ReadAs: Difference between revisions
Jump to navigation
Jump to search
(Created page with "readAs is a special functionality provided by an ''unknown'' device. It can be used to read/write data anywhere on the mapped memory, it is suspected to be a DMAC4 interface....") |
CelesteBlue (talk | contribs) No edit summary |
||
| Line 1: | Line 1: | ||
readAs is a special functionality provided by an ''unknown'' device. | readAs is a special functionality provided by an ''unknown'' cmep device. | ||
It can be used to read/write data anywhere on the mapped memory | It can be used to read/write data anywhere on the mapped memory. It is suspected to be a DMAC4 interface. | ||
It is never accessed by any currently reverse-engineered code and is not referenced in any accessible memory map. | It is never accessed by any currently reverse-engineered code and is not referenced in any accessible memory map. | ||
== Configuration | |||
== Configuration registers for cmep == | |||
{| class="wikitable" | {| class="wikitable" | ||
| Line 18: | Line 19: | ||
== Modes == | == Modes == | ||
0xE0020048 is a bitfield | |||
0xE0020048 is a bitfield. You can enable/disable some readAs features as well as change the used DMAC channel. | |||
{| class="wikitable" | {| class="wikitable" | ||
| Line 26: | Line 28: | ||
| 0 || Write data to address | | 0 || Write data to address | ||
|- | |- | ||
| 1 || Mode 2 - Alternative Secure ? | | 1 || Mode 2 - Alternative Secure? | ||
|- | |- | ||
| 2 || Mode 4 - Non- | | 2 || Mode 4 - Non-secure? | ||
|- | |- | ||
| 3 || Read/Write address byte 0 | | 3 || Read/Write address byte 0 | ||
| Line 40: | Line 42: | ||
| 30 || ?? hangs with bits 0 and 2 | | 30 || ?? hangs with bits 0 and 2 | ||
|} | |} | ||
Observation: while write mode always respects bits 3-6, read mode seems to have a set of address ranges that always read all 4 bytes. | Observation: while write mode always respects bits 3-6, read mode seems to have a set of address ranges that always read all 4 bytes. | ||
== Usage example == | == Usage example == | ||
<source lang="C"> | <source lang="C"> | ||
#define READAS_REG 0xE0020040 // readas32 device | #define READAS_REG 0xE0020040 // readas32 device | ||
| Line 86: | Line 90: | ||
== Ranges == | == Ranges == | ||
Results after a full memcmp | |||
Results after a full memcmp: | |||
<pre> | <pre> | ||
- mode 0 vs normal | - mode 0 vs normal cmep read | ||
--not available in mode 0: | --not available in mode 0: | ||
0x00300000-0x00400000 | 0x00300000-0x00400000 | ||
| Line 130: | Line 135: | ||
== Notes == | == Notes == | ||
* All read modes can be disabled by writing 0x420 to physical address 0xE0010010. | |||
* This cmep device has been updated in PS Vita SoC rev 4 compared to rev 3.2. When cmep is reset the configuration is zeroed (both in type 1 and type 8 cmep reset). | |||
Revision as of 21:59, 23 January 2022
readAs is a special functionality provided by an unknown cmep device.
It can be used to read/write data anywhere on the mapped memory. It is suspected to be a DMAC4 interface.
It is never accessed by any currently reverse-engineered code and is not referenced in any accessible memory map.
Configuration registers for cmep
| Register | Description |
|---|---|
| 0xE0020040 | Address |
| 0xE0020044 | Data (in/out) |
| 0xE0020048 | Mode |
Modes
0xE0020048 is a bitfield. You can enable/disable some readAs features as well as change the used DMAC channel.
| Bit | Description |
|---|---|
| 0 | Write data to address |
| 1 | Mode 2 - Alternative Secure? |
| 2 | Mode 4 - Non-secure? |
| 3 | Read/Write address byte 0 |
| 4 | R/W byte 1 and allow non-0x10-aligned address read |
| 5 | Read/Write address byte 2 |
| 6 | Read/Write address byte 3 |
| 30 | ?? hangs with bits 0 and 2 |
Observation: while write mode always respects bits 3-6, read mode seems to have a set of address ranges that always read all 4 bytes.
Usage example
#define READAS_REG 0xE0020040 // readas32 device
#define RAS_DEV_S 0 // default secure
#define RAS_MODE_WRITE 0b1 // write mode
#define RAS_DEV_UNK 0b10 // masks DRAM and DRAM regs, from arm bus
#define RAS_DEV_NS 0b100 // non-secure
// below options only apply to write mode and some offsets in read mode
#define RAS_B0 0b1000
#define RAS_B1 0b10000 // or RAS_NOALIGN in incompatible read offsets
#define RAS_B2 0b100000
#define RAS_B3 0b1000000
#define RAS_32 (RAS_B0 | RAS_B1 | RAS_B2 | RAS_B3)
typedef struct {
unsigned int addr;
unsigned int resp;
unsigned int mode;
} __attribute__((packed)) e002_readas32;
static volatile e002_readas32* const READAS32 = (void*)READAS_REG;
// read from [addr] with mode [mode]
static u32_t readAs(u32_t addr, u32_t mode) {
READAS32->addr = addr;
READAS32->resp = 0xDEADBABE;
READAS32->mode = mode;
while (READAS32->resp == 0xDEADBABE) {} // wait until RAS replies
return READAS32->resp;
}
// write to [addr] with mode [mode]
static void writeAs(u32_t addr, u32_t data, u32_t mode) {
READAS32->addr = addr;
READAS32->resp = data;
READAS32->mode = mode | RAS_MODE_WRITE;
}
Ranges
Results after a full memcmp:
- mode 0 vs normal cmep read --not available in mode 0: 0x00300000-0x00400000 0xE0000000-0xE0040000 0xE0058000-0xE0068000 0xE00C0000-0xE00D0000 0xE0100000-0xE0101000 0xE04D0000-0xE04DC000 0xE20A0000-0xE20B0000 0xE20C0000-0xE20D0000 0xE3110000-0xE3120000 0xE8000000-0xE8400000 - mode 2 vs 0 --not available in mode 2: 0x40000000-0xC0000000 0xE0400000-0xE0420000 0xE04E0000-0xE04E1000 0xE3000000-0xE3020000 0xE3101000-0xE3104000 0xE5000000-0xE5020000 0xE50C0000-0xE50D0000 0xE5880000-0xE6010000 0xEC340000-0xEC370000 0xED948000-0xED970000 - mode 4 vs mode 0 --not available in mode 0 (!) 0x00000000-0x00008000 0xE0100000-0xE0101000 0xE04D0000-0xE04DC000 0xE20A0000-0xE20B0000 0xE3110000-0xE3120000 --not available in mode 4: 0x00040000-0x00060000 0x00800000-0x00820000 0xE0000000-0xE0100000 0xEC000000-0xEE700000
Notes
- All read modes can be disabled by writing 0x420 to physical address 0xE0010010.
- This cmep device has been updated in PS Vita SoC rev 4 compared to rev 3.2. When cmep is reset the configuration is zeroed (both in type 1 and type 8 cmep reset).