Messages in this thread | | | Date | Fri, 15 May 2015 13:49:35 -0700 | From | David Daney <> | Subject | Re: [PATCH v2] MIPS64: Support of at least 48 bits of SEGBITS |
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On 05/14/2015 06:34 PM, Leonid Yegoshin wrote: > SEGBITS default is 40 bits or less, depending from CPU type. > This patch introduces 48bits of application virtual address (SEGBITS) support. > It is defined only for 16K and 64K pages and is optional (configurable). > > Penalty - a small number of additional pages for generic (small) applications. > But for 64K pages it adds 3rd level of PTE structure, which has a little > impact during software TLB refill. > > This patch is needed because MIPS I6XXX and P6XXX cores have 48 bit of > virtual address in each segment (SEGBITS). >
Those processors don't require the patch. You wrote the patch to give a larger VA space at the request of kernel users. So perhaps say:
The patch (optionally) increases the VA space available to userspace processes from N-bits to 48-bits
> Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> > --- > V2: Added correction for defintion of TASK_SIZE64 > --- > arch/mips/Kconfig | 11 +++++++++++ > arch/mips/include/asm/pgtable-64.h | 18 +++++++++++------- > arch/mips/include/asm/processor.h | 6 +++++- > 3 files changed, 27 insertions(+), 8 deletions(-) > > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig > index 76efb02ae99f..3acff2f065e9 100644 > --- a/arch/mips/Kconfig > +++ b/arch/mips/Kconfig > @@ -2032,6 +2032,17 @@ config PAGE_SIZE_64KB > > endchoice > > +config 48VMBITS
Should probabaly be called VABITS instead of VMBITS to match the terms used in the architecture reference manuals, as well as other ports (ARM64).
Perhaps MIPS_VA_BITS_48
> + bool "48 bits virtual memory" > + depends on PAGE_SIZE_16KB || PAGE_SIZE_64KB > + depends on 64BIT > + help > + Define a maximum at least 48 bits of application virtual memory. > + Default is 40 bits or less, depending from CPU. > + In generic (small) application it is a small set of pages increase > + in page tables. > + If unsure, say N. > + > config FORCE_MAX_ZONEORDER > int "Maximum zone order" > range 14 64 if MIPS_HUGE_TLB_SUPPORT && PAGE_SIZE_64KB > diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h > index cf661a2fb141..c6b5473440e6 100644 > --- a/arch/mips/include/asm/pgtable-64.h > +++ b/arch/mips/include/asm/pgtable-64.h > @@ -17,7 +17,7 @@ > #include <asm/cachectl.h> > #include <asm/fixmap.h> > > -#ifdef CONFIG_PAGE_SIZE_64KB > +#if defined(CONFIG_PAGE_SIZE_64KB) && !defined(CONFIG_48VMBITS) > #include <asm-generic/pgtable-nopmd.h> > #else > #include <asm-generic/pgtable-nopud.h> > @@ -90,7 +90,11 @@ > #define PTE_ORDER 0 > #endif > #ifdef CONFIG_PAGE_SIZE_16KB > -#define PGD_ORDER 0 > +#ifdef CONFIG_48VMBITS > +#define PGD_ORDER 1 > +#else > +#define PGD_ORDER 0 > +#endif > #define PUD_ORDER aieeee_attempt_to_allocate_pud > #define PMD_ORDER 0 > #define PTE_ORDER 0 > @@ -104,7 +108,11 @@ > #ifdef CONFIG_PAGE_SIZE_64KB > #define PGD_ORDER 0 > #define PUD_ORDER aieeee_attempt_to_allocate_pud > +#ifdef CONFIG_48VMBITS > +#define PMD_ORDER 0 > +#else > #define PMD_ORDER aieeee_attempt_to_allocate_pmd > +#endif > #define PTE_ORDER 0 > #endif > > @@ -114,11 +122,7 @@ > #endif > #define PTRS_PER_PTE ((PAGE_SIZE << PTE_ORDER) / sizeof(pte_t)) > > -#if PGDIR_SIZE >= TASK_SIZE64 > -#define USER_PTRS_PER_PGD (1) > -#else > -#define USER_PTRS_PER_PGD (TASK_SIZE64 / PGDIR_SIZE) > -#endif > +#define USER_PTRS_PER_PGD ((TASK_SIZE64 / PGDIR_SIZE)?(TASK_SIZE64 / PGDIR_SIZE):1) > #define FIRST_USER_ADDRESS 0UL > > /* > diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h > index 9b3b48e21c22..bd2030f32ea4 100644 > --- a/arch/mips/include/asm/processor.h > +++ b/arch/mips/include/asm/processor.h > @@ -69,7 +69,11 @@ extern unsigned int vced_count, vcei_count; > * 8192EB ... > */ > #define TASK_SIZE32 0x7fff8000UL > -#define TASK_SIZE64 0x10000000000UL > +#ifdef CONFIG_48VMBITS > +#define TASK_SIZE64 (0x1UL << ((cpu_data[0].vmbits>48)?48:cpu_data[0].vmbits)) > +#else > +#define TASK_SIZE64 (0x10000000000UL) > +#endif > #define TASK_SIZE (test_thread_flag(TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE64) > #define STACK_TOP_MAX TASK_SIZE64 > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > >
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