Was ist der richtige Weg, um die MMU-Übersetzungstabelle zu aktualisieren?
Ich habe MMU auf meinem s3c2440-Board aktiviert (3G-4G-Speicher: das Fehlerattribut). Alles war in Ordnung, wenn ich keinen 3G-4G-Speicher gelesen / geschrieben habe. Um den Seitenfehlervektor zu testen, schrieb ich an eine 0xFF an die 3G-Adresse, wie ich erwartet hatte, habe ich den richtigen Wert von FSR erhalten. Also habe ich dies in _do_page_fault () getan. Der Schritt war wie folgt:
..... // set new page to translation table
.....
invlidate_icache (); // clear icache
clr_dcache (); // wb is used ,clear dcache
invalidate_ttb (); // invalidate translation table
und dann ISR_dataabort zurückgegeben, habe ich die 3G-Adresse gelesen, um die 0xFF zu erhalten, die ich zuvor geschrieben habe. Leider habe ich erneut einen Datenabbruch erhalten. (Ich bin sicher, dass der von mir eingestellte Wert in der Übersetzungstabelle in Ordnung ist.)
Also, was ist der richtige Weg, um die MMU-Übersetzungstabelle zu aktualisieren. Jede Hilfe ist dankbar! Vielen Dank
Hier ist der Hauptcode, den ich verwendet habe (nur für einen Test),(Ich bin ein wenig seltsam für ARM ARCH, daher könnte dieser Code dringend sein.)
/* MMU TTB 0 BASE ATTR */
#define TTB0_FAULT (0|(1<<4)) /* TTB FAULT */
#define TTB0_COARSE (1|(1<<4)) /* COARSE PAGE BASE ADDR */
#define TTB0_SEG (2|(1<<4)) /* SEG BASE ADDR */
#define TTB0_FINE (3|(1<<4)) /* FINE PAGE BASE ADDR */
/* MMU TTB 1 BASE ATTR */
#define TTB1_FAULT (0)
#define TTB1_LPG (1) /* Large page */
#define TTB1_SPG (2) /* small page */
#define TTB1_TPG (3) /* tiny page */
/* domain access priority level */
#define FAULT_PL (0x0) /* domain fault */
#define USR_PL (0x1) /* usr mode */
#define RSV_PL (0x2) /* reserved */
#define SYS_PL (0x3) /* sys mode */
#define DOMAIN_FAULT (0x0<<5) /* fault 0*/
#define DOMAIN_SYS (0x1<<5) /* sys 1*/
#define DOMAIN_USR (0x2<<5) /* usr 2*/
/* C,B bit */
#define CB (3<<2) /* cache_on, write_back */
#define CNB (2<<2) /* cache_on, write_through */
#define NCB (1<<2) /* cache_off,WR_BUF on */
#define NCNB (0<<2) /* cache_off,WR_BUF off */
/* ap 2 bits */
#define AP_FAULT (0<<10) /* access deny */
#define AP_SU_ONLY (1<<10) /* rw su only */
#define AP_USR_RO (2<<10) /* sup=RW, user=RO */
#define AP_RW (3<<10) /* su=RW, user=RW */
/* page dir 1 ap0 */
#define AP0_SU_ONLY (1<<4) /* rw su only */
#define AP0_USR_RO (2<<4) /* sup=RW, user=RO */
#define AP0_RW (3<<4) /* su=RW, user=RW */
/* page dir 1 ap1 */
#define AP1_SU_ONLY (1<<6) /* rw su only */
#define AP1_USR_RO (2<<6) /* sup=RW, user=RO */
#define AP1_RW (3<<6) /* su=RW, user=RW */
/* page dir 1 ap2 */
#define AP2_SU_ONLY (1<<8) /* rw su only */
#define AP2_USR_RO (2<<8) /* sup=RW, user=RO */
#define AP2_RW (3<<8) /* su=RW, user=RW */
/* page dir 1 ap3 */
#define AP3_SU_ONLY (1<<10) /* rw su only */
#define AP3_USR_RO (2<<10) /* sup=RW, user=RO */
#define AP3_RW (3<<10) /* su=RW, user=RW */
#define RAM_START (0x30000000)
#define KERNEL_ENTRY (0x30300000) /* BANK 6 (3M) */
#define KERNEL_STACK (0x3001A000) /* BANK 6 (16K + 64K + 16K + 8K) (8k kernel stack) */
#define IRQ_STACK (0x3001B000) /* 4K IRQ STACK */
#define KERNEL_IMG_SIZE (0x20000)
#define IRQ_STACK (0x3001B000)
/* 16K aignment */
#define TTB_BASE (0x30000000)
#define PAGE_DIR0 (TTB_BASE)
#define TTB_FULL_SIZE (0x4000)
#define PAGE_DIR1 (TTB_BASE+TTB_FULL_SIZE)
#define PAGE_DIR0_SIZE (0x4000) /* 16k */
void _do_page_fault (void)
{
//
...........
//
// read the FSR && get the vaddr && type here
volatile unsigned *page_dir = (volatile unsigned*)(TTB_BASE);
unsigned index = vaddr >> 20,i = 0, j = 0;
unsigned page = 0;
if (!(page_dir[index] & ~(0x3FF) && (type == 0x0B))) { /* page_dir empty */
i = index & ~0x03;
if ( (page_dir[i+0] & ~(0x3FF)) || (page_dir [i+1] & ~(0x3FF))
|| (page_dir[i+2] & ~(0x3FF)) || (page_dir [i+3] & ~(0x3FF)) )
{
panic ( "page dir is bad !\n" ); /* 4 continuous page_dir must be 0 */
}
if (!(page = find_free_page ()))
panic ( "no more free page !\n" ); /* alloc a page page dir*/
page_dir[i+0] = (page + 0x000) | DOMAIN_USR | TTB0_COARSE ; /* small page 1st 1KB */
page_dir[i+1] = (page + 0x400) | DOMAIN_USR | TTB0_COARSE ; /* small page 2nd 1KB */
page_dir[i+2] = (page + 0x800) | DOMAIN_USR | TTB0_COARSE ; /* small page 3rd 1KB */
page_dir[i+3] = (page + 0xC00) | DOMAIN_USR | TTB0_COARSE ; /* small page 4th 1KB */
if (!(page = find_free_page ()))
panic ( "no more free page !\n" ); /* alloc a page page table*/
volatile unsigned *page_tbl = (volatile unsigned*) (page_dir[index] & ~(0x3FF));
*page_tbl = page|AP0_RW|AP1_RW|AP2_RW|AP3_RW| NCNB|TTB1_SPG;/* small page is used */
invalidate_icache ();
for (i = 0; i < 64; i++)
{
for (j = 0;j < 8;j ++)
clr_invalidate_dcache ( (i<<26)|(j<<5) );
}
invalidate_tlb ();
}
........
//
}
/* here is the macros */
#define invalidate_tlb() \
{\
__asm__ __volatile__ (\
"mov r0,#0\n"\
"mcr p15,0,r0,c8,c7,0\n"\
:::"r0" \
);\
}
#define clr_invalidate_dcache(index) \
{\
__asm__ __volatile__ (\
"mcr p15,0,%[i],c7,c14,2\n"\
:: [i]"r"(index)\
);\
}
#define invalidate_icache() \
{\
__asm__ __volatile__ (\
"mov r0,#0\n"\
"mcr p15,0,r0,c7,c5,0\n"\
::: "r0"\
);\
}
#define invalidate_dcache() \
{\
__asm__ __volatile__ (\
"mov r0,#0\n"\
"mcr p15,0,r0,c7,c6,0\n"\
::: "r0"\
);\
}
#define invalidate_idcache() \
{\
__asm__ __volatile__ (\
"mov r0,#0\n"\
"mcr p15,0,r0,c7,c7,0\n"\
:::"r0"\
);\
}\