* Added option "-b <count>" to "dis". It causes up to <count>

instructions to be printed before the given address. The feature is
  implemented by looking up the address of the previous symbol for the
  given address and disassembling forward (two passes).
* The instuction at given address is printed highlighted (blue).


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@27191 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/add-ons/kernel/debugger/disasm/Jamfile

@@ -1,6 +1,6 @@
 SubDir HAIKU_TOP src add-ons kernel debugger disasm ;
 
-UsePrivateHeaders kernel ;
+UsePrivateKernelHeaders ;
 
 KernelAddon <kdebug>disasm :
 	disasm.cpp

src/add-ons/kernel/debugger/disasm/disasm.cpp

@@ -5,6 +5,8 @@
 
 #include <arch/debug.h>
 #include <debug.h>
+#include <elf.h>
+#include <kernel.h>
 #include <signal.h>
 
 #include "disasm_arch.h"
@@ -13,15 +15,29 @@
 int
 disasm_command(int argc, char **argv)
 {
-	if (argc > 3) {
+	int argi = 1;
+
+	// get back count
+	uint64 backCount = 0;
+	if (argi < argc && strcmp(argv[argi], "-b") == 0) {
+		if (++argi >= argc) {
+			print_debugger_command_usage(argv[0]);
+			return 0;
+		}
+
+		if (!evaluate_debug_expression(argv[argi++], &backCount, false))
+			return 0;
+	}
+
+	if (argi + 2 < argc) {
 		print_debugger_command_usage(argv[0]);
 		return 0;
 	}
 
 	// get PC
 	uint64 pc;
-	if (argc >= 2) {
-		if (!evaluate_debug_expression(argv[1], &pc, false))
+	if (argi < argc) {
+		if (!evaluate_debug_expression(argv[argi++], &pc, false))
 			return 0;
 	} else {
 		pc = (addr_t)arch_debug_get_interrupt_pc();
@@ -33,14 +49,37 @@ disasm_command(int argc, char **argv)
 
 	// get count
 	uint64 count = 10;
-	if (argc >= 3) {
-		if (!evaluate_debug_expression(argv[2], &count, false))
+	if (argi < argc) {
+		if (!evaluate_debug_expression(argv[argi++], &count, false))
 			return 0;
 	}
 
 	// TODO: autoincrement
 
-	disasm_arch_dump_insns((addr_t)pc, count);
+	// if back count is given, compute base address
+	addr_t baseAddress = 0;
+	if (backCount > 0) {
+		status_t error;
+		const char *symbol;
+		const char *imageName;
+		bool exactMatch;
+
+		if (IS_KERNEL_ADDRESS(pc)) {
+			error = elf_debug_lookup_symbol_address(pc, &baseAddress, &symbol,
+				&imageName, &exactMatch);
+		} else {
+			error = elf_debug_lookup_user_symbol_address(
+				debug_get_debugged_thread()->team, pc, &baseAddress, &symbol,
+				&imageName, &exactMatch);
+		}
+
+		if (error != B_OK) {
+			baseAddress = 0;
+			backCount = 0;
+		}
+	}
+
+	disasm_arch_dump_insns((addr_t)pc, count, baseAddress, backCount);
 	return 0;
 }
 
@@ -56,11 +95,14 @@ std_ops(int32 op, ...)
 			return err;
 		return add_debugger_command_etc("dis", disasm_command,
 			"Print disassembly at address",
-			"[ <address>  [ <count> ] ]\n"
+			"[ -b <back count> ] [ <address>  [ <count> ] ]\n"
 			"Prints disassembly at address.\n"
-			"  <address>   - Address at which to start disassembling\n"
-			"                (defaults to current PC).\n"
-			"  <count>     - Number of instructions to disassemble.\n", 0);
+			"  <address>        - Address at which to start disassembling\n"
+			"                     (defaults to current PC).\n"
+			"  <count>          - Number of instructions to disassemble\n"
+			"                     starting at <address>.\n"
+			"  -b <back count>  - Number of instruction to disassemble before\n"
+			"                     <address>.\n", 0);
 	} else if (op == B_MODULE_UNINIT) {
 		remove_debugger_command("dis", disasm_command);
 		return disasm_arch_fini();

src/add-ons/kernel/debugger/disasm/disasm_arch.h

@@ -12,7 +12,8 @@ extern "C" {
 extern status_t disasm_arch_init();
 extern status_t disasm_arch_fini();
 
-extern status_t disasm_arch_dump_insns(addr_t where, int count);
+extern status_t disasm_arch_dump_insns(addr_t where, int count,
+	addr_t baseAddress, int backCount);
 
 #ifdef __cplusplus
 }

src/add-ons/kernel/debugger/disasm/m68k/disasm_arch.cpp

@@ -8,7 +8,8 @@
 #include "disasm_arch.h"
 
 status_t
-disasm_arch_dump_insns(addr_t where, int count)
+disasm_arch_dump_insns(addr_t where, int count, addr_t baseAddress,
+	int backCount)
 {
 	return ENOENT;
 }

src/add-ons/kernel/debugger/disasm/ppc/disasm_arch.cpp

@@ -8,7 +8,8 @@
 #include "disasm_arch.h"
 
 status_t
-disasm_arch_dump_insns(addr_t where, int count)
+disasm_arch_dump_insns(addr_t where, int count, addr_t baseAddress,
+	int backCount)
 {
 	return ENOENT;
 }

src/add-ons/kernel/debugger/disasm/x86/Jamfile

@@ -7,7 +7,7 @@ DEFINES += __UD_STANDALONE__ ;
 DEFINES += assert=disasm_arch_assert ;
 DEFINES += __assert_fail=disasm_arch_assert ;
 
-local libUdis86Sources = 
+local libUdis86Sources =
 	decode.c
 	input.c
 	itab.c

src/add-ons/kernel/debugger/disasm/x86/disasm_arch.cpp

@@ -9,6 +9,7 @@
 #include "disasm_arch.h"
 #include "udis86.h"
 
+
 static ud_t sUDState;
 static addr_t sCurrentReadAddress;
 static void (*sSyntax)(ud_t *) = UD_SYN_ATT;
@@ -29,6 +30,18 @@ read_next_byte(struct ud*)
 }
 
 
+static void
+setup_disassembler(addr_t where)
+{
+	ud_set_input_hook(&sUDState, &read_next_byte);
+	sCurrentReadAddress	= where;
+	ud_set_mode(&sUDState, 32);
+	ud_set_pc(&sUDState, (uint64_t)where);
+	ud_set_syntax(&sUDState, sSyntax);
+	ud_set_vendor(&sUDState, sVendor);
+}
+
+
 extern "C" void
 disasm_arch_assert(const char *condition)
 {
@@ -37,27 +50,54 @@ disasm_arch_assert(const char *condition)
 
 
 status_t
-disasm_arch_dump_insns(addr_t where, int count)
+disasm_arch_dump_insns(addr_t where, int count, addr_t baseAddress,
+	int backCount)
 {
-	//status_t err;
-	int i;
+	int skipCount = 0;
 
-	ud_set_input_hook(&sUDState, &read_next_byte);
-	sCurrentReadAddress	= where;
-	ud_set_mode(&sUDState, 32);
-	ud_set_pc(&sUDState, (uint64_t)where);
-	ud_set_syntax(&sUDState, sSyntax);
-	ud_set_vendor(&sUDState, sVendor);
-	for (i = 0; i < count; i++) {
+	if (backCount > 0) {
+		// count the instructions from base address to start address
+		setup_disassembler(baseAddress);
+		addr_t address = baseAddress;
+		int baseCount = 0;
+		int len;
+		while (address < where && (len = ud_disassemble(&sUDState)) >= 1) {
+			address += len;
+			baseCount++;
+		}
+
+		if (address == where) {
+			if (baseCount > backCount)
+				skipCount = baseCount - backCount;
+			count += baseCount;
+		} else
+			baseAddress = where;
+	} else
+		baseAddress = where;
+
+	setup_disassembler(baseAddress);
+
+	for (int i = 0; i < count; i++) {
 		int ret;
 		ret = ud_disassemble(&sUDState);
 		if (ret < 1)
 			break;
+
+		if (skipCount > 0) {
+			skipCount--;
+			continue;
+		}
+
+		addr_t address = (addr_t)ud_insn_off(&sUDState);
+		if (address == where)
+			kprintf("\x1b[34m");
+
 		// TODO: dig operands and lookup symbols
-		kprintf("0x%08lx: %16.16s\t%s\n",
-			(uint32)(/*where +*/ ud_insn_off(&sUDState)),
-			ud_insn_hex(&sUDState),
+		kprintf("0x%08lx: %16.16s\t%s\n", address, ud_insn_hex(&sUDState),
 			ud_insn_asm(&sUDState));
+
+		if (address == where)
+			kprintf("\x1b[m");
 	}
 	return B_OK;
 }