ddb: Fix accessing high memory

User processes loaded in high memory are not visible to ddb through the
direct mapping. We can however read/write data through copy_from/to_phys.

2 files changed, 61 insertions, 20 deletions

diff --git a/i386/i386/db_interface.c b/i386/i386/db_interface.c
index 1a7070e3..7761571d 100644
--- a/i386/i386/db_interface.c
+++ b/i386/i386/db_interface.c
@@ -39,6 +39,7 @@
 #include <i386/pmap.h>
 #include <i386/proc_reg.h>
 #include <i386/locore.h>
+#include <i386at/biosmem.h>
 #include "gdt.h"
 #include "trap.h"
 
@@ -442,10 +443,10 @@ kdb_kentry(
 boolean_t db_no_vm_fault = TRUE;
 
 int
-db_user_to_kernel_address(
+db_user_to_phys_address(
 	const task_t	task,
 	vm_offset_t	addr,
-	vm_offset_t	*kaddr,
+	vm_offset_t	*paddr,
 	int		flag)
 {
 	pt_entry_t *ptp;
@@ -470,7 +471,29 @@ db_user_to_kernel_address(
 	    }
 	    return(-1);
 	}
-	*kaddr = ptetokv(*ptp) + (addr & (INTEL_PGBYTES-1));
+
+	*paddr = pte_to_pa(*ptp) + (addr & (INTEL_PGBYTES-1));
+	return(0);
+}
+
+int
+db_user_to_kernel_address(
+	const task_t	task,
+	vm_offset_t	addr,
+	vm_offset_t	*kaddr,
+	int		flag)
+{
+	vm_offset_t paddr;
+
+	if (db_user_to_phys_address(task, addr, &paddr, flag) < 0)
+	    return(-1);
+
+	if (paddr >= biosmem_directmap_end()) {
+	    db_printf("\naddr %08x is stored in highmem at physical %016llx, accessing it is not supported yet\n", addr, (unsigned long long) paddr);
+	    return(-1);
+	}
+
+	*kaddr = phystokv(paddr);
 	return(0);
 }
 
@@ -487,7 +510,7 @@ db_read_bytes(
 {
 	char		*src;
 	int		n;
-	vm_offset_t	kern_addr;
+	vm_offset_t	phys_addr;
 
 	src = (char *)addr;
 	if ((addr >= VM_MIN_KERNEL_ADDRESS && addr < VM_MAX_KERNEL_ADDRESS) || task == TASK_NULL) {
@@ -504,16 +527,14 @@ db_read_bytes(
 	    return TRUE;
 	}
 	while (size > 0) {
-	    if (db_user_to_kernel_address(task, addr, &kern_addr, 1) < 0)
+	    if (db_user_to_phys_address(task, addr, &phys_addr, 1) < 0)
 		return FALSE;
-	    src = (char *)kern_addr;
 	    n = intel_trunc_page(addr+INTEL_PGBYTES) - addr;
 	    if (n > size)
 		n = size;
 	    size -= n;
 	    addr += n;
-	    while (--n >= 0)
-		*data++ = *src++;
+	    copy_from_phys(phys_addr, (vm_offset_t) data, n);
 	}
 	return TRUE;
 }
@@ -596,21 +617,18 @@ db_write_bytes_user_space(
 	char		*data,
 	task_t		task)
 {
-	char		*dst;
 	int		n;
-	vm_offset_t	kern_addr;
+	vm_offset_t	phys_addr;
 
 	while (size > 0) {
-	    if (db_user_to_kernel_address(task, addr, &kern_addr, 1) < 0)
+	    if (db_user_to_phys_address(task, addr, &phys_addr, 1) < 0)
 		return;
-	    dst = (char *)kern_addr;
 	    n = intel_trunc_page(addr+INTEL_PGBYTES) - addr;
 	    if (n > size)
 		n = size;
 	    size -= n;
 	    addr += n;
-	    while (--n >= 0)
-		*dst++ = *data++;
+	    copy_to_phys((vm_offset_t) data, phys_addr, n);
 	}
 }
 
@@ -621,7 +639,7 @@ db_check_access(
 	task_t		task)
 {
 	int	n;
-	vm_offset_t	kern_addr;
+	vm_offset_t	phys_addr;
 
 	if (addr >= VM_MIN_KERNEL_ADDRESS) {
 	    if (kernel_task == TASK_NULL)
@@ -633,7 +651,7 @@ db_check_access(
 	    task = current_thread()->task;
 	}
 	while (size > 0) {
-	    if (db_user_to_kernel_address(task, addr, &kern_addr, 0) < 0)
+	    if (db_user_to_phys_address(task, addr, &phys_addr, 0) < 0)
 		return FALSE;
 	    n = intel_trunc_page(addr+INTEL_PGBYTES) - addr;
 	    if (n > size)
@@ -651,7 +669,7 @@ db_phys_eq(
 	const task_t	task2,
 	vm_offset_t	addr2)
 {
-	vm_offset_t	kern_addr1, kern_addr2;
+	vm_offset_t	phys_addr1, phys_addr2;
 
 	if (addr1 >= VM_MIN_KERNEL_ADDRESS || addr2 >= VM_MIN_KERNEL_ADDRESS)
 	    return FALSE;
@@ -662,10 +680,10 @@ db_phys_eq(
 		return FALSE;
 	    task1 = current_thread()->task;
 	}
-	if (db_user_to_kernel_address(task1, addr1, &kern_addr1, 0) < 0
-		|| db_user_to_kernel_address(task2, addr2, &kern_addr2, 0) < 0)
+	if (db_user_to_phys_address(task1, addr1, &phys_addr1, 0) < 0
+		|| db_user_to_phys_address(task2, addr2, &phys_addr2, 0) < 0)
 	    return FALSE;
-	return(kern_addr1 == kern_addr2);
+	return(phys_addr1 == phys_addr2);
 }
 
 #define DB_USER_STACK_ADDR		(VM_MIN_KERNEL_ADDRESS)
diff --git a/i386/intel/pmap.h b/i386/intel/pmap.h
index 0ca03148..f24b3a71 100644
--- a/i386/intel/pmap.h
+++ b/i386/intel/pmap.h
@@ -494,6 +494,29 @@ extern void pmap_zero_page (phys_addr_t);
 extern void pmap_copy_page (phys_addr_t, phys_addr_t);
 
 /*
+ *	copy_to_phys(src_addr_v, dst_addr_p, count)
+ *
+ *	Copy virtual memory to physical memory
+ */
+extern void
+copy_to_phys(
+	vm_offset_t 	src_addr_v, 
+	phys_addr_t 	dst_addr_p,
+	int 		count);
+
+/*
+ *	copy_from_phys(src_addr_p, dst_addr_v, count)
+ *
+ *	Copy physical memory to virtual memory.  The virtual memory
+ *	is assumed to be present (e.g. the buffer pool).
+ */
+extern void
+copy_from_phys(
+	phys_addr_t 	src_addr_p, 
+	vm_offset_t 	dst_addr_v,
+	int 		count);
+
+/*
  *  kvtophys(addr)
  *
  *  Convert a kernel virtual address to a physical address