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[int13] Test correct return status from INT 13 calls 

INT 13 calls return a status value via %ah, with CF set if %ah is
non-zero (indicating an error).  Our wrappers zero the whole of %ax if
CF is clear, to allow C code (which has no easy access to CF) to
simply test for a non-zero status to detect an error.

The current code assigns the returned status to a uint8_t, effectively
testing %al rather than %ah.  Fix by treating the returned status as a
uint16_t instead.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/58/merge
Michael Brown 2017-01-26 09:45:19 +00:00
parent fcf7751565
commit f8cf3ceb0b
1 changed files with 5 additions and 5 deletions
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10
src/arch/x86/interface/pcbios/int13.c
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@ -1751,7 +1751,7 @@ static void int13_unhook ( unsigned int drive ) {
* @ret rc Return status code * @ret rc Return status code
*/ */
static int int13_load_mbr ( unsigned int drive, struct segoff *address ) { static int int13_load_mbr ( unsigned int drive, struct segoff *address ) {
uint8_t status; uint16_t status;
int discard_b, discard_c, discard_d; int discard_b, discard_c, discard_d;
uint16_t magic; uint16_t magic;
@ -1775,7 +1775,7 @@ static int int13_load_mbr ( unsigned int drive, struct segoff *address ) {
: "a" ( 0x0201 ), "b" ( *address ), : "a" ( 0x0201 ), "b" ( *address ),
"c" ( 1 ), "d" ( drive ) ); "c" ( 1 ), "d" ( drive ) );
if ( status ) { if ( status ) {
DBG ( "INT13 drive %02x could not read MBR (status %02x)\n", DBG ( "INT13 drive %02x could not read MBR (status %04x)\n",
drive, status ); drive, status );
return -EIO; return -EIO;
} }
@ -1818,7 +1818,7 @@ static int int13_load_eltorito ( unsigned int drive, struct segoff *address ) {
struct eltorito_validation_entry valid; struct eltorito_validation_entry valid;
struct eltorito_boot_entry boot; struct eltorito_boot_entry boot;
} __attribute__ (( packed )) catalog; } __attribute__ (( packed )) catalog;
uint8_t status; uint16_t status;
/* Use INT 13, 4d to read the boot catalog */ /* Use INT 13, 4d to read the boot catalog */
__asm__ __volatile__ ( REAL_CODE ( "stc\n\t" __asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
@ -1833,7 +1833,7 @@ static int int13_load_eltorito ( unsigned int drive, struct segoff *address ) {
"S" ( __from_data16 ( &eltorito_cmd ) ) ); "S" ( __from_data16 ( &eltorito_cmd ) ) );
if ( status ) { if ( status ) {
DBG ( "INT13 drive %02x could not read El Torito boot catalog " DBG ( "INT13 drive %02x could not read El Torito boot catalog "
"(status %02x)\n", drive, status ); "(status %04x)\n", drive, status );
return -EIO; return -EIO;
} }
copy_from_user ( &catalog, phys_to_user ( eltorito_cmd.buffer ), 0, copy_from_user ( &catalog, phys_to_user ( eltorito_cmd.buffer ), 0,
@ -1880,7 +1880,7 @@ static int int13_load_eltorito ( unsigned int drive, struct segoff *address ) {
"S" ( __from_data16 ( &eltorito_address ) ) ); "S" ( __from_data16 ( &eltorito_address ) ) );
if ( status ) { if ( status ) {
DBG ( "INT13 drive %02x could not read El Torito boot image " DBG ( "INT13 drive %02x could not read El Torito boot image "
"(status %02x)\n", drive, status ); "(status %04x)\n", drive, status );
return -EIO; return -EIO;
} }