Add BIOS support for ITLB page fault handling

fallen · Jun 12, 2012 · 4225524 · 4225524
1 parent 3d8f348
commit 4225524
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Showing 7 changed files with 125 additions and 29 deletions.
diff --git a/software/include/hal/mmu.h b/software/include/hal/mmu.h
@@ -62,6 +62,22 @@ struct mmu_mapping {
 			 "xor r0, r0, r0":::"r11"); \
 } while(0);
 
+#define enable_itlb() do { \
+	asm volatile	("xor r11, r11, r11\n\t" \
+			 "ori r11, r11, 0x10\n\t" \
+			 "wcsr tlbctrl, r11\n\t" \
+			 "xor r0, r0, r0":::"r11"); \
+} while(0);
+
+#define disable_itlb() do { \
+	asm volatile	("xor r11, r11, r11\n\t" \
+			 "ori r11, r11, 0x8\n\t" \
+			 "wcsr tlbctrl, r11\n\t" \
+			 "xor r0, r0, r0\n\t" \
+			 "xor r0, r0, r0\n\t" \
+			 "xor r0, r0, r0":::"r11"); \
+} while(0);
+
 void mmu_dtlb_map(unsigned int vpfn, unsigned int pfn);
 
 #endif
diff --git a/software/mmu-bios/Makefile b/software/mmu-bios/Makefile
@@ -1,7 +1,7 @@
 MMDIR=../..
 include $(MMDIR)/software/include.mak
 
-OBJECTS=crt0.o main.o dtlb_load_test.o mmu.o isr.o vsnprintf-nofloat.o dtlb_miss_handler.o dtlb_exception_handling_tests.o
+OBJECTS=crt0.o main.o dtlb_load_test.o mmu.o isr.o vsnprintf-nofloat.o tlb_miss_handler.o dtlb_exception_handling_tests.o
 SEGMENTS=-j .text -j .data -j .rodata
 
 all: bios.bin

diff --git a/software/mmu-bios/crt0.S b/software/mmu-bios/crt0.S
@@ -119,6 +119,15 @@ _dtlb_miss_exception_handler:
 	nop
 	nop
 
+_itlb_miss_exception_handler:
+	sw	(sp+0), ra
+	calli	.save_all
+	calli	itlb_miss_handler
+	bi	.restore_all_and_eret
+	nop
+	nop
+	nop
+
 macaddress:
 	.byte 0x10
 	.byte 0xe2

diff --git a/software/mmu-bios/dtlb_miss_handler.c b/software/mmu-bios/dtlb_miss_handler.c
diff --git a/software/mmu-bios/main.c b/software/mmu-bios/main.c
@@ -1,6 +1,8 @@
 #include "main.h"
 #include <base/mmu.h>
 
+extern void call_function_with_itlb_enabled(void (*f)(void));
+
 void uart_write(char c)
 {
 	unsigned int oldmask;
@@ -74,7 +76,7 @@ int printf(const char *fmt, ...)
 
 void f(void) {
 	CSR_UART_RXTX = '@';
-	asm volatile("bi f" ::: ); // We intinitely loop to f()
+//	asm volatile("bi f" ::: ); // We intinitely loop to f()
 	asm volatile("xor r0, r0, r0\n\t"
 		     "xor r0, r0, r0" ::: );
 }
@@ -92,9 +94,15 @@ void itlbtest(void) {
 	f_addr = 0x44004000;
 	printf("Mapping f() into virtual memory at 0x%08X [physical == 0x%08X]\n", f_addr, f_addr+0x1000);
 
+	mmu_map(0x44003000, 0x44003000, DTLB_MAPPING | MAPPING_CAN_READ | MAPPING_CAN_WRITE);
+	mmu_map(stack, stack, DTLB_MAPPING | MAPPING_CAN_READ | MAPPING_CAN_WRITE);
 	mmu_map(f_addr, f_addr + 0x1000, ITLB_MAPPING | MAPPING_CAN_READ);
+	mmu_map(itlbtest, itlbtest, ITLB_MAPPING | MAPPING_CAN_READ);
+	mmu_map(call_function_with_itlb_enabled, call_function_with_itlb_enabled, ITLB_MAPPING | MAPPING_CAN_READ);
 	puts("Mapping DONE");
 
+	mmu_itlb_invalidate(f_addr);
+
 	// We copy f's code to 0x44005000
 	for (p = f, pdest = 0x44005000 ; p < f + 0x1000 ; p++, pdest++)
 		*pdest = *p;
@@ -105,7 +113,11 @@ void itlbtest(void) {
 	puts("Instruction and Data caches have been invalidated");
 
 	call_function_with_itlb_enabled(f_addr);
+	disable_dtlb();
+	disable_itlb();
 	puts("Call DONE");
+	while(1)
+		asm volatile("xor r0, r0, r0");
 }
 
 int main(int argc, char **argv)

diff --git a/software/mmu-bios/mmu.c b/software/mmu-bios/mmu.c
@@ -47,6 +47,16 @@ inline void mmu_dtlb_invalidate(unsigned int vaddr)
 		      "wcsr tlbctrl, r11":::"r11");
 }
 
+inline void mmu_itlb_invalidate(unsigned int vaddr)
+{
+	asm volatile ("ori %0, %0, 0\n\t"
+		      "wcsr tlbvaddr, %0"::"r"(vaddr):);
+
+	asm volatile ("xor r11, r11, r11\n\t"
+		      "ori r11, r11, 0x20\n\t"
+		      "wcsr tlbctrl, r11":::"r11");
+}
+
 struct mmu_mapping mappings[MAX_MMU_SLOTS];
 
 
@@ -102,7 +112,7 @@ unsigned int mmu_map(unsigned int vaddr, unsigned int paddr, char metadata) {
 }
 
 unsigned int get_mmu_mapping_for(unsigned int vaddr) {
-	int i;
+	unsigned int i;
 	vaddr = get_pfn(vaddr);
 
 	for (i = 0 ; i < MAX_MMU_SLOTS ; ++i)
@@ -112,6 +122,28 @@ unsigned int get_mmu_mapping_for(unsigned int vaddr) {
 	return A_BAD_ADDR;
 }
 
+unsigned char is_dtlb_mapping(unsigned int vaddr) {
+	unsigned int i;
+	vaddr = get_pfn(vaddr);
+
+	for (i = 0 ; i < MAX_MMU_SLOTS ; ++i)
+		if ((mappings[i].vaddr == vaddr) && (mappings[i].metadata & (MAPPING_IS_VALID)) && (mappings[i].metadata & (DTLB_MAPPING)))
+			return 1;
+
+	return 0;
+}
+
+unsigned char is_itlb_mapping(unsigned int vaddr) {
+	unsigned int i;
+	vaddr = get_pfn(vaddr);
+
+	for (i = 0 ; i < MAX_MMU_SLOTS ; ++i)
+		if ((mappings[i].vaddr == vaddr) && (mappings[i].metadata & (MAPPING_IS_VALID)) && (mappings[i].metadata & (ITLB_MAPPING)))
+			return 1;
+
+	return 0;
+}
+
 unsigned char remove_mmu_mapping_for(unsigned int vaddr) {
 	int i;
 	vaddr = get_pfn(vaddr);
@@ -195,6 +227,9 @@ unsigned int write_word_with_mmu_enabled(register unsigned int vaddr, register u
 
 void call_function_with_itlb_enabled(void (*f)(void))
 {
+	register unsigned int stack;
+	asm volatile("mv %0, sp" : "=r"(stack) :: );
+	printf("call stack == 0x%08x\n", stack);
 	asm volatile(
 		"xor r11, r11, r11\n\t"
 		"ori r11, r11, 0x10\n\t"

diff --git a/software/mmu-bios/tlb_miss_handler.c b/software/mmu-bios/tlb_miss_handler.c
@@ -0,0 +1,50 @@
+#include <hal/mmu.h>
+#include <base/mmu.h>
+
+void dtlb_miss_handler(void)
+{
+	unsigned int vaddr, paddr;
+
+	// retrieve virtual address which caused the page fault
+	asm volatile("rcsr %0, dtlbma" : "=r"(vaddr) :: );
+
+	/*
+	* check if there is an existing mapping for that virtual address
+	* if yes: refill the DTLB with it
+	* if not: we panic() !
+	*/
+	paddr = get_mmu_mapping_for(vaddr);
+	if (paddr == A_BAD_ADDR || !is_dtlb_mapping(vaddr))
+	{
+		puts("Unrecoverable DTLB page fault !");
+		panic();
+	}
+
+	printf("Refilling DTLB with mapping 0x%08X->0x%08X\n", vaddr, paddr);
+	mmu_dtlb_map(vaddr, paddr);
+}
+
+void itlb_miss_handler(void)
+{
+	unsigned int vaddr, paddr;
+
+	asm volatile("rcsr %0, itlbma" : "=r"(vaddr) :: );
+	printf("Address 0x%08X caused an ITLB page fault\n", vaddr);
+
+	paddr = get_mmu_mapping_for(vaddr);
+	if (paddr == A_BAD_ADDR)
+	{
+		puts("No such mapping !");
+		puts("Unrecoverable ITLB page fault !");
+		panic();
+	}
+
+	if (!is_itlb_mapping(vaddr))
+	{
+		puts("Mapping not in ITLB");
+		panic();
+	}
+
+	printf("Refilling ITLB with mapping 0x%08X->0x%08X\n", vaddr, paddr);
+	mmu_itlb_map(vaddr, paddr);
+}