SceExcpmgr

SceExcpmgr is a kernel module that sets up exception handling. A version exists in both worlds. In non-secure world, after the kernel is booted up, the exception handlers pointed to by VBAR all jump into code in this module.

Module

This module exists in both non-secure and secure world. The non-secure world SELF can be found in os0:kd/excpmgr.skprx.

Version	World	Privilege
1.69-3.65	Non-secure	Kernel
1.69	Secure	Kernel

Libraries

This module only exports kernel libraries.

Known NIDs

Version	Name	World	Visibility	NID
1.69-3.60	SceExcpmgrForKernel	Non-secure	Kernel	0x4CA0FDD5
3.65	SceExcpmgrForKernel	Non-secure	Kernel	0x1496A5B5
1.69-1.80	SceExcpmgrForTZS	Secure	Kernel	0x8F526F35

Types

//All data in this structure are per-core (field_name[0] belongs to CPU0, field_name[1] to CPU1, etc)
typedef struct _SceExcpmgrData {
    //Incremented by the first exception handler, must be 1 when then decremented before returning from an exception.
    //If not, raise a nested exception kpanic.
    int nestedExceptionCount[4];
    int unused[4]; //Seemingly unused
    void *ExcpStackTop[4]; //Stack size is 0x1000
    void *ExcpStackBottom[4];
} SceExcpmgrData;

//Exception handlers' prototype
typedef void(SceExcpmgrExceptionHandler)(SceExcpmgrExceptionContext* context, SceExcpmgrExceptionHandlingCode code);

//Parameter for the RegisterHandler/ReleaseHandler functions
typedef struct __attribute__((aligned(4))) _SceExcpmgrExceptionHandlerContext {
    struct _SceExcpmgrExceptionHandlerContext *next; //Points to the next handler in the chain
    uint32_t must_be_zero; //Unused - probably required for alignement reasons
    //ARM code of the exception handler goes here - exception handlers cannot be written in Thumb.
    //This must be the start of a SceExcpmgrExceptionHandler function.
} SceExcpmgrExceptionHandlerContext;


//Structure that holds the CPU's state at the moment when an exception was raised
typedef struct _SceExcpmgrExceptionContext { //Size is 0x400 on FW 3.60
    uint32_t r0;
    uint32_t r1;
    uint32_t r2;
    uint32_t r3;
    uint32_t r4;
    uint32_t r5;
    uint32_t r6;
    uint32_t r7;
    uint32_t r8;
    uint32_t r9;
    uint32_t r10;
    uint32_t r11;
    uint32_t r12;
    uint32_t sp;
    uint32_t lr;
    uint32_t address_of_faulting_instruction;
    uint32_t exception_code; //Set to 1 in UNDEFINED handler, 3 in PABT handler, 4 in DABT handler
    uint32_t SPSR;
    uint32_t CPACR;
    uint32_t FPSCR;
    uint32_t FPEXC;
    uint32_t CONTEXTIDR;
    uint32_t TPIDRURW;
    uint32_t TPIDRURO;
    uint32_t TPIDRPRW;
    uint32_t TTBR1;
    uint32_t unused68; //Seemingly not populated
    uint32_t DACR;
    uint32_t DFSR;
    uint32_t IFSR;
    uint32_t DFAR;
    uint32_t IFAR;
    uint32_t PAR;
    uint32_t TEEHBR;
    uint32_t PMCR;
    uint32_t PMCNTENSET;
    uint32_t PMCNTENSET_2; //Second copy of PMCNTENSET
    uint32_t PMSELR;
    uint32_t PMCCNTR;
    uint32_t PMUSERENR;
    uint32_t PMXEVTYPER0;
    uint32_t PMXEVCNTR0;
    uint32_t PMXEVTYPER1;
    uint32_t PMXEVCNTR1;
    uint32_t PMXEVTYPER2;
    uint32_t PMXEVCNTR2;
    uint32_t PMXEVTYPER3;
    uint32_t PMXEVCNTR3;
    uint32_t PMXEVTYPER4;
    uint32_t PMXEVCNTR4;
    uint32_t PMXEVTYPER5;
    uint32_t PMXEVCNTR5;
    uint32_t unusedD0;
    uint32_t unkD4;         //Comes from SceVfpIntRegs[localCore].field_0x100
    uint32_t DBGSCRext;
    uint32_t unusedDC[9];  //Seemingly not populated
    uint64_t VFP_registers[32]; //Content of registers d0-d31
    uint32_t unk200[128];       //Comes from SceVfpIntRegs[localCore].field_0x200
} SceExcpmgrExceptionContext;

typedef enum {
    //For all codes != 3, calling the last handler in the chain should call sceKernelSysrootReturnFromExcpToThreadForKernel and return properly
    SCE_EXCPMGR_EXCEPTION_HANDLING_CODE_0 = (int16_t)0,
    SCE_EXCPMGR_EXCEPTION_HANDLING_CODE_1 = (int16_t)1,
    SCE_EXCPMGR_EXCEPTION_HANDLING_CODE_2 = (int16_t)2,
    //If this code reaches the last handler in the chain, calls SceDebugForKernel_082B8D6A then loops infinitely
    SCE_EXCPMGR_EXCEPTION_NOT_HANDLED_FATAL = (int16_t)3,
    SCE_EXCPMGR_EXCEPTION_HANDLING_CODE_4 = (int16_t)4
} SceExcpmgrExceptionHandlingCode;

To find

Functions with the following names may exist in SceExcpmgr :

   sceKernelDefaultHandlerCfunc
   sceKernelDefaultHandlerSvcCfunc
   sceKernelDefaultHandlerIrqCfunc
   sceKernelDefaultHandlerReservedCfunc
   sceKernelPanicHandlerUndefCfunc
   sceKernelPanicHandlerDabtCfunc
   sceKernelPanicHandlerPabtCfunc

SceExcpmgrForKernel

sceKernelRegisterExceptionHandlerForKernel

Version	NID
0.990-3.60	0x03499636
3.65	0x00063675

Temp name was sceExcpmgrRegisterHandlerForKernel.

Installs an exception handler.

int sceKernelRegisterExceptionHandlerForKernel(int excpcode, int priority, SceExcpmgrExceptionHandlerContext *handler);

The exception handler must be ARM code, and not Thumb code. Allowed priority values are from 0 (most important) to 7 (least important), including them. Specifying priority 0 will install the handler directly in VBAR, which means its code will run directly when an exception raises (and as such needs to build the exception context itself).

excpcode can be:

• Reset (RESET): 0
• Undefined Instruction (UNDEF): 1
• Supervisor Call (SVC): 2
• Prefetch Abort (PABT): 3
• Data Abort (DABT): 4
• Reserved (RESERVED): 5
• Interrupt (IRQ): 6
• Fast Interrupt (FIQ): 7

The syscall handler in FW 1.50 is SceExcpmgr_func_0x81000E40.

sceKernelRegisterDefaultExceptionHandlerForKernel

Version	NID
0.990-3.60	0xFFCCB5F9
3.65	0x416C0E20

Installs an exception handler for all exceptions. If no exception handler is already installed for an exception, the handler will be installed in the VBAR. handler must be the same parameter that would be passed to sceKernelRegisterExceptionHandlerForKernel.

SceInt32 sceKernelRegisterDefaultExceptionHandlerForKernel(SceExcpmgrExceptionHandlerContext *handler);

sceKernelReleaseExceptionHandlerForKernel

Version	NID
0.990-3.60	0xE04AE286

Uninstalls an exception handler.

Pass the same arguments as provided to sceKernelRegisterExceptionHandlerForKernel.

int sceKernelReleaseExceptionHandlerForKernel (int excpcode, SceExcpmgrExceptionHandlerContext *handler);

sceKernelReleaseDefaultExceptionHandlerForKernel

Version	NID
0.990	0x917A6D2B
3.60	not present

sceKernelInitialHandlerDebugUndefCfuncForKernel

Version	NID
0.990-3.60	0xB77DCBD6

Logs some information about the CPU state and backtrace then returns. Freezes on infinite loop if currentHandlerIndex is superior to 1.

void sceKernelInitialHandlerDebugUndefCfuncForKernel (SceExcpmgrExceptionContext* context);

sceKernelInitialHandlerDebugPabtCfuncForKernel

Version	NID
0.990-3.60	0x25C0C91B

Logs some information about the CPU state and backtrace then returns. Freezes on infinite loop if currentHandlerIndex is superior to 1.

void sceKernelInitialHandlerDebugPabtCfuncForKernel(SceExcpmgrExceptionContext* context);

sceKernelInitialHandlerDebugDabtCfuncForKernel

Version	NID
0.990-3.60	0xFFFA3353

Logs some information about the CPU state and backtrace then returns. Freezes on infinite loop if currentHandlerIndex is superior to 1.

void sceKernelInitialHandlerDebugDabtCfuncForKernel(SceExcpmgrExceptionContext* context);

sceKernelPanicHandlerReturnFromNestedExceptionCfuncForKernel

Version	NID
0.990-3.60	0xD17EEE40

void sceKernelPanicHandlerReturnFromNestedExceptionCfuncForKernel(SceExcpmgrExceptionContext* context);

sceKernelDefaultHandlerResetCfuncForKernel

Version	NID
0.990-3.60	0xA90AC525
3.65	0x4337DD78

Returns a pointer to the handler previously registered by sceKernelRegisterDefaultExceptionHandlerForKernel.

SceExcpmgrExceptionHandlerContext *sceKernelDefaultHandlerResetCfuncForKernel(void);

sceKernelGetExcpStackBottomForKernel

Version	NID
0.990-3.60	0x4C603645
3.65	0x5420ED8F

Returns the exception stack bottom for specified CPU core. The stack bottom is the highest address of the stack.

void* sceKernelGetExcpStackBottomForKernel(int coreNum) {
    return sceExcpmgrGetDataForKernel()->ExcpStackBottom[coreNum];
}

sceExcpmgrGetDataForKernel

Version	NID
3.60	0x08CB30E6

Get exception data pointer (for use by handlers).

SceExcpmgrData* sceExcpmgrGetDataForKernel(void);

SceExcpmgrForKernel_3AE9AEE1

Version	NID
3.60	0x3AE9AEE1

Sets a callback function ran by the default UNDEF exception handler before calling the next handler in the chain.

//NOTE : context passed to callback lacks VFP registers
void SceExcpmgrForKernel_3AE9AEE1(void (*callback)(SceExcpmgrExceptionContext*));

SceExcpmgrForKernel_4FF90618

Version	NID
0.990 - 3.60	0x4FF90618

Sets whether or not watchpoint control debug registers (DBGWCR0-DBGWCR4) should be left untouched by the UNDEF/DABT/PABT handlers. Registers are otherwise zero'ed out.

void SceExcpmgrForKernel_4FF90618(SceBool keepRegisters);

SceExcpmgrForKernel_7ADF11DB

Version	NID
3.60	0x7ADF11DB

Sets a callback function ran by the default DABT exception handler before calling the next handler in the chain.

//NOTE : context passed to callback lacks VFP registers
void SceExcpmgrForKernel_7ADF11DB(void (*callback)(SceExcpmgrExceptionContext*));

SceExcpmgrForKernel_8D223205

Version	NID
3.60	0x8D223205
3.65	0x58F7212B

Sets a callback function ran by the default PABT exception handler before calling the next handler in the chain.

//NOTE : context passed to callback lacks VFP registers
void SceExcpmgrForKernel_8D223205(void (*callback)(SceExcpmgrExceptionContext*));

SceExcpmgrForKernel_A66DDFA3

Version	NID
0.990 - 3.60	0xA66DDFA3

Sets whether or not breakpoint control debug registers (DBGBCR0-DBGBCR5) should be left untouched by the UNDEF/DABT/PABT handlers. Registers are otherwise zero'ed out.

void SceExcpmgrForKernel_A66DDFA3(SceBool keepRegisters);

SceExcpmgrForKernel_C45C0D3D

Version	NID
3.60	0xC45C0D3D

Set the "memory access error range". If a DABT exception occurs and PC is located in the range (inclusive) provided by this function, a subroutine of the default DABT handler will return SCE_KERNEL_ERROR_INVALID_MEMORY_ACCESS which in turn makes the handler return to the instruction right after the faulting one.

void SceExcpmgrForKernel_C45C0D3D(uintptr_t rangeStart, uintptr_t rangeStop);

SceExcpmgrForKernel_D464A9A7

Version	NID
3.60	0xD464A9A7

Returns the current nested exception count, or 0 if current TPIDRPRW is non-NULL.

int SceExcpmgrForKernel_D464A9A7(void);

SceExcpmgrForTZS

SceExcpmgrForTZS_get_default_excp_handler

Version	NID
0.931-1.80	0x07A5790B

sceKernelReleaseExceptionHandlerForTZS

Version	NID
0.931-1.80	0x166C9362

sceKernelReleaseDefaultExceptionHandlerForTZS

Version	NID
0.931-1.80	0x6282E52C

sceKernelRegisterDefaultExceptionHandlerForTZS

Version	NID
0.931-1.80	0xA0434735

sceKernelRegisterMonitorEntryForTZS

Version	NID
0.931-3.60	0xAC297406

// some_id must be in the 0-7 range
int sceKernelRegisterMonitorEntryForTZS(int some_id, void *pParam);

sceKernelRegisterExceptionHandlerForTZS

Version	NID
0.931-1.80	0xDD4C680D

Exceptions

SVC

SVC (Supervisor Call), more commonly called Syscalls (system calls), is what allows to interact with non-secure kernel from usermode.

The SVC interface is defined in non-secure kernel as:

Register	Value
R0	First argument
R1	Second argument
R2	Third argument
R3	Fourth argument
R12	Syscall number

On return, R1-R3 and R12 are cleared to 0x0 or 0xDEADBEEF to prevent any data leaks. All user pointers passed to syscalls are accessed with ARM instructions LDRT and STRT for hardware forced permission checks. Syscalls 0x0 - 0xFF are likely a "fastcall" interface that do not mask interrupts or set the DACR, however currently are no such fastcalls defined. Syscalls 0x100 - 0xFFF are made with IRQ interrupts masked and DACR set to 0xFFFF0000 (to prevent access to certain memory domains). Any other syscall numbers are invalid.

System calls are handled in "system" mode defined in ARMv7 (mode 0b11111).

User exported functions loaded by SceKernelModulemgr are exported as syscalls. The number assigned to the syscall are randomized with respect to each library but not within a library. That means, for example, two functions exported by a library will always be some syscall number apart even though that number will change on each boot.

There is no SVC in secure world because all code in secure world is running as kernel.

SMC

SMC (Secure Monitor Call) is what allows to interact with ARM TrustZone from non-secure kernel.

The SMC interface for making a non-secure kernel call to secure kernel is:

Register	Value
R0	First argument
R1	Second argument
R2	Third argument
R3	Fourth argument
R12	SMC number

The SMC interface is very similar to SVC interface. The SMC handler and MVBAR is set up in Secure World by SceExcpmgrForTZS.

0x0 - 0xFF are fast service calls. 0x100 - 0xFFF are normal service calls ran with IRQs masked.

Secure services are ran in ARM system processor mode (0b11111) in the Secure World.

SMC calls are registered by SceIntrmgrForTZS functions.

SMC calls

Number	Module	Arguments	Notes
0x101		int AllocSharedMemory_S(void *pPA, SceSize size);
0x103		int FreeSharedMemory_S(void);	Frees the allocation of virtual ranges: 0x40000000-0x40100000, 0x50000000-0x51000000 and 0x51000000-0x52000000 with UID 0x10007. This is SKBL only and does not affect NSKBL.
0x104		int PervasiveAccessMode(int mode, SceBool cmd);	cmd: 0 clear, 1 set
0x105		int TASAccessMode(int mode, SceBool cmd);	cmd: 0 clear, 1 set
0x106		int Pervasive2AccessMode(int mode, SceBool cmd);	cmd: 0 clear, 1 set
0x107		int RegbusAccessMode(int mode, SceBool cmd);	cmd: 0 clear, 1 set
0x10A		int GetGrabCmpMap(int index);	Gets GRAB Compatibility Map.
0x10B		int SetGrabCmpMap(int index, int map);	Sets GRAB Compatibility Map.
0x10C	SceKernelBusError	int BusErrorDump(void);	Used by SceKernelBusError when a bus error is handled, just before getting bus error info. Writes bus registers to (shared memory + 0x4000).
0x10D	SceKernelBusError	int BusErrorDump2(void);	Used by SceKernelBusError when a bus error is handled, just before getting bus error info. Writes bus registers to (shared memory + 0x6000). Replacement of SMC 0x10C that writes to offset 0x6000 instead of 0x4000 and calls sceKernelDcacheCleanInvalidateRange before returning.
0x10E	SceKernelBusError	int BusErrorClear(void);	On FW 0.931, prints a tree of all bus states. On FW 3.60, does nothing and return 0.
0x10F		int smc_ple_flush_kill_and_l1_dcache_clean_invalidate_all(void);	Flushes (and kills if there is activity) the PLE (Preload Engine) and then cleans and invalidates all the L1 Dcache.
0x110	SceDriverTzs	int smc_bus_set_state(int bus, int command);	bus: 1 -> used by SceEnumWakeUp, 2 -> used to enable/disable some things used by the PSP Emulator; maybe CPU, or memory for example. Command: 0 (stop), 1 (start), 2 (LCD DMAC init).
0x111	SceDriverTzs		Related to bus.
0x113	SceDriverTzs		Related to bus.
0x114	SceDriverTzs	int smc_bus_freq_op(SceUInt32 op, SceUInt32 freq_level);	op: 0 - Set bus frequency, 1 - Get bus frequency, 2 - Set GPU Xbar frequency, 3 - Get GPU Xbar frequency
0x117	SceDriverTzs	int smc_cdram_enable(void);	Seems to enable the CDRAM (by using the SceEmcTop registers).
0x118	SceDriverTzs	int smc_0x118(void);	Seems to enable something CDRAM related.
0x119	SceDriverTzs	int smc_0x119(void);	Seems to disable something CDRAM related.
0x11A	SceDriverTzs	int sceSysconSetPowerMode(int type, int mode);	Set power mode. See sceSysconSetPowerModeForDriver.
0x11B	SceDriverTzs	int smc_0x11B(int mode, SceBool cmd);	mode: must be < 0x1000, cmd: 0 set, 1 clear
0x11C	SceDriverTzs	int smc_0x11C(SceUInt32 handle, SceInt32 value);	Used by SceLowio#SceGrabForDriver_188BBCC8.
0x11D	SceDriverTzs	int smc_compat_set_memory_bank_start_paddr(int bank, void *pPA);	Valid banks: 0-7, and physical addresses: 0x20000000-0x2FFFFFFF and 0x42800000-0x7FFFFFFF.
0x11E	SceDriverTzs	int smc_compat_set_state_ex(int command, int ex);	Replacement for SMC 0x110. Used to enable/disable some things used by the PSP Emulator. Maybe the CPU, or memory for example. Command: 0 (stop), 1 (start), 2 (LCD DMAC init). Ex is only used for start (maybe for resume/suspend).
0x11F	SceDriverTzs	int smc_0x11F(int unk);	Valid unk: 1-3. Waits something like a semaphore.
0x120	SceDriverTzs	int smc_compat_get_memory_bank_start_paddr(int bank);	Valid banks 0-7.
0x121	SceDriverTzs	int smc_0x121(int bank1, int bank2);	Valid banks 0-7.
0x122	SceDriverTzs	int smc_intr_crash(int type, void *pTTBR0, void *pVBAR, void *pSysbase);	type: 0 (exception), 1 (panic_or_assertion_failed)
0x12D		int sceSblSmSchedInvoke(SceBool priority, void *sm_self_paddr, SceUInt32 num_pa_range, SceSblTzsBridgeArgArea area);	Used by sceSblSmSchedProxyInvokeForKernel.
0x12E		int sceSblSmSchedWait(SceSmSchedRequestId req_id, SceSblTzsBridgeArgArea area);	Used by sceSblSmSchedProxyWaitForKernel.
0x12F		int sceSblSmSchedGetStatus(SceSmSchedRequestId req_id, SceSblTzsBridgeArgArea area);	Used by sceSblSmSchedProxyGetStatusForKernel.
0x130		int sceSblSmSchedKill(SceSmSchedRequestId req_id);	Used by sceSblSmSchedProxyKillForKernel.
0x131		Reserved (on FWs 0.931-3.60).
0x132		Reserved (on FWs 0.931-3.60).
0x133		int smc_sm_sched_proxy_call_func(SceSmSchedRequestId req_id, int mailbox_id, SceUInt32 mailval);	Used by sceSblSmSchedProxyCallFuncForKernel. mailval is paddr(SceSblSmschedCallFuncCommand) | 1.
0x134		int sceSblSmSchedReadArm2Cry(SceSmSchedRequestId req_id, int mailbox_id, SceUInt32 *pMailval);	Used by sceSblSmSchedProxyReadArm2CryForKernel.
0x135		int sceSblSmSchedWriteArm2Cry(SceSmSchedRequestId req_id, int mailbox_id, SceUInt32 mailval);	Used by sceSblSmSchedProxyWriteArm2CryForKernel.
0x136		int sceSblSmSchedWriteCry2Arm(SceSmSchedRequestId req_id, int mailbox_id, SceUInt32 mailval);	Used by sceSblSmSchedProxyWriteCry2ArmForKernel.
0x137		int sceSblSmSchedReadCry2Arm(SceSmSchedRequestId req_id, int mailbox_id, SceUInt32 *pMailval);	Used by sceSblSmSchedProxyReadCry2ArmForKernel.
0x138		int sceSblSmSchedRegisterIntrHandler(SceSmSchedRequestId req_id, int mailbox_id);	Used by sceSblSmSchedProxyRegisterIntrHandlerForKernel.
0x139		int sceSblSmSchedReleaseIntrHandler(SceSmSchedRequestId req_id, int mailbox_id);	Used by sceSblSmSchedProxyReleaseIntrHandlerForKernel.
0x13A		int smc_sm_sched_proxy_enable_all_cry2arm_interrupts(SceSmSchedRequestId req_id, int mailbox_id, SceSblTzsBridgeArgArea area);	Interrupt Cry2Arm set enable.
0x13B		int smc_sm_sched_proxy_uninitialize(void);	Interrupt Cry2Arm clear enable. Used by sceSblSmSchedProxyUninitializeForKernel.
0x13C		int smc_sm_sched_proxy_execute_sk_command(sk_cmd_index cmd_index);	Executes a Secure Kernel command. Used by sceSblSmSchedProxyExecuteSKCommandForKernel.
0x168		int smc_0x168_dmac(int index, int value);	SceDmacmgrDmac related. Writes value to SceDmacmgrDmacN + 0x100. Maybe key_id related.
0x169		int smc_0x169_dmac(int index, int value);	SceDmacmgrDmac related. Writes value to SceDmacmgrDmacN + 0x104. Maybe key_id related.
0x16A		int smc_l2_write_control_register(int value);	Flushes and invalidates the entire L2 Cache (Clean and Invalidate by Way with way = 0xFFFF, offset 0x7FC), then performs an L2 Cache Sync (offset 0x730), and finally writes value to the L2 Control Register (offset 0x100).
0x16B		int smc_l2_write_auxiliary_control_register(int value);	Writes value to the L2 Auxiliary Control Register (offset 0x104).

Aborts

On development units, data and prefetch aborts can handle BKPT instruction for software breakpoints. SceDebug uses this to handle usermode breakpoints. There is no built-in support for BKPT in kernel code.

SceSysmem uses data aborts with the LDRT and STRT instructions to implement user pointer checking. When LDRT/STRT throws a MMU data exception because of an invalid access and the exception came from SceSysmem#sceKernelCopyFromUserForDriver or SceSysmem#sceKernelCopyToUserForDriver or related functions, the data abort handler will resume execution.

IRQ

IRQs are only handled in non-secure world. An IRQ in secure world is fatal. See SceKernelIntrMgr.

FIQ

FIQs are only handled in secure world because of the bit set in the SCR. Because of this, it is likely that secure devices such as the F00D Processor use FIQs to communicate with the Cortex A9 cores. See SceKernelIntrMgr.