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src/core/fdtmem.c
401 строка
11 KB
Michael Brown
[fdtmem] Limit relocation to 32-bit address space
11 июн 2025, 15:49
11 июн 2025, 15:49
3e8909c
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/* * Copyright (C) 2025 Michael Brown <mbrown@fensystems.co.uk>. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License as * published by the Free Software Foundation; either version 2 of the * License, or (at your option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA * 02110-1301, USA. * * You can also choose to distribute this program under the terms of * the Unmodified Binary Distribution Licence (as given in the file * COPYING.UBDL), provided that you have satisfied its requirements. */ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL ); #include <stdint.h> #include <string.h> #include <errno.h> #include <assert.h> #include <byteswap.h> #include <ipxe/uaccess.h> #include <ipxe/memmap.h> #include <ipxe/io.h> #include <ipxe/fdt.h> #include <ipxe/fdtmem.h> /** @file * * Flattened Device Tree memory map * */ /** Start address of the iPXE image */ extern char _prefix[]; /** End address of the iPXE image */ extern char _end[]; /** Total in-memory size (calculated by linker) */ extern size_t ABS_SYMBOL ( _memsz ); static size_t memsz = ABS_VALUE_INIT ( _memsz ); /** Relocation required alignment (defined by prefix or linker) */ extern size_t ABS_SYMBOL ( _max_align ); static size_t max_align = ABS_VALUE_INIT ( _max_align ); /** In-use memory region for iPXE and system device tree copy */ struct used_region fdtmem_used __used_region = { .name = "iPXE/FDT", }; /** Maximum accessible physical address */ static physaddr_t fdtmem_max; /** Maximum 32-bit physical address */ #define FDTMEM_MAX32 0xffffffff /** * Update memory region descriptor based on device tree node * * @v region Memory region of interest to be updated * @v fdt Device tree * @v offset Starting node offset * @v match Required device type (or NULL) * @v flags Region flags * @ret rc Return status code */ static int fdtmem_update_node ( struct memmap_region *region, struct fdt *fdt, unsigned int offset, const char *match, unsigned int flags ) { struct fdt_descriptor desc; struct fdt_reg_cells regs; const char *devtype; uint64_t start; uint64_t size; int depth; int count; int index; int rc; /* Parse region cell sizes */ fdt_reg_cells ( fdt, offset, ®s ); /* Scan through reservations */ for ( depth = -1 ; ; depth += desc.depth, offset = desc.next ) { /* Describe token */ if ( ( rc = fdt_describe ( fdt, offset, &desc ) ) != 0 ) { DBGC ( region, "FDTMEM has malformed node: %s\n", strerror ( rc ) ); return rc; } /* Terminate when we exit this node */ if ( ( depth == 0 ) && ( desc.depth < 0 ) ) break; /* Ignore any non-immediate child nodes */ if ( ! ( ( depth == 0 ) && desc.name && ( ! desc.data ) ) ) continue; /* Ignore any non-matching children */ if ( match ) { devtype = fdt_string ( fdt, desc.offset, "device_type" ); if ( ! devtype ) continue; if ( strcmp ( devtype, match ) != 0 ) continue; } /* Count regions */ count = fdt_reg_count ( fdt, desc.offset, ®s ); if ( count < 0 ) { if ( flags & MEMMAP_FL_RESERVED ) { /* Assume this is a non-fixed reservation */ continue; } rc = count; DBGC ( region, "FDTMEM has malformed region %s: %s\n", desc.name, strerror ( rc ) ); continue; } /* Scan through this region */ for ( index = 0 ; index < count ; index++ ) { /* Get region starting address and size */ if ( ( rc = fdt_reg_address ( fdt, desc.offset, ®s, index, &start ) ) != 0 ){ DBGC ( region, "FDTMEM %s region %d has " "malformed start address: %s\n", desc.name, index, strerror ( rc ) ); break; } if ( ( rc = fdt_reg_size ( fdt, desc.offset, ®s, index, &size ) ) != 0 ) { DBGC ( region, "FDTMEM %s region %d has " "malformed size: %s\n", desc.name, index, strerror ( rc ) ); break; } /* Update memory region descriptor */ memmap_update ( region, start, size, flags, desc.name ); } } return 0; } /** * Update memory region descriptor based on device tree * * @v region Memory region of interest to be updated * @v fdt Device tree * @ret rc Return status code */ static int fdtmem_update_tree ( struct memmap_region *region, struct fdt *fdt ) { const struct fdt_reservation *rsv; unsigned int offset; int rc; /* Update based on memory regions in the root node */ if ( ( rc = fdtmem_update_node ( region, fdt, 0, "memory", MEMMAP_FL_MEMORY ) ) != 0 ) return rc; /* Update based on memory reservations block */ for_each_fdt_reservation ( rsv, fdt ) { memmap_update ( region, be64_to_cpu ( rsv->start ), be64_to_cpu ( rsv->size ), MEMMAP_FL_RESERVED, NULL ); } /* Locate reserved-memory node */ if ( ( rc = fdt_path ( fdt, "/reserved-memory", &offset ) ) != 0 ) { DBGC ( region, "FDTMEM could not locate /reserved-memory: " "%s\n", strerror ( rc ) ); return rc; } /* Update based on memory regions in the reserved-memory node */ if ( ( rc = fdtmem_update_node ( region, fdt, offset, NULL, MEMMAP_FL_RESERVED ) ) != 0 ) return rc; return 0; } /** * Describe memory region * * @v min Minimum address * @v max Maximum accessible physical address * @v fdt Device tree * @v region Region descriptor to fill in */ static void fdtmem_describe ( uint64_t min, uint64_t max, struct fdt *fdt, struct memmap_region *region ) { uint64_t inaccessible; /* Initialise region */ memmap_init ( min, region ); /* Update region based on device tree */ fdtmem_update_tree ( region, fdt ); /* Treat inaccessible physical memory as such */ inaccessible = ( max + 1 ); memmap_update ( region, inaccessible, -inaccessible, MEMMAP_FL_INACCESSIBLE, NULL ); } /** * Get length for copy of iPXE and device tree * * @v fdt Device tree * @ret len Total length */ static size_t fdtmem_len ( struct fdt *fdt ) { size_t len; /* Calculate total length and check device tree alignment */ len = ( memsz + fdt->len ); assert ( ( memsz % FDT_MAX_ALIGN ) == 0 ); /* Align length. Not technically necessary, but keeps the * resulting memory maps looking relatively sane. */ len = ( ( len + PAGE_SIZE - 1 ) & ~( PAGE_SIZE - 1 ) ); return len; } /** * Find a relocation address for iPXE * * @v hdr FDT header * @v max Maximum accessible physical address * @ret new New physical address for relocation * * Find a suitably aligned address towards the top of existent 32-bit * memory to which iPXE may be relocated, along with a copy of the * system device tree. * * This function may be called very early in initialisation, before * .data is writable or .bss has been zeroed. Neither this function * nor any function that it calls may write to or rely upon the zero * initialisation of any static variables. */ physaddr_t fdtmem_relocate ( struct fdt_header *hdr, physaddr_t max ) { struct fdt fdt; struct memmap_region region; physaddr_t addr; physaddr_t next; physaddr_t old; physaddr_t new; physaddr_t try; size_t len; int rc; /* Sanity check */ assert ( ( max_align & ( max_align - 1 ) ) == 0 ); /* Get current physical address */ old = virt_to_phys ( _prefix ); /* Parse FDT */ if ( ( rc = fdt_parse ( &fdt, hdr, -1UL ) ) != 0 ) { DBGC ( hdr, "FDTMEM could not parse FDT: %s\n", strerror ( rc ) ); /* Refuse relocation if we have no FDT */ return old; } /* Determine required length */ len = fdtmem_len ( &fdt ); assert ( len > 0 ); DBGC ( hdr, "FDTMEM requires %#zx + %#zx => %#zx bytes for " "relocation\n", memsz, fdt.len, len ); /* Limit relocation to 32-bit address space * * Devices with only 32-bit DMA addressing are relatively * common even on systems with 64-bit CPUs. Limit relocation * of iPXE to 32-bit address space so that I/O buffers and * other DMA allocations will be accessible by 32-bit devices. */ if ( max > FDTMEM_MAX32 ) max = FDTMEM_MAX32; /* Construct memory map and choose a relocation address */ new = old; for ( addr = 0, next = 1 ; next ; addr = next ) { /* Describe region and in-use memory */ fdtmem_describe ( addr, max, &fdt, ®ion ); memmap_update ( ®ion, old, memsz, MEMMAP_FL_USED, "iPXE" ); memmap_update ( ®ion, virt_to_phys ( hdr ), fdt.len, MEMMAP_FL_RESERVED, "FDT" ); next = ( region.max + 1 ); /* Dump region descriptor (for debugging) */ DBGC_MEMMAP ( hdr, ®ion ); assert ( region.max >= region.min ); /* Use highest possible region */ if ( memmap_is_usable ( ®ion ) && ( ( next == 0 ) || ( next >= len ) ) ) { /* Determine candidate address after alignment */ try = ( ( next - len ) & ~( max_align - 1 ) ); /* Use this address if within region */ if ( try >= addr ) new = try; } } DBGC ( hdr, "FDTMEM relocating %#08lx => [%#08lx,%#08lx]\n", old, new, ( ( physaddr_t ) ( new + len - 1 ) ) ); return new; } /** * Copy and register system device tree * * @v hdr FDT header * @v max Maximum accessible physical address * @ret rc Return status code */ int fdtmem_register ( struct fdt_header *hdr, physaddr_t max ) { struct fdt_header *copy; struct fdt fdt; int rc; /* Record maximum accessible physical address */ fdtmem_max = max; /* Parse FDT to obtain length */ if ( ( rc = fdt_parse ( &fdt, hdr, -1UL ) ) != 0 ) { DBGC ( hdr, "FDTMEM could not parse FDT: %s\n", strerror ( rc ) ); return rc; } /* Copy device tree to end of iPXE image */ copy = ( ( void * ) _end ); memcpy ( copy, hdr, fdt.len ); /* Update in-use memory region */ memmap_use ( &fdtmem_used, virt_to_phys ( _prefix ), fdtmem_len ( &fdt ) ); /* Register copy as system device tree */ if ( ( rc = fdt_parse ( &sysfdt, copy, -1UL ) ) != 0 ) { DBGC ( hdr, "FDTMEM could not register FDT: %s\n", strerror ( rc ) ); return rc; } assert ( sysfdt.len == fdt.len ); /* Dump system memory map (for debugging) */ memmap_dump_all ( 1 ); return 0; } /** * Describe memory region from system memory map * * @v min Minimum address * @v hide Hide in-use regions from the memory map * @v region Region descriptor to fill in */ static void fdtmem_describe_region ( uint64_t min, int hide, struct memmap_region *region ) { /* Describe memory region based on device tree */ fdtmem_describe ( min, fdtmem_max, &sysfdt, region ); /* Update memory region based on in-use regions, if applicable */ if ( hide ) memmap_update_used ( region ); } PROVIDE_MEMMAP ( fdt, memmap_describe, fdtmem_describe_region ); PROVIDE_MEMMAP_INLINE ( fdt, memmap_sync );