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https://github.com/jart/cosmopolitan.git
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eb40cb371d
This change implements a new approach to function call logging, that's based on the GCC flag: -fpatchable-function-entry. Read the commentary in build/config.mk to learn how it works.
100 lines
2.3 KiB
C
100 lines
2.3 KiB
C
#ifndef COSMOPOLITAN_LIBC_SYSV_MACROS_H_
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#define COSMOPOLITAN_LIBC_SYSV_MACROS_H_
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#include "libc/macros.internal.h"
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#ifdef __ASSEMBLER__
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/* clang-format off */
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/**
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* @fileoverview System Five jump slot generator.
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*
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* We need to pass a magic number to the SYSCALL instruction in %rax.
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* That's only possible to do in C using asm() macro wrappers, like in
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* Chromium's "System Call Support" library. This technique is simpler
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* to implement, gains us object-level ABI compatibility, hookability,
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* and the ability to support significantly more functions, without the
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* risk of slowing down builds too much with complicated headers.
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*/
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.macro .scall name:req amd:req arm_linux:req arm_xnu:req kw1 kw2
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.section .text.syscall,"ax",@progbits
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#ifdef __x86_64__
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.ifnb \kw2
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.ftrace1
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\name: .ftrace2
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movabs $\amd,%rax
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jmp *__systemfive(%rip)
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.else
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.ftrace1
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\name: .ftrace2
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push %rbp
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mov %rsp,%rbp
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movabs $\amd,%rax
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call *__systemfive(%rip)
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pop %rbp
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ret
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.endif
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.endfn \name,\kw1,\kw2
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#elif defined(__aarch64__)
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.ifc \arm_linux,4095
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.ifc \arm_xnu,4095
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// return enosys();
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.ftrace1
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\name: .ftrace2
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b enosys
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.endfn \name,\kw1,\kw2
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.else
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// return IsXnu() ? syscall(x16, ...) : syscall(x8, ...);
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.ftrace1
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\name: .ftrace2
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adrp x9,__hostos
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ldr w9,[x9,#:lo12:__hostos]
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tbz x9,#3,1f // !IsXnu()
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mov x16,#\arm_xnu // apple ordinal
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svc #0 // issue system call
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bcs 1f
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b _sysret
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1: neg x0,x0
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b _sysret
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.hidden _sysret
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.endfn \name,\kw1,\kw2
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.endif
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.else
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.ifc \arm_xnu,4095
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// return IsLinux() ? syscall(x8, ...) : enosys();
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.ftrace1
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\name: .ftrace2
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adrp x9,__hostos
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ldr w9,[x9,#:lo12:__hostos]
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tbz x9,#0,1f // !IsLinux()
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mov x8,#\arm_linux // systemd ordinal
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svc #0 // issue system call
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mov x1,#\arm_linux
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b _sysret
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.hidden _sysret
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1: b enosys
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.endfn \name,\kw1,\kw2
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.else
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.ftrace1
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\name: .ftrace2
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mov x16,#\arm_xnu // apple ordinal
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mov x8,#\arm_linux // systemd ordinal
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mov x9,#0 // clear carry flag
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adds x9,x9,#0 // clear carry flag
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svc #0 // issue system call
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bcs 1f
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b _sysret
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1: neg x0,x0
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b _sysret
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.hidden _sysret
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.endfn \name,\kw1,\kw2
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.endif
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.endif
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#else
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#error "architecture unsupported"
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#endif
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.previous
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.endm
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/* clang-format on */
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#endif /* __ASSEMBLER__ */
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#endif /* COSMOPOLITAN_LIBC_SYSV_MACROS_H_ */
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