On Thu, Sep 11, 2008 at 01:53:06AM +0400, Ilya Yanok wrote:
> This patch adds support for page sizes bigger than 4KB (16KB/64KB/256KB) on
> PPC 44x.
[snip]
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 587da5e..ca93157 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -413,6 +413,29 @@ config PPC_64K_PAGES
> while on hardware with such support, it will be used to map
> normal application pages.
>
> +choice
> + prompt "Page size"
> + depends on 44x && PPC32
> + default PPC32_4K_PAGES
> + help
> + The PAGE_SIZE definition. Increasing the page size may
> + improve the system performance in some dedicated cases.
> + If unsure, set it to 4 KB.
> +
> +config PPC32_4K_PAGES
> + bool "4k page size"
> +
> +config PPC32_16K_PAGES
> + bool "16k page size"
> +
> +config PPC32_64K_PAGES
> + bool "64k page size"
> +
> +config PPC32_256K_PAGES
> + bool "256k page size"
> +
I don't see any reason to have a separate set of config options for 32
and 64-bit. Just make the once choice, but only have the individual
pagesize options enabled on machines that support them.
[snip]
> index e088545..1de90b4 100644
> --- a/arch/powerpc/include/asm/page.h
> +++ b/arch/powerpc/include/asm/page.h
> @@ -15,12 +15,17 @@
> #include <asm/types.h>
>
> /*
> - * On PPC32 page size is 4K. For PPC64 we support either 4K or 64K software
> + * On regular PPC32 page size is 4K (but we support 4K/16K/64K/256K pages
> + * on PPC44x). For PPC64 we support either 4K or 64K software
> * page size. When using 64K pages however, whether we are really supporting
> * 64K pages in HW or not is irrelevant to those definitions.
> */
> -#ifdef CONFIG_PPC_64K_PAGES
> +#if defined(CONFIG_PPC32_256K_PAGES)
> +#define PAGE_SHIFT 18
> +#elif defined(CONFIG_PPC32_64K_PAGES) || defined(CONFIG_PPC_64K_PAGES)
> #define PAGE_SHIFT 16
> +#elif defined(CONFIG_PPC32_16K_PAGES)
> +#define PAGE_SHIFT 14
> #else
> #define PAGE_SHIFT 12
> #endif
> @@ -140,11 +145,19 @@ typedef struct { pte_basic_t pte; } pte_t;
> /* 64k pages additionally define a bigger "real PTE" type that gathers
> * the "second half" part of the PTE for pseudo 64k pages
> */
> +#ifdef CONFIG_PPC64
> #ifdef CONFIG_PPC_64K_PAGES
> typedef struct { pte_t pte; unsigned long hidx; } real_pte_t;
> #else
> typedef struct { pte_t pte; } real_pte_t;
> #endif
> +#else
> +#ifdef CONFIG_PPC32_4K_PAGES
> +typedef struct { pte_t pte; } real_pte_t;
> +#else
> +typedef struct { pte_t pte; unsigned long hidx; } real_pte_t;
I don't think you should need a real_pte_t type for the 32-bit
implementation. It's just there because of how we implement
64k granularity page allocation on hardware that only does 4k
translations.
[snip]
> diff --git a/arch/powerpc/include/asm/page_32.h
> b/arch/powerpc/include/asm/page_32.h
> index ebfae53..d176270 100644
> --- a/arch/powerpc/include/asm/page_32.h
> +++ b/arch/powerpc/include/asm/page_32.h
> @@ -20,7 +20,11 @@
> */
> #ifdef CONFIG_PTE_64BIT
> typedef unsigned long long pte_basic_t;
> +#ifdef CONFIG_PPC32_256K_PAGES
> +#define PTE_SHIFT (PAGE_SHIFT - 7)
This doesn't look right. You should be eliding one of the levels of
page table if you don't need it, rather than leaving the bottom level
PTE page largely empty.
[snip]
> +#if (PAGE_SHIFT == 12)
> +/*
> + * PAGE_SIZE 4K
> + * PAGE_SHIFT 12
> + * PTE_SHIFT 9
> + * PMD_SHIFT 21
> + */
> +#define PPC44x_TLBE_SIZE PPC44x_TLB_4K
> +#define PPC44x_PGD_OFF_SH 13 /*(32 - PMD_SHIFT + 2)*/
> +#define PPC44x_PGD_OFF_M1 19 /*(PMD_SHIFT - 2)*/
> +#define PPC44x_PTE_ADD_SH 23 /*32 - PMD_SHIFT + PTE_SHIFT + 3*/
> +#define PPC44x_PTE_ADD_M1 20 /*32 - 3 - PTE_SHIFT*/
> +#define PPC44x_RPN_M2 19 /*31 - PAGE_SHIFT*/
Uh.. you have the formulae for these things right there in the
comments, so why aren't you using those and avoiding this nasty
multiway ifdef...
[snip]
> diff --git a/arch/powerpc/include/asm/thread_info.h
> b/arch/powerpc/include/asm/thread_info.h
> index 9665a26..4e7cd1f 100644
> --- a/arch/powerpc/include/asm/thread_info.h
> +++ b/arch/powerpc/include/asm/thread_info.h
> @@ -15,8 +15,12 @@
> #ifdef CONFIG_PPC64
> #define THREAD_SHIFT 14
> #else
> +#if defined(CONFIG_PPC32_256K_PAGES)
> +#define THREAD_SHIFT 15
Hrm.. more peculiar special cases for 256K pages. I think it might be
clearer if you split the patch into one which supports page sizes up
to 64k, then another that does the extra hacks for 256k pages.
[snip]
> @@ -391,12 +392,14 @@ interrupt_base:
> rlwimi r13,r12,10,30,30
>
> /* Load the PTE */
> - rlwinm r12, r10, 13, 19, 29 /* Compute pgdir/pmd offset */
> + /* Compute pgdir/pmd offset */
> + rlwinm r12, r10, PPC44x_PGD_OFF_SH, PPC44x_PGD_OFF_M1, 29
I agree with others that these constants need better names. Or even
derive the values from PMD_SHIFT or whatnot right here inline, rather
than defining special constants.
[snip]
> diff --git a/arch/powerpc/kernel/head_booke.h
> b/arch/powerpc/kernel/head_booke.h
> index fce2df9..4f802df 100644
> --- a/arch/powerpc/kernel/head_booke.h
> +++ b/arch/powerpc/kernel/head_booke.h
> @@ -20,7 +20,9 @@
> beq 1f; \
> mfspr r1,SPRN_SPRG3; /* if from user, start at top of */\
> lwz r1,THREAD_INFO-THREAD(r1); /* this thread's kernel stack */\
> - addi r1,r1,THREAD_SIZE; \
> + lis r11,[EMAIL PROTECTED]; \
> + ori r11,r11,[EMAIL PROTECTED];
> \
> + add r1,r1,r11;
> \
It would be nice if we could avoid the extra instruction here when the
page sizes isn't big enough to require it.
> 1: subi r1,r1,INT_FRAME_SIZE; /* Allocate an exception frame */\
> mr r11,r1; \
> stw r10,_CCR(r11); /* save various registers */\
> @@ -112,7 +114,8 @@
> andi. r10,r10,MSR_PR; \
> mfspr r11,SPRN_SPRG3; /* if from user, start at top of */\
> lwz r11,THREAD_INFO-THREAD(r11); /* this thread's kernel stack */\
> - addi r11,r11,EXC_LVL_FRAME_OVERHEAD; /* allocate stack frame */\
> + addis r11,r11,[EMAIL PROTECTED]; /* allocate stack frame */\
> + addi r11,r11,[EMAIL PROTECTED]; /* allocate stack frame */\
And here.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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