191 lines
5.2 KiB
ArmAsm
191 lines
5.2 KiB
ArmAsm
/**
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* Copyright (c) 2015-present, Facebook, Inc.
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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(__x86_64__)
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.globl SYMBOL_NAME(RCTProfileTrampoline)
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SYMBOL_NAME(RCTProfileTrampoline):
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/**
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* Saves all the state so we can restore it before calling the functions being
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* profiled. Registers have the same value at the point of the function call,
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* the only thing we can change is the return value, so we return to
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* `RCTProfileTrampoline` rather than to its caller.
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*
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* Save all the parameters registers (%rdi, %rsi, %rdx, %rcx, %r8, %r9), they
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* have the 6 first arguments of the function call, and %rax which in special
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* cases might be a pointer used for struct returns.
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*
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* We have to save %r12 since its value should be preserved across function
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* calls and we'll use it to keep the stack pointer
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*/
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subq $0x80+8, %rsp // 8 x 16-bytes xmm registers + 8-bytes alignment
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movdqa %xmm0, 0x70(%rsp)
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movdqa %xmm1, 0x60(%rsp)
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movdqa %xmm2, 0x50(%rsp)
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movdqa %xmm3, 0x40(%rsp)
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movdqa %xmm4, 0x30(%rsp)
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movdqa %xmm5, 0x20(%rsp)
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movdqa %xmm6, 0x10(%rsp)
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movdqa %xmm7, 0x00(%rsp)
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pushq %rdi
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pushq %rsi
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pushq %rdx
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pushq %rcx
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pushq %r8
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pushq %r9
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pushq %rax
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pushq %r12
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/**
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* Store the stack pointer in the callee saved register %r12 and align the
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* stack - it has to 16-byte aligned at the point of the function call
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*/
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movq %rsp, %r12
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andq $-0x10, %rsp
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/**
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* void RCTProfileGetImplementation(id object, SEL selector)
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*
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* This is a C function defined in `RCTProfile.m`, the object and the selector
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* already have to be on %rdi and %rsi respectively, as in any ObjC call.
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*/
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callq SYMBOL_NAME_PIC(RCTProfileGetImplementation)
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// Restore/unalign the stack pointer, so we can access the registers we stored
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movq %r12, %rsp
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/**
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* pop %r12 before pushing %rax, which contains the address of the actual
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* function we have to call, than we keep %r12 at the bottom of the stack to
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* reference the stack pointer
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*/
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popq %r12
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pushq %rax
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pushq %r12
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// align stack
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movq %rsp, %r12
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andq $-0x10, %rsp
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/**
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* Allocate memory to save parent before start profiling: the address is put
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* at the bottom of the stack at the function call, so ret can actually return
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* to the caller. In this case it has the address of RCTProfileTrampoline's
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* caller where we'll have to return to after we're finished.
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*
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* We can't store it on the stack or in any register, since we have to be in
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* the exact same state we were at the moment we were called, so the solution
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* is to allocate a tiny bit of memory to save this address
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*/
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// allocate 16 bytes
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movq $0x10, %rdi
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callq SYMBOL_NAME_PIC(RCTProfileMalloc)
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// store the initial value of calle saved registers %r13 and %r14
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movq %r13, 0x0(%rax)
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movq %r14, 0x8(%rax)
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// mov the pointers we need to the callee saved registers
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movq 0xd8(%rsp), %r13 // caller of RCTProfileTrampoline (0xd8 is stack top)
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movq %rax, %r14 // allocated memory's address
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/**
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* Move self and cmd back to the registers and call start profile: it uses
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* the object and the selector to label the call in the profile.
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*/
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movq 0x40(%r12), %rdi // object
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movq 0x38(%r12), %rsi // selector
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// void RCTProfileTrampolineStart(id, SEL) in RCTProfile.m
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callq SYMBOL_NAME_PIC(RCTProfileTrampolineStart)
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// unalign the stack and restore %r12
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movq %r12, %rsp
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popq %r12
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// Restore registers for actual function call
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popq %r11
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popq %rax
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popq %r9
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popq %r8
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popq %rcx
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popq %rdx
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popq %rsi
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popq %rdi
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movdqa 0x00(%rsp), %xmm7
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movdqa 0x10(%rsp), %xmm6
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movdqa 0x20(%rsp), %xmm5
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movdqa 0x30(%rsp), %xmm4
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movdqa 0x40(%rsp), %xmm3
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movdqa 0x50(%rsp), %xmm2
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movdqa 0x60(%rsp), %xmm1
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movdqa 0x70(%rsp), %xmm0
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addq $0x80+8, %rsp
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/**
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* delete parent caller (saved in %r13) `call` will add the new address so
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* we return to RCTProfileTrampoline rather than to its caller
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*/
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addq $0x8, %rsp
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// call the actual function and save the return value
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callq *%r11
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pushq %rax
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pushq %rdx
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subq $0x20, %rsp // 2 16-bytes xmm register
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movdqa %xmm0, 0x00(%rsp)
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movdqa %xmm1, 0x10(%rsp)
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// void RCTProfileTrampolineEnd(void) in RCTProfile.m - just ends this profile
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callq SYMBOL_NAME_PIC(RCTProfileTrampolineEnd)
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/**
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* Restore the initial value of the callee saved registers, saved in the
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* memory allocated.
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*/
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movq %r13, %rcx
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movq %r14, %rdi
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movq 0x0(%r14), %r13
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movq 0x8(%r14), %r14
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/**
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* save caller address and actual function return (previously in the allocated
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* memory) and align the stack
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*/
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pushq %rcx
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pushq %r12
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movq %rsp, %r12
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andq $-0x10, %rsp
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// Free the memory allocated to stash callee saved registers
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callq SYMBOL_NAME_PIC(RCTProfileFree)
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// unalign stack and restore %r12
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movq %r12, %rsp
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popq %r12
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/**
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* pop the caller address to %rcx and the actual function return value(s)
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* so it's the return value of RCTProfileTrampoline
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*/
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popq %rcx
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movdqa 0x00(%rsp), %xmm0
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movdqa 0x10(%rsp), %xmm1
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addq $0x20, %rsp
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popq %rdx
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popq %rax
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// jump to caller
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jmpq *%rcx
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#endif
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