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4,008 bytes added ,  05:49, 26 February 2023
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sdknso CreateJitEnvironment implements the remaining initialization. After some validation, this uses [[SVC|svcCreateCodeMemory]] (can be called twice). Then [[#CreateJitEnvironment]] is used. TransferMemory with an user-specified buffer is created with permissions=None, which is then used with [[#LoadPlugin]]. When successful, this lastly uses [[#GetCodeAddress]].
 
sdknso CreateJitEnvironment implements the remaining initialization. After some validation, this uses [[SVC|svcCreateCodeMemory]] (can be called twice). Then [[#CreateJitEnvironment]] is used. TransferMemory with an user-specified buffer is created with permissions=None, which is then used with [[#LoadPlugin]]. When successful, this lastly uses [[#GetCodeAddress]].
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This loads the user-specified [[NRO]] into sysmodule-context ("DllPlugin"), and calls various symbols from that NRO. It seems the code writing (in cmd GenerateCode) is done via symbol-calling, allowing the NRO to handle input_buffer->code translation+writing.
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This loads the user-specified [[NRO]] into sysmodule-context ("DllPlugin"), and calls various symbols from that NRO. The code writing (in cmd GenerateCode) is done via symbol-calling, allowing the NRO to handle input_buffer->code translation+writing.
    
= jit:u =
 
= jit:u =
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The first handle is a Process handle, the rest are CodeMemory handles.
 
The first handle is a Process handle, the rest are CodeMemory handles.
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This essentially does state/object init and maps the CodeMemory regions in the user-process.
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This essentially does state/object init and maps the CodeMemory regions in the user-process. The permissions for the first CodeMemory is R-X, for the second CodeMemory it's R--. Both CodeMemory are mapped in the sysmodule with permissions RW-.
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Both CodeMemory are optional. Handling for size=0 was originally broken, this was [[Switch_System_Flaws|fixed]] with [14.0.0+].
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This copies the user-process CodeMemory addr/size for each CodeMemory to elsewhere in state, however it uses the first CodeMemory for the second CodeMemory state init as well. This is the same state used by [[#GenerateCode]] and [[#GetCodeAddress]].
    
= IJitEnvironment =
 
= IJitEnvironment =
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== GenerateCode ==
 
== GenerateCode ==
 
Takes an u32, an u64, a [[#CodeRange]], a [[#CodeRange]], a [[#Struct32]], a type-0x5 input buffer, a type-0x6 output buffer, and returns an output s32, a [[#CodeRange]], a [[#CodeRange]].
 
Takes an u32, an u64, a [[#CodeRange]], a [[#CodeRange]], a [[#Struct32]], a type-0x5 input buffer, a type-0x6 output buffer, and returns an output s32, a [[#CodeRange]], a [[#CodeRange]].
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sdknso copies data from an user-buffer to the tmp [[#Struct32]] which is used with the cmd, the size of that user-buffer is passed as the cmd input u32.
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An error is thrown if the funcptr in state for the "nnjitpluginGenerateCode" symbol is not set.
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This does a bunch of validation. Then eventually CodeMemory/TransferMemory is mapped, the above symbol funcptr is called, runs more validation, and unmaps CodeMemory/TransferMemory. On success, this runs cache operations. Then this returns.
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The funcptr is called with the following params: x0 = s32* out, x1 = {ptr to output [[#CodeRange]] initialized with the input [[#CodeRange]] and with the second u64 cleared}, x2 = {ptr to output [[#CodeRange]] initialized with the input [[#CodeRange]] and with the second u64 cleared}, x3 = {ptr to struct on stack which is the same as the one used for the "nnjitpluginOnPrepared" symbol, except +0x30/+0x38 are set to the sysmodule map-addr for each CodeMemory (addr for the second CodeMemory is set properly)}, x4 = cmd input u64, x5 = InBuffer addr, x6 = InBuffer size, x7 = {ptr to input [[#CodeRange]]}, sp0 = {ptr to input [[#CodeRange]]}, sp8 = {ptr to input [[#Struct32]]}, sp16 = cmd input u32, sp24 = OutBuffer addr, sp32 = OutBuffer size.
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The input/output [[#CodeRange]] structs are validated as follows, where stateval is the first/second CodeMemory [[#CreateJitEnvironment|size]] for the first/second [[#CodeRange]]:
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* CodeRange.offset must be 0x4-byte aligned.
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* CodeRange.offset must be <= stateval-CodeRange.size.
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* stateval must be >= CodeRange.size.
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* CodeRange.size must be <= ~CodeRange.offset.
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* CodeRange.size must be 0x4-byte aligned.
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The output [[#CodeRange]] structs are validated the same way as the corresponding input [[#CodeRange]] structs, however in addition the output structs are validated against the input structs:
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* out_CodeRange.offset must be >= in_CodeRange.offset.
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* in_CodeRange.size must be >= out_CodeRange.size.
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* (out_CodeRange.offset-in_CodeRange.offset) must be <= (in_CodeRange.size-out_CodeRange.size).
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After using the cmd, sdknso runs cache operations.
    
== Control ==
 
== Control ==
 
Takes an input u64, a type-0x5 input buffer, a type-0x6 output buffer, and returns an output s32.
 
Takes an input u64, a type-0x5 input buffer, a type-0x6 output buffer, and returns an output s32.
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An error is thrown if the funcptr in state for the "nnjitpluginControl" symbol is not set.
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The TransferMemory is mapped, then the symbol funcptr is called: x0 = s32* out, x1 = {ptr to struct on stack which is the same as the one used for the "nnjitpluginOnPrepared" symbol}, x2 = {input u64 from the cmd}, x3/x4 = {cmd inbuffer addr/size}, x5/x6 = {cmd outbuffer addr/size}. Non-zero ret indicates error. On success the s32 from here is written to the cmd output s32. Afterwards, the TransferMemory is unmapped, then this returns.
    
== LoadPlugin ==
 
== LoadPlugin ==
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* "nnjitpluginSetupDiagnostics", this is optional. When successful and the funcptr is valid, this is called with w0=1 and x1 = {ptr to a funcptr on stack, the func for this is a duplicate of the one referenced above}.
 
* "nnjitpluginSetupDiagnostics", this is optional. When successful and the funcptr is valid, this is called with w0=1 and x1 = {ptr to a funcptr on stack, the func for this is a duplicate of the one referenced above}.
 
* "nnjitpluginConfigure", error is handled on failure. When [[Settings_services#GetDebugModeFlag|GetDebugModeFlag]] returns true, the symbol funcptr is called with x0 = {ptr where 2 output u32s are located}, and then the two output u32s are loaded (that data on stack is cleared prior to calling the funcptr). Otherwise when false, it's called with x0=0 and the fields which would contain the output u32s are cleared to 0. These fields are "nn::jit::MemorySecurityMode".
 
* "nnjitpluginConfigure", error is handled on failure. When [[Settings_services#GetDebugModeFlag|GetDebugModeFlag]] returns true, the symbol funcptr is called with x0 = {ptr where 2 output u32s are located}, and then the two output u32s are loaded (that data on stack is cleared prior to calling the funcptr). Otherwise when false, it's called with x0=0 and the fields which would contain the output u32s are cleared to 0. These fields are "nn::jit::MemorySecurityMode".
* {calls a vtable funcptr, and handles error on failure}
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* The symbol for "nnjitpluginControl" is loaded, with the funcptr copied into state. On success, the same is done with "nnjitpluginGenerateCode". If either of these fail, error handling will run.
 
* TransferMemory init is done here. An ASLR'd address for the TransferMemory mapped-address is determined, which will then be reused for all later mappings.
 
* TransferMemory init is done here. An ASLR'd address for the TransferMemory mapped-address is determined, which will then be reused for all later mappings.
 
* CodeMemory init func-calling is done for both regions, where w1={first output from "nnjitpluginConfigure" above}. Likewise with the TransferMemory, with w1={second output from "nnjitpluginConfigure" above}.
 
* CodeMemory init func-calling is done for both regions, where w1={first output from "nnjitpluginConfigure" above}. Likewise with the TransferMemory, with w1={second output from "nnjitpluginConfigure" above}.
* "nnjitpluginOnPrepared", error is handled on failure. Before/after calling this symbol funcptr, the TransferMemory is mapped/unmapped. The symbol funcptr is called with x0 = {ptr to struct on stack}. The struct has following structure: +0 = 0x20-bytes of data from state, +0x20 = TransferMemory map-addr, +0x28 = TransferMemory size, and +0x30 size 0x10-bytes is cleared.
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* "nnjitpluginOnPrepared", error is handled on failure. Before/after calling this symbol funcptr, the TransferMemory is mapped/unmapped. The symbol funcptr is called with x0 = {ptr to struct on stack}. The struct has following structure: +0 = 0x20-bytes of data from state {user-process map-addr/size for each CodeMemory, used by [[#GetCodeAddress]]}, +0x20 = TransferMemory map-addr, +0x28 = TransferMemory size, and +0x30 size 0x10-bytes is cleared.
 
* Then this does cleanup and returns.
 
* Then this does cleanup and returns.
    
== GetCodeAddress ==
 
== GetCodeAddress ==
 
No input, returns two output u64s which are loaded from state.
 
No input, returns two output u64s which are loaded from state.
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These u64s are the user-process map-addrs for each CodeMemory from [[#CreateJitEnvironment|state]]. Originally the second addr was a duplicate of the first addr, this was [[Switch_System_Flaws|fixed]] with [14.0.0+].
    
== CodeRange ==
 
== CodeRange ==
 
This is "nn::jit::CodeRange". This is a 0x10-byte struct. This is 8-byte aligned.
 
This is "nn::jit::CodeRange". This is a 0x10-byte struct. This is 8-byte aligned.
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{| class="wikitable" border="1"
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|-
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! Offset
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! Size
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! Description
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|-
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| 0x0 || 0x8 || Offset
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|-
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| 0x8 || 0x8 || Size
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|}
    
== Struct32 ==
 
== Struct32 ==
 
This is "nn::jitsrv::Struct32". This is a 0x20-byte struct. This is 8-byte aligned.
 
This is "nn::jitsrv::Struct32". This is a 0x20-byte struct. This is 8-byte aligned.
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This contains arbitrary plugin-specific input data which is passed to the [[#GenerateCode]] funcptr.
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= Title usage =
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There are no system-titles using jit:u. The only titles using it are the following:
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* [[Super Mario 3D All-Stars]] (N64 emulation only)
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* [[Nintendo 64 - Nintendo Switch Online]]