efi_umalloc.c File Reference

gPXE user memory allocation API for EFI More...

#include <assert.h>
#include <gpxe/umalloc.h>
#include <gpxe/efi/efi.h>

Go to the source code of this file.

Defines
#define	UNOWHERE   ( ~UNULL )
	Equivalent of NOWHERE for user pointers.
Functions
	FILE_LICENCE (GPL2_OR_LATER)
static userptr_t	efi_urealloc (userptr_t old_ptr, size_t new_size)
	Reallocate external memory.
	PROVIDE_UMALLOC (efi, urealloc, efi_urealloc)

---

Detailed Description

gPXE user memory allocation API for EFI

Definition in file efi_umalloc.c.

---

Define Documentation

#define UNOWHERE   ( ~UNULL )

Equivalent of NOWHERE for user pointers.

Definition at line 32 of file efi_umalloc.c.

Referenced by efi_urealloc(), and memtop_urealloc().

---

Function Documentation

FILE_LICENCE

(

GPL2_OR_LATER

)

static userptr_t efi_urealloc	(	userptr_t	old_ptr,
		size_t	new_size
	)			[static]

Reallocate external memory.

Parameters:

	old_ptr	Memory previously allocated by umalloc(), or UNULL
	new_size	Requested size

Return values:

new_ptr

Allocated memory, or UNULL

Calling realloc() with a new size of zero is a valid way to free a memory block.

Definition at line 44 of file efi_umalloc.c.

References AllocateAnyPages, EFI_BOOT_SERVICES::AllocatePages, assert, _EFI_SYSTEM_TABLE::BootServices, copy_from_user(), copy_to_user(), DBG, EFI_PAGE_SIZE, EFI_SIZE_TO_PAGES, efi_strerror(), efi_systab, EfiBootServicesData, EFI_BOOT_SERVICES::FreePages, memcpy_user(), phys_to_user(), UNOWHERE, UNULL, and user_to_phys().

                                                                     {
        EFI_BOOT_SERVICES *bs = efi_systab->BootServices;
        EFI_PHYSICAL_ADDRESS phys_addr;
        unsigned int new_pages, old_pages;
        userptr_t new_ptr = UNOWHERE;
        size_t old_size;
        EFI_STATUS efirc;

        /* Allocate new memory if necessary.  If allocation fails,
         * return without touching the old block.
         */
        if ( new_size ) {
                new_pages = ( EFI_SIZE_TO_PAGES ( new_size ) + 1 );
                if ( ( efirc = bs->AllocatePages ( AllocateAnyPages,
                                                   EfiBootServicesData,
                                                   new_pages,
                                                   &phys_addr ) ) != 0 ) {
                        DBG ( "EFI could not allocate %d pages: %s\n",
                              new_pages, efi_strerror ( efirc ) );
                        return UNULL;
                }
                assert ( phys_addr != 0 );
                new_ptr = phys_to_user ( phys_addr + EFI_PAGE_SIZE );
                copy_to_user ( new_ptr, -EFI_PAGE_SIZE,
                               &new_size, sizeof ( new_size ) );
                DBG ( "EFI allocated %d pages at %llx\n",
                      new_pages, phys_addr );
        }

        /* Copy across relevant part of the old data region (if any),
         * then free it.  Note that at this point either (a) new_ptr
         * is valid, or (b) new_size is 0; either way, the memcpy() is
         * valid.
         */
        if ( old_ptr && ( old_ptr != UNOWHERE ) ) {
                copy_from_user ( &old_size, old_ptr, -EFI_PAGE_SIZE,
                                 sizeof ( old_size ) );
                memcpy_user ( new_ptr, 0, old_ptr, 0,
                              ( (old_size < new_size) ? old_size : new_size ));
                old_pages = ( EFI_SIZE_TO_PAGES ( old_size ) + 1 );
                phys_addr = user_to_phys ( old_ptr, -EFI_PAGE_SIZE );
                if ( ( efirc = bs->FreePages ( phys_addr, old_pages ) ) != 0 ){
                        DBG ( "EFI could not free %d pages at %llx: %s\n",
                              old_pages, phys_addr, efi_strerror ( efirc ) );
                        /* Not fatal; we have leaked memory but successfully
                         * allocated (if asked to do so).
                         */
                }
                DBG ( "EFI freed %d pages at %llx\n", old_pages, phys_addr );
        }

        return new_ptr;
}

PROVIDE_UMALLOC	(	efi	,
		urealloc	,
		efi_urealloc
	)