modmachine: Implement physical memory access using /dev/mem (Linux, etc).
This requires root access. And on recent Linux kernels, with CONFIG_STRICT_DEVMEM option enabled, only address ranges listed in /proc/iomem can be accessed. The above compiled-time option can be however overriden with boot-time option "iomem=relaxed". This also removed separate read/write paths - there unlikely would be a case when they're different.
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@ -29,22 +29,44 @@
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#include "py/nlr.h"
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#include "py/obj.h"
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#if MICROPY_PLAT_DEV_MEM
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#include <errno.h>
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#include <fcntl.h>
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#include <sys/mman.h>
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#endif
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#if MICROPY_PY_MACHINE
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STATIC mp_uint_t get_read_addr(mp_obj_t addr_o, uint align) {
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mp_uint_t addr = mp_obj_int_get_truncated(addr_o);
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if ((addr & (align - 1)) != 0) {
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nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "address %08x is not aligned to %d bytes", addr, align));
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}
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return addr;
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}
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#define PAGE_SIZE 4096
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#define PAGE_MASK (PAGE_SIZE - 1)
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STATIC mp_uint_t get_write_addr(mp_obj_t addr_o, uint align) {
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STATIC mp_uint_t get_addr(mp_obj_t addr_o, uint align) {
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mp_uint_t addr = mp_obj_int_get_truncated(addr_o);
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if ((addr & (align - 1)) != 0) {
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nlr_raise(mp_obj_new_exception_msg_varg(&mp_type_ValueError, "address %08x is not aligned to %d bytes", addr, align));
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}
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#if MICROPY_PLAT_DEV_MEM
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{
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// Not thread-safe
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static int fd;
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static mp_uint_t last_base = (mp_uint_t)-1;
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static mp_uint_t map_page;
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if (!fd) {
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fd = open("/dev/mem", O_RDWR | O_SYNC);
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if (fd == -1) {
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nlr_raise(mp_obj_new_exception_arg1(&mp_type_OSError, MP_OBJ_NEW_SMALL_INT(errno)));
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}
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}
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mp_uint_t cur_base = addr & ~PAGE_MASK;
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if (cur_base != last_base) {
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map_page = (mp_uint_t)mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, cur_base);
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last_base = cur_base;
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}
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addr = map_page + (addr & PAGE_MASK);
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}
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#endif
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return addr;
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}
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@ -67,7 +89,7 @@ STATIC mp_obj_t machine_mem_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t va
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return MP_OBJ_NULL; // op not supported
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} else if (value == MP_OBJ_SENTINEL) {
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// load
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mp_uint_t addr = get_read_addr(index, self->elem_size);
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mp_uint_t addr = get_addr(index, self->elem_size);
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uint32_t val;
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switch (self->elem_size) {
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case 1: val = (*(uint8_t*)addr); break;
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@ -77,7 +99,7 @@ STATIC mp_obj_t machine_mem_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t va
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return mp_obj_new_int(val);
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} else {
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// store
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mp_uint_t addr = get_write_addr(index, self->elem_size);
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mp_uint_t addr = get_addr(index, self->elem_size);
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uint32_t val = mp_obj_get_int(value);
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switch (self->elem_size) {
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case 1: (*(uint8_t*)addr) = val; break;
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@ -7,22 +7,8 @@ except ImportError:
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import sys
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sys.exit()
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import uctypes
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print(machine.mem8)
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buf = bytearray(8)
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addr = uctypes.addressof(buf)
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machine.mem8[addr] = 123
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print(machine.mem8[addr])
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machine.mem16[addr] = 12345
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print(machine.mem16[addr])
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machine.mem32[addr] = 123456789
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print(machine.mem32[addr])
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try:
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machine.mem16[1]
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except ValueError:
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@ -1,7 +1,4 @@
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<8-bit memory>
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123
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12345
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123456789
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ValueError
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ValueError
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TypeError
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@ -0,0 +1,16 @@
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# This test requires root privilege, so is usually skipped
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# It also assumes x86 legacy hardware (with Video BIOS present).
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try:
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import machine
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except ImportError:
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print("SKIP")
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import sys
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sys.exit()
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try:
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print(hex(machine.mem16[0xc0000]))
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except OSError:
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print("SKIP")
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import sys
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sys.exit()
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@ -0,0 +1 @@
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0xaa55
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@ -179,6 +179,11 @@ void mp_unix_mark_exec(void);
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#define MP_PLAT_PRINT_STRN(str, len) fwrite(str, 1, len, stdout)
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#ifdef __linux__
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// Can access physical memory using /dev/mem
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#define MICROPY_PLAT_DEV_MEM (1)
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#endif
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extern const struct _mp_obj_fun_builtin_t mp_builtin_input_obj;
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extern const struct _mp_obj_fun_builtin_t mp_builtin_open_obj;
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#define MICROPY_PORT_BUILTINS \
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