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microblaze: Improve TLB calculation for small systems

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Systems with small amount of memory need to be handled
differently. Linux can't allocate the whole 32MB with two TLBs
because then there is no MMU protection.

Signed-off-by: Michal Simek <monstr@monstr.eu>
This commit is contained in:
Michal Simek 2010-02-08 16:41:38 +01:00
parent 3a1d26769f
commit 95b0f9ea66
6 changed files with 120 additions and 11 deletions
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4
arch/microblaze/Kconfig
View File

@ -259,6 +259,10 @@ config MICROBLAZE_32K_PAGES
endchoice
config KERNEL_PAD
hex "Kernel PAD for unpacking" if ADVANCED_OPTIONS
default "0x80000" if MMU
endmenu
source "mm/Kconfig"

3
arch/microblaze/include/asm/setup.h
View File

@ -39,7 +39,8 @@ extern void of_platform_reset_gpio_probe(void);
void time_init(void);
void init_IRQ(void);
void machine_early_init(const char *cmdline, unsigned int ram,
unsigned int fdt, unsigned int msr);
unsigned int fdt, unsigned int msr, unsigned int tlb0,
unsigned int tlb1);
void machine_restart(char *cmd);
void machine_shutdown(void);

1
arch/microblaze/include/asm/system.h
View File

@ -83,6 +83,7 @@ void default_idle(void);
void free_init_pages(char *what, unsigned long begin, unsigned long end);
void free_initmem(void);
extern char *klimit;
extern unsigned long kernel_tlb;
extern void ret_from_fork(void);
extern void *alloc_maybe_bootmem(size_t size, gfp_t mask);

98
arch/microblaze/kernel/head.S
View File

@ -168,6 +168,53 @@ _invalidate:
addik r3,r0, CONFIG_KERNEL_START /* Load the kernel virtual address */
tophys(r4,r3) /* Load the kernel physical address */
/* start to do TLB calculation */
addik r12, r0, _end
rsub r12, r3, r12
addik r12, r12, CONFIG_KERNEL_PAD /* that's the pad */
or r9, r0, r0 /* TLB0 = 0 */
or r10, r0, r0 /* TLB1 = 0 */
addik r11, r12, -0x1000000
bgei r11, GT16 /* size is greater than 16MB */
addik r11, r12, -0x0800000
bgei r11, GT8 /* size is greater than 8MB */
addik r11, r12, -0x0400000
bgei r11, GT4 /* size is greater than 4MB */
/* size is less than 4MB */
addik r11, r12, -0x0200000
bgei r11, GT2 /* size is greater than 2MB */
addik r9, r0, 0x0100000 /* TLB0 must be 1MB */
addik r11, r12, -0x0100000
bgei r11, GT1 /* size is greater than 1MB */
/* TLB1 is 0 which is setup above */
bri tlb_end
GT4: /* r11 contains the rest - will be either 1 or 4 */
ori r9, r0, 0x400000 /* TLB0 is 4MB */
bri TLB1
GT16: /* TLB0 is 16MB */
addik r9, r0, 0x1000000 /* means TLB0 is 16MB */
TLB1:
/* must be used r2 because of substract if failed */
addik r2, r11, -0x0400000
bgei r2, GT20 /* size is greater than 16MB */
/* size is >16MB and <20MB */
addik r11, r11, -0x0100000
bgei r11, GT17 /* size is greater than 17MB */
/* kernel is >16MB and < 17MB */
GT1:
addik r10, r0, 0x0100000 /* means TLB1 is 1MB */
bri tlb_end
GT2: /* TLB0 is 0 and TLB1 will be 4MB */
GT17: /* TLB1 is 4MB - kernel size <20MB */
addik r10, r0, 0x0400000 /* means TLB1 is 4MB */
bri tlb_end
GT8: /* TLB0 is still zero that's why I can use only TLB1 */
GT20: /* TLB1 is 16MB - kernel size >20MB */
addik r10, r0, 0x1000000 /* means TLB1 is 16MB */
tlb_end:
/*
* Configure and load two entries into TLB slots 0 and 1.
* In case we are pinning TLBs, these are reserved in by the
@ -177,16 +224,56 @@ _invalidate:
andi r4,r4,0xfffffc00 /* Mask off the real page number */
ori r4,r4,(TLB_WR | TLB_EX) /* Set the write and execute bits */
/* TLB0 can be zeroes that's why we not setup it */
beqi r9, jump_over
/* look at the code below */
ori r30, r0, 0x200
andi r29, r9, 0x100000
bneid r29, 1f
addik r30, r30, 0x80
andi r29, r9, 0x400000
bneid r29, 1f
addik r30, r30, 0x80
andi r29, r9, 0x1000000
bneid r29, 1f
addik r30, r30, 0x80
1:
ori r11, r30, 0
andi r3,r3,0xfffffc00 /* Mask off the effective page number */
ori r3,r3,(TLB_VALID | TLB_PAGESZ(PAGESZ_16M))
ori r3,r3,(TLB_VALID)
or r3, r3, r11
mts rtlbx,r0 /* TLB slow 0 */
mts rtlblo,r4 /* Load the data portion of the entry */
mts rtlbhi,r3 /* Load the tag portion of the entry */
addik r4, r4, 0x01000000 /* Map next 16 M entries */
addik r3, r3, 0x01000000
jump_over:
/* TLB1 can be zeroes that's why we not setup it */
beqi r10, jump_over2
/* look at the code below */
ori r30, r0, 0x200
andi r29, r10, 0x100000
bneid r29, 1f
addik r30, r30, 0x80
andi r29, r10, 0x400000
bneid r29, 1f
addik r30, r30, 0x80
andi r29, r10, 0x1000000
bneid r29, 1f
addik r30, r30, 0x80
1:
ori r12, r30, 0
addk r4, r4, r9 /* previous addr + TLB0 size */
addk r3, r3, r9
andi r3,r3,0xfffffc00 /* Mask off the effective page number */
ori r3,r3,(TLB_VALID)
or r3, r3, r12
ori r6,r0,1 /* TLB slot 1 */
mts rtlbx,r6
@ -194,6 +281,7 @@ _invalidate:
mts rtlblo,r4 /* Load the data portion of the entry */
mts rtlbhi,r3 /* Load the tag portion of the entry */
jump_over2:
/*
* Load a TLB entry for LMB, since we need access to
* the exception vectors, using a 4k real==virtual mapping.
@ -237,8 +325,8 @@ start_here:
* Please see $(ARCH)/mach-$(SUBARCH)/setup.c for
* the function.
*/
addik r9, r0, machine_early_init
brald r15, r9
addik r11, r0, machine_early_init
brald r15, r11
nop
#ifndef CONFIG_MMU

11
arch/microblaze/kernel/setup.c
View File

@ -97,8 +97,11 @@ inline unsigned get_romfs_len(unsigned *addr)
}
#endif /* CONFIG_MTD_UCLINUX_EBSS */
unsigned long kernel_tlb;
void __init machine_early_init(const char *cmdline, unsigned int ram,
unsigned int fdt, unsigned int msr)
unsigned int fdt, unsigned int msr, unsigned int tlb0,
unsigned int tlb1)
{
unsigned long *src, *dst;
unsigned int offset = 0;
@ -145,6 +148,12 @@ void __init machine_early_init(const char *cmdline, unsigned int ram,
setup_early_printk(NULL);
#endif
/* setup kernel_tlb after BSS cleaning
* Maybe worth to move to asm code */
kernel_tlb = tlb0 + tlb1;
/* printk("TLB1 0x%08x, TLB0 0x%08x, tlb 0x%x\n", tlb0,
tlb1, kernel_tlb); */
printk("Ramdisk addr 0x%08x, ", ram);
if (fdt)
printk("FDT at 0x%08x\n", fdt);

14
arch/microblaze/mm/init.c
View File

@ -398,10 +398,16 @@ asmlinkage void __init mmu_init(void)
machine_restart(NULL);
}
if ((u32) memblock.memory.regions[0].size < 0x1000000) {
printk(KERN_EMERG "Memory must be greater than 16MB\n");
if ((u32) memblock.memory.regions[0].size < 0x400000) {
printk(KERN_EMERG "Memory must be greater than 4MB\n");
machine_restart(NULL);
}
if ((u32) memblock.memory.regions[0].size < kernel_tlb) {
printk(KERN_EMERG "Kernel size is greater than memory node\n");
machine_restart(NULL);
}
/* Find main memory where the kernel is */
memory_start = (u32) memblock.memory.regions[0].base;
lowmem_size = memory_size = (u32) memblock.memory.regions[0].size;
@ -462,11 +468,11 @@ void __init *early_get_page(void)
p = alloc_bootmem_pages(PAGE_SIZE);
} else {
/*
* Mem start + 32MB -> here is limit
* Mem start + kernel_tlb -> here is limit
* because of mem mapping from head.S
*/
p = __va(memblock_alloc_base(PAGE_SIZE, PAGE_SIZE,
memory_start + 0x2000000));
memory_start + kernel_tlb));
}
return p;
}