[pxe] Remove userptr_t from PXE API call dispatcher

Simplify the PXE API call dispatcher code by assuming that the PXE
parameter block is accessible via a direct pointer dereference.  This
avoids the need for the API call dispatcher to know the size of the
parameter block.

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

Author: mcb30

src/arch/x86/include/pxe.h

@@ -85,8 +85,6 @@ struct pxe_api_call {
 	 * @ret exit		PXE API call exit code
 	 */
 	PXENV_EXIT_t ( * entry ) ( union u_PXENV_ANY *params );
-	/** Length of parameters */
-	uint16_t params_len;
 	/** Opcode */
 	uint16_t opcode;
 };
@@ -112,7 +110,6 @@ struct pxe_api_call {
 			 ( union u_PXENV_ANY *params ) ) _entry )	      \
 		   : ( ( PXENV_EXIT_t ( * )				      \
 			 ( union u_PXENV_ANY *params ) ) _entry ) ),	      \
-	.params_len = sizeof ( _params_type ),				      \
 	.opcode = _opcode,						      \
 	}
 

src/arch/x86/interface/pxe/pxe_call.c

@@ -144,10 +144,10 @@ static struct profiler * pxe_api_profiler ( unsigned int opcode ) {
  */
 __asmcall void pxe_api_call ( struct i386_all_regs *ix86 ) {
 	uint16_t opcode = ix86->regs.bx;
-	userptr_t uparams = real_to_virt ( ix86->segs.es, ix86->regs.di );
 	struct profiler *profiler = pxe_api_profiler ( opcode );
+	union u_PXENV_ANY *params =
+		real_to_virt ( ix86->segs.es, ix86->regs.di );
 	struct pxe_api_call *call;
-	union u_PXENV_ANY params;
 	PXENV_EXIT_t ret;
 
 	/* Start profiling */
@@ -160,17 +160,13 @@ __asmcall void pxe_api_call ( struct i386_all_regs *ix86 ) {
 		call = &pxenv_unknown_api;
 	}
 
-	/* Copy parameter block from caller */
-	copy_from_user ( &params, uparams, 0, call->params_len );
-
 	/* Set default status in case child routine fails to do so */
-	params.Status = PXENV_STATUS_FAILURE;
+	params->Status = PXENV_STATUS_FAILURE;
 
 	/* Hand off to relevant API routine */
-	ret = call->entry ( &params );
+	ret = call->entry ( params );
 
-	/* Copy modified parameter block back to caller and return */
-	copy_to_user ( uparams, 0, &params, call->params_len );
+	/* Return exit code in %ax */
 	ix86->regs.ax = ret;
 
 	/* Stop profiling, if applicable */
@@ -195,24 +191,20 @@ int pxe_api_call_weak ( struct i386_all_regs *ix86 ) {
  * @ret ax		PXE exit code
  */
 __asmcall void pxe_loader_call ( struct i386_all_regs *ix86 ) {
-	userptr_t uparams = real_to_virt ( ix86->segs.es, ix86->regs.di );
-	struct s_UNDI_LOADER params;
+	struct s_UNDI_LOADER *params =
+		real_to_virt ( ix86->segs.es, ix86->regs.di );
 	PXENV_EXIT_t ret;
 
-	/* Copy parameter block from caller */
-	copy_from_user ( &params, uparams, 0, sizeof ( params ) );
-
 	/* Fill in ROM segment address */
 	ppxe.UNDIROMID.segment = ix86->segs.ds;
 
 	/* Set default status in case child routine fails to do so */
-	params.Status = PXENV_STATUS_FAILURE;
+	params->Status = PXENV_STATUS_FAILURE;
 
 	/* Call UNDI loader */
-	ret = undi_loader ( &params );
+	ret = undi_loader ( params );
 
-	/* Copy modified parameter block back to caller and return */
-	copy_to_user ( uparams, 0, &params, sizeof ( params ) );
+	/* Return exit code in %ax */
 	ix86->regs.ax = ret;
 }