loader: Implement .hex file loader

This patch adds Intel Hexadecimal Object File format support to the
generic loader device.  The file format specification is available here:
http://www.piclist.com/techref/fileext/hex/intel.htm

This file format is often used with microcontrollers such as the
micro:bit, Arduino, STM32, etc.  Users expect to be able to run .hex
files directly with without first converting them to ELF.  Most
micro:bit code is developed in web-based IDEs without direct user access
to binutils so it is important for QEMU to handle this file format
natively.

Signed-off-by: Su Hang <suhang16@mails.ucas.ac.cn>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20180814162739.11814-6-stefanha@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/core/generic-loader.c

@@ -147,6 +147,10 @@ static void generic_loader_realize(DeviceState *dev, Error **errp)
                 size = load_uimage_as(s->file, &entry, NULL, NULL, NULL, NULL,
                                       as);
             }
+
+            if (size < 0) {
+                size = load_targphys_hex_as(s->file, &entry, as);
+            }
         }
 
         if (size < 0 || s->force_raw) {

hw/core/loader.c

@@ -1321,3 +1321,252 @@ void hmp_info_roms(Monitor *mon, const QDict *qdict)
         }
     }
 }
+
+typedef enum HexRecord HexRecord;
+enum HexRecord {
+    DATA_RECORD = 0,
+    EOF_RECORD,
+    EXT_SEG_ADDR_RECORD,
+    START_SEG_ADDR_RECORD,
+    EXT_LINEAR_ADDR_RECORD,
+    START_LINEAR_ADDR_RECORD,
+};
+
+/* Each record contains a 16-bit address which is combined with the upper 16
+ * bits of the implicit "next address" to form a 32-bit address.
+ */
+#define NEXT_ADDR_MASK 0xffff0000
+
+#define DATA_FIELD_MAX_LEN 0xff
+#define LEN_EXCEPT_DATA 0x5
+/* 0x5 = sizeof(byte_count) + sizeof(address) + sizeof(record_type) +
+ *       sizeof(checksum) */
+typedef struct {
+    uint8_t byte_count;
+    uint16_t address;
+    uint8_t record_type;
+    uint8_t data[DATA_FIELD_MAX_LEN];
+    uint8_t checksum;
+} HexLine;
+
+/* return 0 or -1 if error */
+static bool parse_record(HexLine *line, uint8_t *our_checksum, const uint8_t c,
+                         uint32_t *index, const bool in_process)
+{
+    /* +-------+---------------+-------+---------------------+--------+
+     * | byte  |               |record |                     |        |
+     * | count |    address    | type  |        data         |checksum|
+     * +-------+---------------+-------+---------------------+--------+
+     * ^       ^               ^       ^                     ^        ^
+     * |1 byte |    2 bytes    |1 byte |     0-255 bytes     | 1 byte |
+     */
+    uint8_t value = 0;
+    uint32_t idx = *index;
+    /* ignore space */
+    if (g_ascii_isspace(c)) {
+        return true;
+    }
+    if (!g_ascii_isxdigit(c) || !in_process) {
+        return false;
+    }
+    value = g_ascii_xdigit_value(c);
+    value = (idx & 0x1) ? (value & 0xf) : (value << 4);
+    if (idx < 2) {
+        line->byte_count |= value;
+    } else if (2 <= idx && idx < 6) {
+        line->address <<= 4;
+        line->address += g_ascii_xdigit_value(c);
+    } else if (6 <= idx && idx < 8) {
+        line->record_type |= value;
+    } else if (8 <= idx && idx < 8 + 2 * line->byte_count) {
+        line->data[(idx - 8) >> 1] |= value;
+    } else if (8 + 2 * line->byte_count <= idx &&
+               idx < 10 + 2 * line->byte_count) {
+        line->checksum |= value;
+    } else {
+        return false;
+    }
+    *our_checksum += value;
+    ++(*index);
+    return true;
+}
+
+typedef struct {
+    const char *filename;
+    HexLine line;
+    uint8_t *bin_buf;
+    hwaddr *start_addr;
+    int total_size;
+    uint32_t next_address_to_write;
+    uint32_t current_address;
+    uint32_t current_rom_index;
+    uint32_t rom_start_address;
+    AddressSpace *as;
+} HexParser;
+
+/* return size or -1 if error */
+static int handle_record_type(HexParser *parser)
+{
+    HexLine *line = &(parser->line);
+    switch (line->record_type) {
+    case DATA_RECORD:
+        parser->current_address =
+            (parser->next_address_to_write & NEXT_ADDR_MASK) | line->address;
+        /* verify this is a contiguous block of memory */
+        if (parser->current_address != parser->next_address_to_write) {
+            if (parser->current_rom_index != 0) {
+                rom_add_blob_fixed_as(parser->filename, parser->bin_buf,
+                                      parser->current_rom_index,
+                                      parser->rom_start_address, parser->as);
+            }
+            parser->rom_start_address = parser->current_address;
+            parser->current_rom_index = 0;
+        }
+
+        /* copy from line buffer to output bin_buf */
+        memcpy(parser->bin_buf + parser->current_rom_index, line->data,
+               line->byte_count);
+        parser->current_rom_index += line->byte_count;
+        parser->total_size += line->byte_count;
+        /* save next address to write */
+        parser->next_address_to_write =
+            parser->current_address + line->byte_count;
+        break;
+
+    case EOF_RECORD:
+        if (parser->current_rom_index != 0) {
+            rom_add_blob_fixed_as(parser->filename, parser->bin_buf,
+                                  parser->current_rom_index,
+                                  parser->rom_start_address, parser->as);
+        }
+        return parser->total_size;
+    case EXT_SEG_ADDR_RECORD:
+    case EXT_LINEAR_ADDR_RECORD:
+        if (line->byte_count != 2 && line->address != 0) {
+            return -1;
+        }
+
+        if (parser->current_rom_index != 0) {
+            rom_add_blob_fixed_as(parser->filename, parser->bin_buf,
+                                  parser->current_rom_index,
+                                  parser->rom_start_address, parser->as);
+        }
+
+        /* save next address to write,
+         * in case of non-contiguous block of memory */
+        parser->next_address_to_write = (line->data[0] << 12) |
+                                        (line->data[1] << 4);
+        if (line->record_type == EXT_LINEAR_ADDR_RECORD) {
+            parser->next_address_to_write <<= 12;
+        }
+
+        parser->rom_start_address = parser->next_address_to_write;
+        parser->current_rom_index = 0;
+        break;
+
+    case START_SEG_ADDR_RECORD:
+        if (line->byte_count != 4 && line->address != 0) {
+            return -1;
+        }
+
+        /* x86 16-bit CS:IP segmented addressing */
+        *(parser->start_addr) = (((line->data[0] << 8) | line->data[1]) << 4) +
+                                ((line->data[2] << 8) | line->data[3]);
+        break;
+
+    case START_LINEAR_ADDR_RECORD:
+        if (line->byte_count != 4 && line->address != 0) {
+            return -1;
+        }
+
+        *(parser->start_addr) = ldl_be_p(line->data);
+        break;
+
+    default:
+        return -1;
+    }
+
+    return parser->total_size;
+}
+
+/* return size or -1 if error */
+static int parse_hex_blob(const char *filename, hwaddr *addr, uint8_t *hex_blob,
+                          size_t hex_blob_size, AddressSpace *as)
+{
+    bool in_process = false; /* avoid re-enter and
+                              * check whether record begin with ':' */
+    uint8_t *end = hex_blob + hex_blob_size;
+    uint8_t our_checksum = 0;
+    uint32_t record_index = 0;
+    HexParser parser = {
+        .filename = filename,
+        .bin_buf = g_malloc(hex_blob_size),
+        .start_addr = addr,
+        .as = as,
+    };
+
+    rom_transaction_begin();
+
+    for (; hex_blob < end; ++hex_blob) {
+        switch (*hex_blob) {
+        case '\r':
+        case '\n':
+            if (!in_process) {
+                break;
+            }
+
+            in_process = false;
+            if ((LEN_EXCEPT_DATA + parser.line.byte_count) * 2 !=
+                    record_index ||
+                our_checksum != 0) {
+                parser.total_size = -1;
+                goto out;
+            }
+
+            if (handle_record_type(&parser) == -1) {
+                parser.total_size = -1;
+                goto out;
+            }
+            break;
+
+        /* start of a new record. */
+        case ':':
+            memset(&parser.line, 0, sizeof(HexLine));
+            in_process = true;
+            record_index = 0;
+            break;
+
+        /* decoding lines */
+        default:
+            if (!parse_record(&parser.line, &our_checksum, *hex_blob,
+                              &record_index, in_process)) {
+                parser.total_size = -1;
+                goto out;
+            }
+            break;
+        }
+    }
+
+out:
+    g_free(parser.bin_buf);
+    rom_transaction_end(parser.total_size != -1);
+    return parser.total_size;
+}
+
+/* return size or -1 if error */
+int load_targphys_hex_as(const char *filename, hwaddr *entry, AddressSpace *as)
+{
+    gsize hex_blob_size;
+    gchar *hex_blob;
+    int total_size = 0;
+
+    if (!g_file_get_contents(filename, &hex_blob, &hex_blob_size, NULL)) {
+        return -1;
+    }
+
+    total_size = parse_hex_blob(filename, entry, (uint8_t *)hex_blob,
+                                hex_blob_size, as);
+
+    g_free(hex_blob);
+    return total_size;
+}

include/hw/loader.h

@@ -28,6 +28,18 @@ ssize_t load_image_size(const char *filename, void *addr, size_t size);
 int load_image_targphys_as(const char *filename,
                            hwaddr addr, uint64_t max_sz, AddressSpace *as);
 
+/**load_targphys_hex_as:
+ * @filename: Path to the .hex file
+ * @entry: Store the entry point given by the .hex file
+ * @as: The AddressSpace to load the .hex file to. The value of
+ *      address_space_memory is used if nothing is supplied here.
+ *
+ * Load a fixed .hex file into memory.
+ *
+ * Returns the size of the loaded .hex file on success, -1 otherwise.
+ */
+int load_targphys_hex_as(const char *filename, hwaddr *entry, AddressSpace *as);
+
 /** load_image_targphys:
  * Same as load_image_targphys_as(), but doesn't allow the caller to specify
  * an AddressSpace.