mhpmcounter21

Machine Hardware Performance Counter 21

Programmable hardware performance counter.

The hpmcounter21 CSR is a read-only shadow of this CSR. Access to hpmcounter21 is controlled with mcounteren.HPM21 , scounteren.HPM21 , and hcounteren.HPM21 as follows:

mcounteren.HPM21	scounteren.HPM21	hcounteren.HPM21	hpmcounter21 behavior
S-mode	U-mode	VS-mode	VU-mode
0	-	-	`IllegalInstruction`	`IllegalInstruction`	`IllegalInstruction`	`IllegalInstruction`
1	0	0	read-only	`IllegalInstruction`	`VirtualInstruction`	`VirtualInstruction`
1	1	0	read-only	read-only	`VirtualInstruction`	`VirtualInstruction`
1	0	1	read-only	`IllegalInstruction`	read-only	`VirtualInstruction`
1	1	1	read-only	read-only	read-only	read-only

mcounteren.HPM21

scounteren.HPM21

hcounteren.HPM21

hpmcounter21 behavior

S-mode

U-mode

VS-mode

VU-mode

IllegalInstruction

read-only

IllegalInstruction

VirtualInstruction

read-only

VirtualInstruction

read-only

IllegalInstruction

read-only

VirtualInstruction

read-only

Attributes

CSR Address	0xb15
Defining extension	Sm
Length	64-bit
Privilege Mode	M

CSR Address

0xb15

Defining extension

Length

64-bit

Privilege Mode

Format

Figure 1. mhpmcounter21 format

Field Summary

Name Location Type Reset Value

Name	Location	Type	Reset Value
`COUNT`	63:0	RO	0

COUNT

63:0

Fields

`COUNT`

Location: mhpmcounter21[63:0]
Description

Performance counter for event selected in mhpmevent21.EVENT.

+ Increments every time event occurs unless:

+ * mcountinhibit.HPM21 or its alias scountinhibit.HPM21 is set * mhpmevent21.MINH is set and the current privilege level is M * mhpmevent21.SINH or its alias hpmevent21.SINH is set and the current privilege level is (H)S * mhpmevent21.UINH or its alias hpmevent21.UINH is set and the current privilege level is U * mhpmevent21.VSINH or its alias hpmevent21.VSINH is set and the current privilege level is VS * mhpmevent21.VUINH or its alias hpmevent21.VUINH is set and the current privilege level is VU

Unimplemented performance counter. Must be read-only 0 (access does not cause trap).

Type

RO	Read-Only Field has a hardwired value that does not change. Writes to an RO field are ignored.

Reset value: 0

Software read

This CSR may return a value that is different from what is stored in hardware.

Pruned
Original

return 0;

if (HPM_COUNTER_EN[21]) {
  return read_hpm_counter(21);
} else {
  return 0;
}