--- /dev/null
+/*
+ * Copyright (c) 2012 Apple Inc. All rights reserved.
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
+ *
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ *
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ *
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
+ */
+
+#if ALTERNATE_DEBUGGER
+
+/*
+
+The alternate debugger feature is enabled by setting the boot arg "alternate_debugger_init"
+to the size of memory that should be set aside for the debugger. The boot arg
+"alternate_debugger_init_pages" is used to allocate more vmpages that the alternate debugger
+may use to do additional VA->PA mappings. The boot-arg "alternate_debugger_pause_for_load_at_boot"
+will halt the system so that the debugger can be loaded early in the boot cycle -- once the
+alternate debugger code is loaded, a register must be set to a 1 to continue the boot process.
+
+Here's an example:
+nvram boot-arg="alternate_debugger_init=0x800000 alternate_debugger_init_pages=0x8000 alternate_debugger_pause_for_load_at_boot=1"
+
+The low memory global lgAltDebugger will contain the address of the allocated memory for
+the alternate debugger. On arm64, the address of this low memory global is 0xffffff8000002048.
+
+At any point after the low memory global is non-zero, Astris may be used to halt the cpu
+and load the alternate debugger:
+
+If no alternate debugger is given, but alternate_debugger_init has been specified, and the
+kernel debugger is entered, the string ">MT<" is printed and normal processing continues.
+
+Anytime the alternate debugger is entered, the osversion string is modified to start with "ALT"
+so that panic reports can clearly indicated that some kernel poking may have occurred, and
+the panic should be weighted accordingly.
+
+*/
+
+#include <arm64/alternate_debugger.h>
+
+#include <kern/kalloc.h>
+#include <arm64/lowglobals.h>
+#include <arm/caches_internal.h>
+#include <kern/cpu_data.h>
+#include <arm/pmap.h>
+#include <pexpert/pexpert.h>
+#include <vm/vm_map.h>
+#include <vm/vm_kern.h>
+#include <libkern/version.h>
+
+void kprintf(const char *fmt, ...);
+
+
+static mach_vm_address_t alt_code;
+static mach_vm_size_t alt_size;
+static mach_vm_address_t alt_pages;
+static mach_vm_size_t alt_pages_size;
+
+typedef void (*t_putc_fn)(char c);
+typedef void (*t_call_altdbg_fn)(mach_vm_size_t size, mach_vm_address_t pages, mach_vm_size_t pages_size, t_putc_fn putc_address );
+
+// used as a temporary alternate debugger until another is loaded
+extern void alternate_debugger_just_return(__unused mach_vm_size_t size, __unused mach_vm_address_t pages, __unused mach_vm_size_t pages_size, t_putc_fn putc_address);
+extern void *alternate_debugger_just_return_end;
+
+// public entry to the alternate debugger
+void alternate_debugger_enter(void)
+{
+ if ( alt_code != 0 ) {
+ disable_preemption();
+
+ printf("########## Going to call ALTERNATE DEBUGGER\n");
+
+ // make sure it isn't in the cache
+ assert((alt_size & 0xFFFFFFFF00000000) == 0);
+ flush_dcache(alt_code, (unsigned int)alt_size, 0);
+
+ // set the code to execute
+ pmap_protect(kernel_map->pmap, alt_code, alt_code+alt_size, VM_PROT_READ|VM_PROT_EXECUTE);
+
+ // black-spot the OS version for any panic reports that occur because of entering the alternate debugger
+ if ( *osversion ) {
+ memcpy(osversion, "ALT", 3); // Version set, stomp on the begining of it
+ } else {
+ strncpy(osversion, "ALT - Version Not Set Yet", OSVERSIZE);
+ }
+
+ kprintf("########## Calling ALTERNATE DEBUGGER (size %lld, pages 0x%llx, pages_size 0x%llx, putc %p\n", alt_size, alt_pages, alt_pages_size, &consdebug_putc_unbuffered);
+ ((t_call_altdbg_fn)alt_code)(alt_size, alt_pages, alt_pages_size, &consdebug_putc_unbuffered);
+ kprintf("########## Returned from calling ALTERNATE DEBUGGER\n");
+
+ enable_preemption();
+ }
+}
+
+// public entry to check boot args and init accordingly
+void alternate_debugger_init(void)
+{
+ // use the alternate debugger
+ if( PE_parse_boot_argn("alternate_debugger_init", (void*)&alt_size, sizeof(alt_size)) )
+ {
+ vm_offset_t alt_va = 0;
+
+ kprintf("########## ALTERNATE_DEBUGGER\n");
+
+ PE_parse_boot_argn("alternate_debugger_init_pages", (void*)&alt_pages_size, sizeof(alt_pages_size));
+
+ alt_size = vm_map_round_page(alt_size,
+ VM_MAP_PAGE_MASK(kernel_map));
+ alt_pages_size = vm_map_round_page(alt_pages_size,
+ VM_MAP_PAGE_MASK(kernel_map));
+
+ kern_return_t kr = KERN_SUCCESS;
+ kr = kmem_alloc_contig(kernel_map, &alt_va, alt_size, VM_MAP_PAGE_MASK(kernel_map), 0, 0, KMA_NOPAGEWAIT | KMA_KOBJECT | KMA_LOMEM, VM_KERN_MEMORY_DIAG);
+ if( kr != KERN_SUCCESS)
+ {
+ kprintf("########## ALTERNATE_DEBUGGER FAILED kmem_alloc_contig with %d\n", kr);
+ alt_va = 0;
+ }
+ else {
+ if ( alt_pages_size ) {
+ alt_pages = (vm_offset_t) kalloc((vm_size_t) alt_pages_size);
+ }
+ }
+
+ kprintf("########## Initializing ALTERNATE DEBUGGER : [alloc size 0x%llx @0x%lx] [pages_size 0x%llx @0x%llx] -- lowmem pointer at %p\n",
+ alt_size, alt_va, alt_pages_size, alt_pages, &lowGlo.lgAltDebugger );
+
+ if ( alt_va ) {
+ uintptr_t just_return_size = (uintptr_t)&alternate_debugger_just_return_end - (uintptr_t)&alternate_debugger_just_return;
+ assert(just_return_size <= alt_size); // alt_size is page-rounded, just_return_size should be much less than a page.
+ // install a simple return vector
+ memcpy((void*)alt_va, &alternate_debugger_just_return, just_return_size);
+
+ // code is ready, enable the pointers to it
+ lowGlo.lgAltDebugger = alt_code = alt_va;
+
+#if 1
+ // DEBUG for BRING-UP testing
+ unsigned int alt_init_test;
+ if(PE_parse_boot_argn("alternate_debugger_pause_for_load_at_boot", &alt_init_test, sizeof(alt_init_test)) ) {
+
+ // debug!!
+ kprintf("########## Waiting for ALTERNATE DEBUGGER to load (in file %s).... to continue, set register to 1", __FILE__ );
+ volatile int ii = 0;
+ while(!ii)
+ ;
+ kprintf("\n");
+ alternate_debugger_enter();
+ }
+#endif
+ }
+ }
+}
+
+#endif /* ALTERNATE_DEBUGGER */
projects / apple / xnu.git / blobdiff