97 lines
2.7 KiB
ArmAsm
97 lines
2.7 KiB
ArmAsm
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/**
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* Copyright (c) Meta Platforms, Inc. and affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*/
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#include "RCTDefines.h"
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#include "RCTMacros.h"
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#if RCT_PROFILE && defined(__arm__)
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.thumb
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.thumb_func
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.globl SYMBOL_NAME(RCTProfileTrampoline)
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SYMBOL_NAME(RCTProfileTrampoline):
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/**
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* The explanation here is shorter, refer to the x86_64 implementation to a
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* richer explanation
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*/
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/**
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* Save the parameter registers (r0-r3), r7 (frame pointer) and lr (link
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* register (contains the address of the caller of RCTProfileTrampoline)
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*/
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push {r0-r3, r7, lr}
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/**
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* Allocate memory to store values across function calls: 12-bytes are
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* allocated to store 3 values: the previous value of the callee saved
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* register used to save the pointer to the allocated memory, the caller of
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* RCTProfileTrampoline and the address of the actual function we want to
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* profile
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*/
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mov r0, #0xc
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bl SYMBOL_NAME(RCTProfileMalloc)
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/**
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* r4 is the callee saved register we'll use to refer to the allocated memory,
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* store its initial value, so we can restore it later
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*/
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str r4, [r0]
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mov r4, r0
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/**
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* void RCTProfileGetImplementation(id object, SEL selector) in RCTProfile.m
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*
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* Load the first 2 argumenters (self and _cmd) used to call
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* RCTProfileTrampoline from the stack and put them on the appropriate registers.
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*/
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ldr r0, [sp]
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ldr r1, [sp, #0x4]
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bl SYMBOL_NAME(RCTProfileGetImplementation)
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// store the actual function address in the allocated memory
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str r0, [r4, #0x4]
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/**
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* void RCTProfileGetImplementation(id object, SEL selector) in RCTProfile.m
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*
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* Load the first 2 arguments again to start the profiler
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*/
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ldr r0, [sp]
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ldr r1, [sp, #0x4]
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bl SYMBOL_NAME(RCTProfileTrampolineStart)
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/**
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* Restore the state to call the actual function we want to profile: pop
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* all the registers
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*/
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pop {r0-r3, r7, lr}
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// store lr (the caller) since it'll be overridden by `blx` (call)
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str lr, [r4, #0x8]
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ldr r12, [r4, #0x4] // load the function address
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blx r12 // call it
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push {r0} // save return value
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// void RCTProfileTrampolineEnd(void) in RCTProfile.m - just ends this profile
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bl SYMBOL_NAME(RCTProfileTrampolineEnd)
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/**
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* Save the value we still need from the allocated memory (caller address),
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* restore r4 and free the allocated memory (put its address in r0)
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*/
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mov r0, r4
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ldr r1, [r4, #0x8]
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ldr r4, [r4]
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push {r1} // save the caller on the stack
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bl SYMBOL_NAME(RCTProfileFree)
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pop {lr} // pop the caller
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pop {r0} // pop the return value
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bx lr // jump to the caller
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trap
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#endif
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