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target/riscv: decrease modify_privilege function nesting level #1170

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Nov 26, 2024
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target/riscv: decrease modify_privilege function nesting level #1170

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58 changes: 35 additions & 23 deletions src/target/riscv/riscv-013.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3092,36 +3092,48 @@ static int read_sbcs_nonbusy(struct target *target, uint32_t *sbcs)
}
}

/* TODO: return mem_access_result_t */
static int modify_privilege(struct target *target, uint64_t *mstatus, uint64_t *mstatus_old)
{
if (riscv_virt2phys_mode_is_hw(target)
&& has_sufficient_progbuf(target, 5)) {
/* Read DCSR */
uint64_t dcsr;
if (register_read_direct(target, &dcsr, GDB_REGNO_DCSR) != ERROR_OK)
return ERROR_FAIL;
assert(mstatus);
assert(mstatus_old);
if (!riscv_virt2phys_mode_is_hw(target))
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return ERROR_OK;

/* Read and save MSTATUS */
if (register_read_direct(target, mstatus, GDB_REGNO_MSTATUS) != ERROR_OK)
return ERROR_FAIL;
*mstatus_old = *mstatus;
/* TODO: handle error in this case
* modify_privilege function used only for program buffer memory access.
* Privilege modification requires progbuf size to be at least 5 */
if (!has_sufficient_progbuf(target, 5)) {
LOG_TARGET_WARNING(target, "Can't modify privilege to provide "
"hardware translation: program buffer too small.");
return ERROR_OK;
}

/* Read DCSR */
riscv_reg_t dcsr;
if (register_read_direct(target, &dcsr, GDB_REGNO_DCSR) != ERROR_OK)
return ERROR_FAIL;

/* If we come from m-mode with mprv set, we want to keep mpp */
if (get_field(dcsr, CSR_DCSR_PRV) < 3) {
/* MPP = PRIV */
*mstatus = set_field(*mstatus, MSTATUS_MPP, get_field(dcsr, CSR_DCSR_PRV));
/* Read and save MSTATUS */
if (register_read_direct(target, mstatus, GDB_REGNO_MSTATUS) != ERROR_OK)
return ERROR_FAIL;
*mstatus_old = *mstatus;

/* MPRV = 1 */
*mstatus = set_field(*mstatus, MSTATUS_MPRV, 1);
/* If we come from m-mode with mprv set, we want to keep mpp */
if (get_field(dcsr, CSR_DCSR_PRV) == PRV_M)
return ERROR_OK;

/* Write MSTATUS */
if (*mstatus != *mstatus_old)
if (register_write_direct(target, GDB_REGNO_MSTATUS, *mstatus) != ERROR_OK)
return ERROR_FAIL;
}
}
/* mstatus.mpp <- dcsr.prv */
*mstatus = set_field(*mstatus, MSTATUS_MPP, get_field(dcsr, CSR_DCSR_PRV));

return ERROR_OK;
/* mstatus.mprv <- 1 */
*mstatus = set_field(*mstatus, MSTATUS_MPRV, 1);

/* Write MSTATUS */
if (*mstatus == *mstatus_old)
return ERROR_OK;

return register_write_direct(target, GDB_REGNO_MSTATUS, *mstatus);
}

static int read_memory_bus_v0(struct target *target, target_addr_t address,
Expand Down