From: Erik van der Kouwe <erikvdk@gmail.com>
Date: Fri, 26 Nov 2010 16:57:29 +0000 (-0600)
Subject: disassemble the code around the RIP. It starts disassembly 64 bytes before and contin... 
X-Git-Url: http://v3vee.org/palacios/gitweb/gitweb.cgi?a=commitdiff_plain;h=7043e3314c5843994dbd6615aca71b0378950b3e;p=palacios.git

disassemble the code around the RIP. It starts disassembly 64 bytes before and continues up to 32 bytes after the RIP
---

diff --git a/palacios/include/palacios/vmm_xed.h b/palacios/include/palacios/vmm_xed.h
index 95e68ec..ef1def2 100644
--- a/palacios/include/palacios/vmm_xed.h
+++ b/palacios/include/palacios/vmm_xed.h
@@ -22,6 +22,7 @@
 
 #ifdef __V3VEE__
 
+int v3_disasm(struct guest_info * info, void *instr_ptr, addr_t * rip, int mark);
 
 #endif // ! __V3VEE__
 
diff --git a/palacios/src/palacios/vm_guest.c b/palacios/src/palacios/vm_guest.c
index cca2359..e9ff5f7 100644
--- a/palacios/src/palacios/vm_guest.c
+++ b/palacios/src/palacios/vm_guest.c
@@ -29,6 +29,7 @@
 #include <palacios/vmm_lowlevel.h>
 #include <palacios/vmm_sprintf.h>
 #include <palacios/vmm_muxer.h>
+#include <palacios/vmm_xed.h>
 
 
 v3_cpu_mode_t v3_get_vm_cpu_mode(struct guest_info * info) {
@@ -257,6 +258,55 @@ void v3_print_ctrl_regs(struct guest_info * info) {
 }
 
 
+static int safe_gva_to_hva(struct guest_info * info, addr_t linear_addr, addr_t * host_addr) {
+    /* select the proper translation based on guest mode */
+    if (info->mem_mode == PHYSICAL_MEM) {
+    	if (v3_gpa_to_hva(info, linear_addr, host_addr) == -1) return -1;
+    } else if (info->mem_mode == VIRTUAL_MEM) {
+	if (v3_gva_to_hva(info, linear_addr, host_addr) == -1) return -1;
+    }
+    return 0;
+}
+
+static int v3_print_disassembly(struct guest_info * info) {
+    int passed_rip = 0;
+    addr_t rip, rip_linear, rip_host;
+
+    /* we don't know where the instructions preceding RIP start, so we just take
+     * a guess and hope the instruction stream synced up with our disassembly
+     * some time before RIP; if it has not we correct RIP at that point
+     */
+
+    /* start disassembly 64 bytes before current RIP, continue 32 bytes after */
+    rip = (addr_t) info->rip - 64;
+    while ((int) (rip - info->rip) < 32) {
+    	/* always print RIP, even if the instructions before were bad */
+    	if (!passed_rip && rip >= info->rip) {
+    	    if (rip != info->rip) {
+    	    	V3_Print("***** bad disassembly up to this point *****\n");
+    	    	rip = info->rip;
+    	    }
+    	    passed_rip = 1;
+    	}
+
+    	/* look up host virtual address for this instruction */
+    	rip_linear = get_addr_linear(info, rip, &(info->segments.cs));
+    	if (safe_gva_to_hva(info, rip_linear, &rip_host) < 0) {
+    	    rip++;
+    	    continue;
+    	}
+
+    	/* print disassembled instrcution (updates rip) */
+    	if (v3_disasm(info, (void *) rip_host, &rip, rip == info->rip) < 0) {
+    	    rip++;
+    	    continue;
+    	}
+    }
+
+    return 0;
+}
+
+
 void v3_print_guest_state(struct guest_info * info) {
     addr_t linear_addr = 0; 
 
@@ -281,6 +331,8 @@ void v3_print_guest_state(struct guest_info * info) {
     v3_print_mem_map(info->vm_info);
 
     v3_print_stack(info);
+
+    v3_print_disassembly(info);
 }
 
 
diff --git a/palacios/src/palacios/vmm_xed.c b/palacios/src/palacios/vmm_xed.c
index bd0d4f0..99ce14e 100644
--- a/palacios/src/palacios/vmm_xed.c
+++ b/palacios/src/palacios/vmm_xed.c
@@ -294,6 +294,55 @@ static int decode_string_op(struct guest_info * info,
 
 
 
+int v3_disasm(struct guest_info * info, void *instr_ptr, addr_t * rip, int mark) {
+    char buffer[256];
+    int i;
+    unsigned length;
+    xed_decoded_inst_t xed_instr;
+    xed_error_enum_t xed_error;
+
+    /* disassemble the specified instruction */
+    if (set_decoder_mode(info, info->decoder_state) == -1) {
+	PrintError("Could not set decoder mode\n");
+	return -1;
+    }
+
+    xed_decoded_inst_zero_set_mode(&xed_instr, info->decoder_state);
+
+    xed_error = xed_decode(&xed_instr, 
+			   REINTERPRET_CAST(const xed_uint8_t *, instr_ptr), 
+			   XED_MAX_INSTRUCTION_BYTES);
+
+    if (xed_error != XED_ERROR_NONE) {
+	PrintError("Xed error: %s\n", xed_error_enum_t2str(xed_error));
+	return -1;
+    }
+
+    /* obtain string representation in AT&T syntax */
+    if (!xed_format_att(&xed_instr, buffer, sizeof(buffer), *rip)) {
+	PrintError("Xed error: cannot disaaemble\n");
+	return -1;
+    }
+
+    /* print address, opcode bytes and the disassembled instruction */
+    length = xed_decoded_inst_get_length(&xed_instr);
+    V3_Print("0x%p %c ", (void *) *rip, mark ? '*' : ' ');
+    for (i = 0; i < length; i++) {
+    	unsigned char b = ((unsigned char *) instr_ptr)[i];
+    	V3_Print("%x%x ", b >> 4, b & 0xf);
+    }
+    while (i++ < 8) {
+    	V3_Print("   ");
+    }
+    V3_Print("%s\n", buffer);
+
+    /* move on to next instruction */
+    *rip += length;
+    return 0;
+}
+
+
+
 int v3_decode(struct guest_info * info, addr_t instr_ptr, struct x86_instr * instr) {
     xed_decoded_inst_t xed_instr;
     xed_error_enum_t xed_error;