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.

Known NIDs

Version	Name	World	Privilege	NID
1.69	SceExcpmgr	Non-secure	Kernel	0xBBCA9AB6
3.60	SceExcpmgr	Non-secure	Kernel	0xF3D9E37C
3.65	SceExcpmgr	Non-secure	Kernel	0xB5616C8A
1.69	SceExcpmgr	Secure	Kernel	0x93332B9A

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

To find

   sceKernelDefaultHandlerCfunc
   sceKernelDefaultHandlerSvcCfunc
   sceKernelDefaultHandlerIrqCfunc
   sceKernelDefaultHandlerReservedCfunc
   
   sceKernelPanicHandlerUndefCfunc
   sceKernelPanicHandlerDabtCfunc
   sceKernelPanicHandlerUndefCfunc
   sceKernelPanicHandlerPabtCfunc

These 8 function names must be of the following NIDs:

         sceExcpmgrGetDataForKernel: 0x08CB30E6
         SceExcpmgrForKernel_3AE9AEE1: 0x3AE9AEE1
         SceExcpmgrForKernel_4FF90618: 0x4FF90618
         SceExcpmgrForKernel_7ADF11DB: 0x7ADF11DB
         SceExcpmgrForKernel_8D223205: 0x8D223205
         SceExcpmgrForKernel_A66DDFA3: 0xA66DDFA3
         SceExcpmgrForKernel_C45C0D3D: 0xC45C0D3D
         SceExcpmgrForKernel_D464A9A7: 0xD464A9A7

SceExcpmgrForKernel

sceKernelRegisterExceptionHandlerForKernel

Version	NID
0.990-3.60	0x03499636

Wrong name was ksceExcpmgrRegisterHandler.

Installs an exception handler.

int sceKernelRegisterExceptionHandlerForKernel(int excpcode, int priority, void *function);

The function must be ARM and not thumb, and the allowed priority values are from 0 to 7 (including them).

Where excpcode can be:

• Reset: excpcode = 0
• Undefined Instruction: excpcode = 1
• Supervisor Call: excpcode = 2
• Prefetch Abort: excpcode = 3
• Data Abort: excpcode = 4
• Not used: excpcode = 5
• IRQ interrupt: excpcode = 6
• FIQ interrupt: excpcode = 7

The syscall handler at 1.50 is SceExcpmgr_func_0x81000E40

sceKernelRegisterDefaultExceptionHandlerForKernel

Version	NID
0.990-3.60	0xFFCCB5F9

sceKernelReleaseExceptionHandlerForKernel

Version	NID
0.990-3.60	0xE04AE286

sceKernelReleaseDefaultExceptionHandlerForKernel

Version	NID
0.990	0x917A6D2B

sceKernelInitialHandlerDebugUndefCfuncForKernel

Version	NID
0.990-3.60	0xB77DCBD6

sceKernelInitialHandlerDebugPabtCfuncForKernel

Version	NID
0.990-3.60	0x25C0C91B

sceKernelInitialHandlerDebugDabtCfuncForKernel

Version	NID
0.990-3.60	0xFFFA3353

sceKernelPanicHandlerReturnFromNestedExceptionCfuncForKernel

Version	NID
0.990-3.60	0xD17EEE40

void sceKernelRegisterExceptionHandlerForKernel(int a1);

sceKernelDefaultHandlerResetCfuncForKernel

Version	NID
0.990-3.60	0xA90AC525

sceKernelGetExcpStackBottomForKernel

Version	NID
0.990-3.60	0x4C603645

sceExcpmgrGetDataForKernel

Version	NID
3.60	0x08CB30E6

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	Secure service 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	Arguments	Notes
0x101	int smc_set_sce_shared_memory_block_s(unsigned int paddr, unsigned int size);
0x103	int smc_disable_virtual_ranges(void);	Disables the virtual ranges: 0x40000000-0x40100000, 0x50000000-0x51000000 and 0x51000000-0x52000000 to the context with PID 0x10007.
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	int smc_compat_set_state(int a1, int command);	With a1 set to 2, 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).
0x114	int smc_bus_freq_op(int operation, unsigned int freq);	op = 0: Set bus frequency, op = 1: Get bus frequency, op = 2: Set GPU Xbar frequency, op = 3: Get GPU Xbar frequency
0x117	int smc_cdram_enable(void);	Seems to enable the CDRAM (by using the SceEmcTop registers).
0x118	CDRAM related	Seems to enable something CDRAM related.
0x119	CDRAM related	Seems to disable something CDRAM related.
0x11A	int smc_reset_device(int type, int mode);	Reset device (check [1] for more info).
0x11C		Used by SceLowio#SceGrabForDriver_188BBCC8.
0x11D	int smc_compat_set_memory_bank_start_paddr(int bank, unsigned int paddr);	Valid banks 0-7, and paddrs: 0x20000000-0x2FFFFFFF and 0x42800000-0x7FFFFFFF.
0x11E	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).
0x120	int smc_compat_get_memory_bank_start_paddr(int bank);	Valid banks 0-7.
0x122	int smc_intr_crash(int type, void *pTTBR0, void *pVBAR, void *pSysbase);	type: 0 (exception), 1 (panic_or_assertion_failed)
0x12D	int smc_sm_sched_proxy_invoke(SceBool priority, void *sm_self_paddr, SceUInt32 num_pairs, SceUInt32 block_index);	Used by sceSblSmSchedProxyInvokeForKernel.
0x12E	int smc_sm_sched_proxy_wait(SmOperationHandle handle, SceUInt32 block_index);	Used by sceSblSmSchedProxyWaitForKernel.
0x12F	int smc_sm_sched_proxy_get_status(SmOperationHandle handle, SceUInt32 block_index);	Used by sceSblSmSchedProxyGetStatusForKernel.
0x130	int smc_sm_sched_proxy_kill(SmOperationHandle handle);	Used by sceSblSmSchedProxyKillForKernel.
0x131	Not implemented
0x132	Not implemented
0x133	int smc_set_command_F00D_register(SmOperationHandle handle, int f00d_fifo_register_index, int f00d_fifo_register_value);	Used by sceSblSmSchedCallFuncForKernel. cmd_paddr is paddr(SceSblSmschedCallFuncCommand) | 1.
0x134	int smc_get_command_F00D_register(SmOperationHandle handle, int f00d_fifo_register_index, SceUInt32 block_index);	Used by sceSblSmSchedProxyGetCommandF00DRegisterForKernel.
0x135	int smc_set_unknown_F00D_register(SmOperationHandle handle, int f00d_fifo_register_index, int f00d_fifo_register_value);	Used by sceSblSmSchedProxySetUnknownF00DRegisterForKernel.
0x136	int smc_sm_sched_proxy_write_cry2arm(SmOperationHandle handle, int f00d_fifo_register_index, int f00d_fifo_register_value);	Used by sceSblSmSchedProxyWriteCry2ArmForKernel.
0x137	int smc_sm_sched_proxy_read_cry2arm(SmOperationHandle handle, int f00d_fifo_register_index, SceUInt32 block_index);	Used by sceSblSmSchedProxyReadCry2ArmForKernel.
0x138	int smc_sm_sched_proxy_register_intr_handler(SmOperationHandle handle, SmOperationId req_id);	Used by sceSblSmSchedProxyRegisterIntrHandlerForKernel.
0x139	int smc_sm_sched_proxy_release_intr_handler(SmOperationHandle handle, SmOperationId req_id);	Used by sceSblSmSchedProxyReleaseIntrHandlerForKernel.
0x13A	int smc_enable_all_cry2arm_interrupts(SmOperationHandle handle, SmOperationId req_id, SceUInt32 block_index);	Interrupt Cry2Arm set enable.
0x13B	int smc_sm_sched_proxy_uninitialize(void);	Interrupt Cry2Arm clear enable. Used by sceSblSmSchedProxyUninitializeForKernel.
0x13C	int smc_execute_f00d_command(F00D_cmd_index cmd_index);	Called by SceSblSsMgr SysEvent handler just before entering suspend mode. Waits by polling. Used by sceSblSmSchedProxyExecuteF00DCommandForKernel.
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.