src/arch/arm64/ramdetect.c

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2
   3 #include <types.h>
   4 #include <device/mmio.h>
   5 #include <ramdetect.h>
   6 #include <arch/exception.h>
   7 #include <arch/transition.h>
   8
   9 static enum {
  10         ABORT_CHECKER_NOT_TRIGGERED,
  11         ABORT_CHECKER_TRIGGERED,
  12 } abort_state = ABORT_CHECKER_NOT_TRIGGERED;
  13
  14 static int abort_checker(struct exc_state *state, uint64_t vector_id)
  15 {
  16         if (raw_read_esr() >> 26 != 0x25)
  17                 return EXC_RET_IGNORED; /* Not a data abort. */
  18
  19         abort_state = ABORT_CHECKER_TRIGGERED;
  20         state->elx.elr += sizeof(uint32_t); /* Jump over faulting instruction. */
  21         raw_write_elr(state->elx.elr);
  22
  23         return EXC_RET_HANDLED;
  24 }
  25
  26 static struct exception_handler sync_el0 = {.handler = &abort_checker};
  27
  28 int probe_mb(const uintptr_t dram_start, const uintptr_t size)
  29 {
  30         uintptr_t addr = dram_start + (size * MiB) - sizeof(uint32_t);
  31         void *ptr = (void *)addr;
  32
  33         abort_state = ABORT_CHECKER_NOT_TRIGGERED;
  34         exception_handler_register(EXC_VID_CUR_SP_EL0_SYNC, &sync_el0);
  35         read32(ptr);
  36         exception_handler_unregister(EXC_VID_CUR_SP_EL0_SYNC, &sync_el0);
  37         return abort_state == ABORT_CHECKER_NOT_TRIGGERED;
  38 }