_has_mips16 __isa_lt_and_ase(6, MIPS_ASE_MIPS16)
> #endif
> #ifndef cpu_has_mdmx
> -#define cpu_has_mdmx (cpu_data[0].ases & MIPS_ASE_MDMX)
> +#define cpu_has_mdmx __isa_lt_and_ase(6, MIPS_ASE_MDMX)
> #endif
> #ifndef cpu_has_mips3d
> -#define cpu_has_mips3d (cpu_data[0].ases & MIPS_ASE_MIPS3D)
> +#define cpu_has_mips3d __isa_lt_and_ase(6, MIPS_ASE_MIPS3D)
> #endif
> #ifndef cpu_has_smartmips
> -#define cpu_has_smartmips (cpu_data[0].ases & MIPS_ASE_SMARTMIPS)
> +#define cpu_has_smartmips __isa_lt_and_ase(6, MIPS_ASE_SMARTMIPS)
> #endif
>
> #ifndef cpu_has_rixi
> -#define cpu_has_rixi (cpu_data[0].options & MIPS_CPU_RIXI)
> +#define cpu_has_rixi __isa_ge_or_opt(6, MIPS_CPU_RIXI)
> #endif
>
> #ifndef cpu_has_mmips
> # ifdef CONFIG_SYS_SUPPORTS_MICROMIPS
> -# define cpu_has_mmips (cpu_data[0].options & MIPS_CPU_MICROMIPS)
> +# define cpu_has_mmips __opt(MIPS_CPU_MICROMIPS)
> # else
> # define cpu_has_mmips 0
> # endif
> #endif
>
> #ifndef cpu_has_lpa
> -#define cpu_has_lpa (cpu_data[0].options & MIPS_CPU_LPA)
> +#define cpu_has_lpa __opt(MIPS_CPU_LPA)
> #endif
> #ifndef cpu_has_mvh
> -#define cpu_has_mvh (cpu_data[0].options & MIPS_CPU_MVH)
> +#define cpu_has_mvh __opt(MIPS_CPU_MVH)
> #endif
> #ifndef cpu_has_xpa
> #define cpu_has_xpa (cpu_has_lpa && cpu_has_mvh)
> @@ -334,32 +372,32 @@
> #endif
>
> #ifndef cpu_has_dsp
> -#define cpu_has_dsp (cpu_data[0].ases & MIPS_ASE_DSP)
> +#define cpu_has_dsp __ase(MIPS_ASE_DSP)
> #endif
>
> #ifndef cpu_has_dsp2
> -#define cpu_has_dsp2 (cpu_data[0].ases & MIPS_ASE_DSP2P)
> +#define cpu_has_dsp2 __ase(MIPS_ASE_DSP2P)
> #endif
>
> #ifndef cpu_has_dsp3
> -#define cpu_has_dsp3 (cpu_data[0].ases & MIPS_ASE_DSP3)
> +#define cpu_has_dsp3 __ase(MIPS_ASE_DSP3)
> #endif
>
> #ifndef cpu_has_mipsmt
> -#define cpu_has_mipsmt (cpu_data[0].ases & MIPS_ASE_MIPSMT)
> +#define cpu_has_mipsmt __isa_lt_and_ase(6, MIPS_ASE_MIPSMT)
> #endif
>
> #ifndef cpu_has_vp
> -#define cpu_has_vp (cpu_data[0].options & MIPS_CPU_VP)
> +#define cpu_has_vp __isa_ge_and_opt(6, MIPS_CPU_VP)
> #endif
>
> #ifndef cpu_has_userlocal
> -#define cpu_has_userlocal (cpu_data[0].options & MIPS_CPU_ULRI)
> +#define cpu_has_userlocal __isa_ge_or_opt(6, MIPS_CPU_ULRI)
> #endif
>
> #ifdef CONFIG_32BIT
> # ifndef cpu_has_nofpuex
> -# define cpu_has_nofpuex (cpu_data[0].options & MIPS_CPU_NOFPUEX)
> +# define cpu_has_nofpuex __isa_lt_and_opt(1, MIPS_CPU_NOFPUEX)
> # endif
> # ifndef cpu_has_64bits
> # define cpu_has_64bits (cpu_data[0].isa_level & MIPS_CPU_ISA_64BIT)
> @@ -401,19 +439,19 @@
> #endif
>
> #if defined(CONFIG_CPU_MIPSR2_IRQ_VI) && !defined(cpu_has_vint)
> -# define cpu_has_vint (cpu_data[0].options & MIPS_CPU_VINT)
> +# define cpu_has_vint __opt(MIPS_CPU_VINT)
> #elif !defined(cpu_has_vint)
> # define cpu_has_vint 0
> #endif
>
> #if defined(CONFIG_CPU_MIPSR2_IRQ_EI) && !defined(cpu_has_veic)
> -# define cpu_has_veic (cpu_data[0].options & MIPS_CPU_VEIC)
> +# define cpu_has_veic __opt(MIPS_CPU_VEIC)
> #elif !defined(cpu_has_veic)
> # define cpu_has_veic 0
> #endif
>
> #ifndef cpu_has_inclusive_pcaches
> -#define cpu_has_inclusive_pcaches (cpu_data[0].options & MIPS_CPU_INCLUSIVE_CACHES)
> +#define cpu_has_inclusive_pcaches __opt(MIPS_CPU_INCLUSIVE_CACHES)
> #endif
>
> #ifndef cpu_dcache_line_size
> @@ -431,60 +469,60 @@
> #endif
>
> #ifndef cpu_has_perf_cntr_intr_bit
> -#define cpu_has_perf_cntr_intr_bit (cpu_data[0].options & MIPS_CPU_PCI)
> +#define cpu_has_perf_cntr_intr_bit __opt(MIPS_CPU_PCI)
> #endif
>
> #ifndef cpu_has_vz
> -#define cpu_has_vz (cpu_data[0].ases & MIPS_ASE_VZ)
> +#define cpu_has_vz __ase(MIPS_ASE_VZ)
> #endif
>
> #if defined(CONFIG_CPU_HAS_MSA) && !defined(cpu_has_msa)
> -# define cpu_has_msa (cpu_data[0].ases & MIPS_ASE_MSA)
> +# define cpu_has_msa __ase(MIPS_ASE_MSA)
> #elif !defined(cpu_has_msa)
> # define cpu_has_msa 0
> #endif
>
> #ifndef cpu_has_ufr
> -# define cpu_has_ufr (cpu_data[0].options & MIPS_CPU_UFR)
> +# define cpu_has_ufr __opt(MIPS_CPU_UFR)
> #endif
>
> #ifndef cpu_has_fre
> -# define cpu_has_fre (cpu_data[0].options & MIPS_CPU_FRE)
> +# define cpu_has_fre __opt(MIPS_CPU_FRE)
> #endif
>
> #ifndef cpu_has_cdmm
> -# define cpu_has_cdmm (cpu_data[0].options & MIPS_CPU_CDMM)
> +# define cpu_has_cdmm __opt(MIPS_CPU_CDMM)
> #endif
>
> #ifndef cpu_has_small_pages
> -# define cpu_has_small_pages (cpu_data[0].options & MIPS_CPU_SP)
> +# define cpu_has_small_pages __opt(MIPS_CPU_SP)
> #endif
>
> #ifndef cpu_has_nan_legacy
> -#define cpu_has_nan_legacy (cpu_data[0].options & MIPS_CPU_NAN_LEGACY)
> +#define cpu_has_nan_legacy __isa_lt_and_opt(6, MIPS_CPU_NAN_LEGACY)
> #endif
> #ifndef cpu_has_nan_2008
> -#define cpu_has_nan_2008 (cpu_data[0].options & MIPS_CPU_NAN_2008)
> +#define cpu_has_nan_2008 __isa_ge_or_opt(6, MIPS_CPU_NAN_2008)
> #endif
>
> #ifndef cpu_has_ebase_wg
> -# define cpu_has_ebase_wg (cpu_data[0].options & MIPS_CPU_EBASE_WG)
> +# define cpu_has_ebase_wg __opt(MIPS_CPU_EBASE_WG)
> #endif
>
> #ifndef cpu_has_badinstr
> -# define cpu_has_badinstr (cpu_data[0].options & MIPS_CPU_BADINSTR)
> +# define cpu_has_badinstr __isa_ge_or_opt(6, MIPS_CPU_BADINSTR)
> #endif
>
> #ifndef cpu_has_badinstrp
> -# define cpu_has_badinstrp (cpu_data[0].options & MIPS_CPU_BADINSTRP)
> +# define cpu_has_badinstrp __isa_ge_or_opt(6, MIPS_CPU_BADINSTRP)
> #endif
>
> #ifndef cpu_has_contextconfig
> -# define cpu_has_contextconfig (cpu_data[0].options & MIPS_CPU_CTXTC)
> +# define cpu_has_contextconfig __opt(MIPS_CPU_CTXTC)
> #endif
>
> #ifndef cpu_has_perf
> -# define cpu_has_perf (cpu_data[0].options & MIPS_CPU_PERF)
> +# define cpu_has_perf __opt(MIPS_CPU_PERF)
> #endif
>
> /*
Getting a build error for a kernel for an SGI machine with this patch:
In file included from ./arch/mips/include/asm/bitops.h:21:0,
from ./include/linux/bitops.h:36,
from ./include/linux/kernel.h:10,
from arch/mips/kernel/cpu-probe.c:15:
arch/mips/kernel/cpu-probe.c: In function 'cpu_set_nan_2008':
./arch/mips/include/asm/cpu-features.h:52:38: error: '__mips_isa_rev'
undeclared (first use in this function); did you mean '__mips_set_bit'?
#define __isa_lt_and_opt(isa, opt) ((__mips_isa_rev < (isa)) && __opt(opt))
^
My guess is the older platforms don't define __mips_isa_rev anywhere. A lot of
other uses first use 'defined()' to check for its presence, but in this case,
it's being used to setup the '__isa_ge_and_ase' and '__isa_ge_and_opt' macros.
Not sure of a clean workaround to test this patch at the moment. Also am not
seeing where this macro is even defined. Is it a compiler intrinsic?
--
Joshua Kinard
Gentoo/MIPS
kumba@xxxxxxxxxx
6144R/F5C6C943 2015-04-27
177C 1972 1FB8 F254 BAD0 3E72 5C63 F4E3 F5C6 C943
"The past tempts us, the present confuses us, the future frightens us. And our
lives slip away, moment by moment, lost in that vast, terrible in-between."
--Emperor Turhan, Centauri Republic
