[bios] Make uses of REAL_CODE() and PHYS_CODE() 64-bit clean

On a 64-bit CPU, any modification of a register by 32-bit or 16-bit
code will destroy the invisible upper 32 bits of the corresponding
64-bit register.  For example: a 32-bit "pushl %eax" followed by a
"popl %eax" will zero the upper half of %rax.  This differs from the
treatment of upper halves of 32-bit registers by 16-bit code: a
"pushw %ax" followed by a "popw %ax" will leave the upper 16 bits of
%eax unmodified.

Inline assembly generated using REAL_CODE() or PHYS_CODE() will
therefore have to preserve the upper halves of all registers, to avoid
clobbering registers that gcc expects to be preserved.

Output operands from REAL_CODE() and PHYS_CODE() assembly may
therefore contain undefined values in the upper 32 bits.

Fix by using explicit variable widths (e.g. uint32_t) for
non-discarded output operands, to ensure that undefined values in the
upper 32 bits of 64-bit registers are ignored.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

5 files changed, 17 insertions, 13 deletions

diff --git a/src/arch/x86/image/nbi.c b/src/arch/x86/image/nbi.c
index 9904614..b691bee 100644
--- a/src/arch/x86/image/nbi.c
+++ b/src/arch/x86/image/nbi.c
@@ -241,7 +241,7 @@ static int nbi_process_segments ( struct image *image,
  */
 static int nbi_boot16 ( struct image *image, struct imgheader *imgheader ) {
 	int discard_D, discard_S, discard_b;
-	int rc;
+	int32_t rc;
 
 	DBGC ( image, "NBI %p executing 16-bit image at %04x:%04x\n", image,
 	       imgheader->execaddr.segoff.segment,
@@ -283,7 +283,7 @@ static int nbi_boot32 ( struct image *image, struct imgheader *imgheader ) {
 		0
 	};
 	int discard_D, discard_S, discard_b;
-	int rc;
+	int32_t rc;
 
 	DBGC ( image, "NBI %p executing 32-bit image at %lx\n",
 	       image, imgheader->execaddr.linear );
diff --git a/src/arch/x86/interface/pcbios/memmap.c b/src/arch/x86/interface/pcbios/memmap.c
index 88bfec9..daae382 100644
--- a/src/arch/x86/interface/pcbios/memmap.c
+++ b/src/arch/x86/interface/pcbios/memmap.c
@@ -174,7 +174,7 @@ static int meme820 ( struct memory_map *memmap ) {
 	struct memory_region *prev_region = NULL;
 	uint32_t next = 0;
 	uint32_t smap;
-	size_t size;
+	uint32_t size;
 	unsigned int flags;
 	unsigned int discard_D;
 
@@ -216,7 +216,7 @@ static int meme820 ( struct memory_map *memmap ) {
 		}
 
 		if ( size < E820_MIN_SIZE ) {
-			DBG ( "INT 15,e820 returned only %zd bytes\n", size );
+			DBG ( "INT 15,e820 returned only %d bytes\n", size );
 			return -EINVAL;
 		}
 
diff --git a/src/arch/x86/interface/pcbios/pcibios.c b/src/arch/x86/interface/pcbios/pcibios.c
index 34efa0b..07ac0c1 100644
--- a/src/arch/x86/interface/pcbios/pcibios.c
+++ b/src/arch/x86/interface/pcbios/pcibios.c
@@ -70,7 +70,7 @@ static int pcibios_num_bus ( void ) {
  */
 int pcibios_read ( struct pci_device *pci, uint32_t command, uint32_t *value ){
 	int discard_b, discard_D;
-	int status;
+	uint16_t status;
 
 	__asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
 					   "int $0x1a\n\t"
@@ -85,7 +85,7 @@ int pcibios_read ( struct pci_device *pci, uint32_t command, uint32_t *value ){
 				 "b" ( pci->busdevfn )
 			       : "edx" );
 
-	return ( ( status >> 8 ) & 0xff );
+	return ( status >> 8 );
 }
 
 /**
@@ -98,7 +98,7 @@ int pcibios_read ( struct pci_device *pci, uint32_t command, uint32_t *value ){
  */
 int pcibios_write ( struct pci_device *pci, uint32_t command, uint32_t value ){
 	int discard_b, discard_c, discard_D;
-	int status;
+	uint16_t status;
 
 	__asm__ __volatile__ ( REAL_CODE ( "stc\n\t"
 					   "int $0x1a\n\t"
@@ -111,7 +111,7 @@ int pcibios_write ( struct pci_device *pci, uint32_t command, uint32_t value ){
 			         "b" ( pci->busdevfn ), "c" ( value )
 			       : "edx" );
 	
-	return ( ( status >> 8 ) & 0xff );
+	return ( status >> 8 );
 }
 
 PROVIDE_PCIAPI ( pcbios, pci_num_bus, pcibios_num_bus );
diff --git a/src/arch/x86/interface/pcbios/rtc_entropy.c b/src/arch/x86/interface/pcbios/rtc_entropy.c
index 6e7ac83..83c2445 100644
--- a/src/arch/x86/interface/pcbios/rtc_entropy.c
+++ b/src/arch/x86/interface/pcbios/rtc_entropy.c
@@ -187,7 +187,7 @@ uint8_t rtc_sample ( void ) {
 			    /* Disable interrupts */
 			    "cli\n\t"
 			    )
-		: "=a" ( after ), "=d" ( before ), "=q" ( temp )
+		: "=a" ( after ), "=d" ( before ), "=Q" ( temp )
 		: "2" ( 0 ) );
 
 	return ( after - before );
diff --git a/src/arch/x86/interface/pxeparent/pxeparent.c b/src/arch/x86/interface/pxeparent/pxeparent.c
index 0b6be9a..cc6101c 100644
--- a/src/arch/x86/interface/pxeparent/pxeparent.c
+++ b/src/arch/x86/interface/pxeparent/pxeparent.c
@@ -208,8 +208,10 @@ int pxeparent_call ( SEGOFF16_t entry, unsigned int function,
 		     void *params, size_t params_len ) {
 	struct pxeparent_profiler *profiler = pxeparent_profiler ( function );
 	PXENV_EXIT_t exit;
-	unsigned long started;
-	unsigned long stopped;
+	uint32_t before;
+	uint32_t started;
+	uint32_t stopped;
+	uint32_t after;
 	int discard_D;
 	int rc;
 
@@ -240,12 +242,14 @@ int pxeparent_call ( SEGOFF16_t entry, unsigned int function,
 			         "D" ( __from_data16 ( &pxeparent_params ) )
 			       : "ecx", "esi" );
 	profile_stop ( &profiler->total );
-	profile_start_at ( &profiler->p2r, profile_started ( &profiler->total));
+	before = profile_started ( &profiler->total );
+	after = profile_stopped ( &profiler->total );
+	profile_start_at ( &profiler->p2r, before );
 	profile_stop_at ( &profiler->p2r, started );
 	profile_start_at ( &profiler->ext, started );
 	profile_stop_at ( &profiler->ext, stopped );
 	profile_start_at ( &profiler->r2p, stopped );
-	profile_stop_at ( &profiler->r2p, profile_stopped ( &profiler->total ));
+	profile_stop_at ( &profiler->r2p, after );
 
 	/* Determine return status code based on PXENV_EXIT and
 	 * PXENV_STATUS