Commit 28213cb6 authored by Igor Mammedov's avatar Igor Mammedov Committed by Michael S. Tsirkin
Browse files

acpi: make bios_linker_loader_add_checksum() API offset based 



It should help to make clear that bios_linker works in terms
of offsets within a file. Also it should prevent mistakes
where user passes as arguments pointers to unrelated to file blobs.

While at it, considering that it's a ACPI checksum and
it's initial value must be 0, move checksum field zeroing
into bios_linker_loader_add_checksum() instead of doing it
at every call site manually before bios_linker_loader_add_checksum()
is called.

In addition add extra boundary checks.

Signed-off-by: default avatarIgor Mammedov <imammedo@redhat.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 4678124b

hw/acpi/aml-build.c

+3 −2
Original line number Diff line number Diff line
@@ -1493,6 +1493,8 @@ build_header(BIOSLinker *linker, GArray *table_data, 
             AcpiTableHeader *h, const char *sig, int len, uint8_t rev,

             const char *oem_id, const char *oem_table_id)

{

    unsigned tbl_offset = (char *)h - table_data->data;

    unsigned checksum_offset = (char *)&h->checksum - table_data->data;

    memcpy(&h->signature, sig, 4);

    h->length = cpu_to_le32(len);

    h->revision = rev;
@@ -1513,10 +1515,9 @@ build_header(BIOSLinker *linker, GArray *table_data, 
    h->oem_revision = cpu_to_le32(1);

    memcpy(h->asl_compiler_id, ACPI_BUILD_APPNAME4, 4);

    h->asl_compiler_revision = cpu_to_le32(1);

    h->checksum = 0;

    /* Checksum to be filled in by Guest linker */

    bios_linker_loader_add_checksum(linker, ACPI_BUILD_TABLE_FILE,

                                    h, len, &h->checksum);

        tbl_offset, len, checksum_offset);

}



void *acpi_data_push(GArray *table_data, unsigned size)

hw/acpi/bios-linker-loader.c

+13 −23
Original line number Diff line number Diff line
@@ -189,8 +189,8 @@ void bios_linker_loader_alloc(BIOSLinker *linker, 
}



/*

 * bios_linker_loader_add_checksum: ask guest to add checksum of file data

 * into (same) file at the specified pointer.

 * bios_linker_loader_add_checksum: ask guest to add checksum of ACPI

 * table in the specified file at the specified offset.

 *

 * Checksum calculation simply sums -X for each byte X in the range

 * using 8-bit math (i.e. ACPI checksum).
@@ -198,35 +198,25 @@ void bios_linker_loader_alloc(BIOSLinker *linker, 
 * @linker: linker object instance

 * @file: file that includes the checksum to be calculated

 *        and the data to be checksummed

 * @start, @size: range of data to checksum

 * @checksum: location of the checksum to be patched within file blob

 *

 * Notes:

 * - checksum byte initial value must have been pushed into blob

 *   associated with @file and reside at address @checksum.

 * - @size bytes must have been pushed into blob associated wtih @file

 *   and reside at address @start.

 * - Guest calculates checksum of specified range of data, result is added to

 *   initial value at @checksum into copy of @file in Guest memory.

 * - Range might include the checksum itself.

 * - To avoid confusion, caller must always put 0x0 at @checksum.

 * - @file must be loaded into Guest memory using bios_linker_loader_alloc

 * @start_offset, @size: range of data in the file to checksum,

 *                       relative to the start of file blob

 * @checksum_offset: location of the checksum to be patched within file blob,

 *                   relative to the start of file blob

 */

void bios_linker_loader_add_checksum(BIOSLinker *linker, const char *file_name,

                                     void *start, unsigned size,

                                     uint8_t *checksum)

                                     unsigned start_offset, unsigned size,

                                     unsigned checksum_offset)

{

    BiosLinkerLoaderEntry entry;

    const BiosLinkerFileEntry *file = bios_linker_find_file(linker, file_name);

    ptrdiff_t checksum_offset = (gchar *)checksum - file->blob->data;

    ptrdiff_t start_offset = (gchar *)start - file->blob->data;



    assert(checksum_offset >= 0);

    assert(start_offset >= 0);

    assert(checksum_offset + 1 <= file->blob->len);

    assert(file);

    assert(start_offset < file->blob->len);

    assert(start_offset + size <= file->blob->len);

    assert(*checksum == 0x0);

    assert(checksum_offset >= start_offset);

    assert(checksum_offset + 1 <= start_offset + size);



    *(file->blob->data + checksum_offset) = 0;

    memset(&entry, 0, sizeof entry);

    strncpy(entry.cksum.file, file_name, sizeof entry.cksum.file - 1);

    entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM);

hw/arm/virt-acpi-build.c

+2 −3
Original line number Diff line number Diff line
@@ -374,11 +374,10 @@ build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned rsdt_tbl_offset) 
        ACPI_BUILD_RSDP_FILE, rsdt_pa_offset, rsdt_pa_size,

        ACPI_BUILD_TABLE_FILE, rsdt_tbl_offset);



    rsdp->checksum = 0;

    /* Checksum to be filled by Guest linker */

    bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE,

                                    rsdp, sizeof *rsdp,

                                    &rsdp->checksum);

        (char *)rsdp - rsdp_table->data, sizeof *rsdp,

        (char *)&rsdp->checksum - rsdp_table->data);



    return rsdp_table;

}

hw/i386/acpi-build.c

+2 −3
Original line number Diff line number Diff line
@@ -2458,11 +2458,10 @@ build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned rsdt_tbl_offset) 
        ACPI_BUILD_RSDP_FILE, rsdt_pa_offset, rsdt_pa_size,

        ACPI_BUILD_TABLE_FILE, rsdt_tbl_offset);



    rsdp->checksum = 0;

    /* Checksum to be filled by Guest linker */

    bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE,

                                    rsdp, sizeof *rsdp,

                                    &rsdp->checksum);

        (char *)rsdp - rsdp_table->data, sizeof *rsdp,

        (char *)&rsdp->checksum - rsdp_table->data);



    return rsdp_table;

}

include/hw/acpi/bios-linker-loader.h

+2 −2
Original line number Diff line number Diff line
@@ -17,8 +17,8 @@ void bios_linker_loader_alloc(BIOSLinker *linker, 
                              bool alloc_fseg);



void bios_linker_loader_add_checksum(BIOSLinker *linker, const char *file,

                                     void *start, unsigned size,

                                     uint8_t *checksum);

                                     unsigned start_offset, unsigned size,

                                     unsigned checksum_offset);



void bios_linker_loader_add_pointer(BIOSLinker *linker,

                                    const char *dest_file,