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emacs/exec/exec.h
Po Lu ebf5bcb9f0 Optimize process execution on Android
* exec/configure.ac (REENTRANT): Remove option for reentrancy.
(PROGRAM_COUNTER, HAVE_SECCOMP): Define register providing the
program counter and enable seccomp if its headers are available.

* exec/exec.c (write_load_command): Avoid defining unused
variable.
(exec_0): Remove code specific to REENTRANT configurations.

* exec/exec.h (struct exec_tracee) <exec_data, data_size>: New
fields for loader instructions and their size.

* exec/exec1.c (main): Call exec_init before forking.

* exec/mipsel-user.h (ELF_NGREG): Delete definition.
(struct mipsel_regs): Reduce number of gregs to 32, but
introduce separate fields for special registers.

* exec/trace.c (use_seccomp_p): New variable; defile to false if
!HAVE_SECCOMP.
(remove_tracee): Cease providing for non-reentrant
configurations.  Release executable data if present.
(handle_clone_prepare): Likewise.  Resume process with
PTRACE_CONT if seccomp-based interception is enabled.
(handle_clone, check_signal): Resume processes as above.
(handle_exec): Divide into two functions, with only rewriting
the system call and generating instructions for the loader
remaining in the first, and copying such instructions into the
loader's stack removed into a new function, `finish_exec'.
(finish_exec): New function.
(handle_readlinkat, handle_openat): Abolish non-REENTRANT
configurations.
(process_system_call): Divide exec system calls into two phases,
disambiguated by the value of tracee->waiting_for_syscall.  Typo
fixes.  Accommodate syscall-exit-stops where the signal was
initially intercepted by `seccomp_system_call'.
(interesting_syscalls): New array.
(ARRAYELTS): New macro.
(seccomp_system_call, establish_seccomp_filter): New function.
(tracing_execve) [HAVE_SECCOMP]: Establish a seccomp filter if
this is to be enabled.
(after_fork): Provide PTRACE_O_TRACESECCOMP.  Resume process
with PTRACE_CONT if seccomp-based interception is enabled.
(exec_waitpid): Resume process with PTRACE_CONT if seccomp-based
interception is enabled.  Dispatch stops identifying as
PTRACE_EVENT_SECCOMP to `seccomp_system_call'.
(exec_init): Establish whether it is possible to enable seccomp.
2024-07-01 18:11:58 +08:00

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/* Program execution for Emacs.
Copyright (C) 2023-2024 Free Software Foundation, Inc.
This file is part of GNU Emacs.
GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
#ifndef _EXEC_H_
#define _EXEC_H_
#ifdef HAVE_STDINT_H
#include <stdint.h>
#endif /* HAVE_STDINT_H */
#include <sys/types.h>
#include USER_HEADER
/* Define a replacement for `uint64_t' if it's not present in the C
library. */
#ifndef UINT64_MAX
typedef struct
{
uint32_t word1;
uint32_t word2;
} xint64_t;
#else /* UINT64_MAX */
typedef uint64_t xint64_t;
#endif /* !UINT64_MAX */
/* 32-bit ELF headers. */
struct elf_header_32
{
unsigned char e_ident[16];
uint16_t e_type;
uint16_t e_machine;
uint32_t e_version;
uint32_t e_entry;
uint32_t e_phoff;
uint32_t e_shoff;
uint32_t e_flags;
uint16_t e_ehsize;
uint16_t e_phentsize;
uint16_t e_phnum;
uint16_t e_shentsize;
uint16_t e_shnum;
uint16_t e_shstrndx;
};
struct program_header_32
{
uint32_t p_type;
uint32_t p_offset;
uint32_t p_vaddr;
uint32_t p_paddr;
uint32_t p_filesz;
uint32_t p_memsz;
uint32_t p_flags;
uint32_t p_align;
};
struct dt_entry_32
{
uint32_t d_tag;
uint32_t d_val;
};
struct elf_header_64
{
unsigned char e_ident[16];
uint16_t e_type;
uint16_t e_machine;
uint32_t e_version;
xint64_t e_entry;
xint64_t e_phoff;
xint64_t e_shoff;
uint32_t e_flags;
uint16_t e_ehsize;
uint16_t e_phentsize;
uint16_t e_phnum;
uint16_t e_shentsize;
uint16_t e_shnum;
uint16_t e_shstrndx;
};
struct program_header_64
{
uint32_t p_type;
uint32_t p_flags;
xint64_t p_offset;
xint64_t p_vaddr;
xint64_t p_paddr;
xint64_t p_filesz;
xint64_t p_memsz;
xint64_t p_align;
};
struct dt_entry_64
{
xint64_t d_tag;
xint64_t d_val;
};
/* Define some types to the correct values. */
#ifdef EXEC_64
typedef struct elf_header_64 elf_header;
typedef struct program_header_64 program_header;
typedef struct dt_entry_64 dt_entry;
#else /* !EXEC_64 */
typedef struct elf_header_32 elf_header;
typedef struct program_header_32 program_header;
typedef struct dt_entry_32 dt_entry;
#endif /* EXEC_64 */
/* Defined in trace.c. */
/* Structure describing a process being traced. */
struct exec_tracee
{
/* The next process being traced. */
struct exec_tracee *next;
/* Address of any stack pointer to restore after system call
completion. */
USER_WORD sp;
/* Name of the executable being run. */
char *exec_file;
/* Pointer to a storage area holding instructions for loading an
executable if an `exec' system call is outstanding, or NULL. */
char *exec_data;
/* Number of bytes in exec_data. */
size_t data_size;
/* The thread ID of this process. */
pid_t pid;
/* Whether or not the tracee is currently waiting for a system call
to complete. */
bool waiting_for_syscall : 1;
/* Whether or not the tracee has been created but is not yet
processed by `handle_clone'. */
bool new_child : 1;
};
#ifdef __aarch64__
extern int aarch64_get_regs (pid_t, USER_REGS_STRUCT *);
extern int aarch64_set_regs (pid_t, USER_REGS_STRUCT *, bool);
#endif /* __aarch64__ */
extern char *format_pid (char *, unsigned int);
extern USER_WORD user_alloca (struct exec_tracee *, USER_REGS_STRUCT *,
USER_REGS_STRUCT *, USER_WORD);
extern int user_copy (struct exec_tracee *, const unsigned char *,
USER_WORD, USER_WORD);
extern void exec_init (const char *);
extern int tracing_execve (const char *, char *const *,
char *const *);
extern int after_fork (pid_t);
extern pid_t exec_waitpid (pid_t, int *, int);
/* Defined in exec.c. */
extern char *exec_0 (char *, struct exec_tracee *,
size_t *, USER_REGS_STRUCT *);
#endif /* _EXEC_H_ */