AuroraMiddleware/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2024-12-09 21:01:05 +00:00
Code Issues Packages Projects Releases Wiki Activity
915b9fe312
glibc/sysdeps/unix/sysv/linux/sys/rseq.h
Mathieu Desnoyers 0c76fc3c2b Linux: Perform rseq registration at C startup and thread creation 
Register rseq TLS for each thread (including main), and unregister for
each thread (excluding main).  "rseq" stands for Restartable Sequences.

See the rseq(2) man page proposed here:
  https://lkml.org/lkml/2018/9/19/647

Those are based on glibc master branch commit 3ee1e0ec5c.
The rseq system call was merged into Linux 4.18.

The TLS_STATIC_SURPLUS define is increased to leave additional room for
dlopen'd initial-exec TLS, which keeps elf/tst-auditmany working.

The increase (76 bytes) is larger than 32 bytes because it has not been
increased in quite a while.  The cost in terms of additional TLS storage
is quite significant, but it will also obscure some initial-exec-related
dlopen failures.
2020-07-06 10:21:16 +02:00

204 lines
7.3 KiB
C
Raw Blame History

/* Restartable Sequences exported symbols. Linux header.
Copyright (C) 2020 Free Software Foundation, Inc.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#ifndef _SYS_RSEQ_H
#define _SYS_RSEQ_H 1
/* Architecture-specific rseq signature. */
#include <bits/rseq.h>
#include <stdint.h>
#include <sys/cdefs.h>
#ifdef __has_include
# if __has_include ("linux/rseq.h")
# define __GLIBC_HAVE_KERNEL_RSEQ
# endif
#else
# include <linux/version.h>
# if LINUX_VERSION_CODE >= KERNEL_VERSION (4, 18, 0)
# define __GLIBC_HAVE_KERNEL_RSEQ
# endif
#endif
/* Rely on GNU extensions for older standards and tls model. */
#ifdef __GNUC__
# define __rseq_tls_model_ie __attribute__ ((__tls_model__ ("initial-exec")))
#else
/* Specifying the TLS model on the declaration is optional. */
# define __rseq_tls_model_ie /* Nothing. */
#endif
#ifdef __cplusplus
# if __cplusplus >= 201103L
# define __rseq_tls_storage_class thread_local
# endif
#elif (defined __STDC_VERSION__ ? __STDC_VERSION__ : 0) >= 201112L
# define __rseq_tls_storage_class _Thread_local
#endif
/* Fall back to __thread for TLS storage class. */
#ifndef __rseq_tls_storage_class
# define __rseq_tls_storage_class __thread
#endif
#ifdef __GLIBC_HAVE_KERNEL_RSEQ
/* We use the structures declarations from the kernel headers. */
# include <linux/rseq.h>
#else /* __GLIBC_HAVE_KERNEL_RSEQ */
/* We use a copy of the include/uapi/linux/rseq.h kernel header. */
# include <asm/byteorder.h>
enum rseq_cpu_id_state
{
RSEQ_CPU_ID_UNINITIALIZED = -1,
RSEQ_CPU_ID_REGISTRATION_FAILED = -2,
};
enum rseq_flags
{
RSEQ_FLAG_UNREGISTER = (1 << 0),
};
enum rseq_cs_flags_bit
{
RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT = 0,
RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT = 1,
RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT = 2,
};
enum rseq_cs_flags
{
RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT =
(1U << RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT_BIT),
RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL =
(1U << RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL_BIT),
RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE =
(1U << RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE_BIT),
};
/* struct rseq_cs is aligned on 32 bytes to ensure it is always
contained within a single cache-line. It is usually declared as
link-time constant data. */
struct rseq_cs
{
/* Version of this structure. */
uint32_t version;
/* enum rseq_cs_flags. */
uint32_t flags;
uint64_t start_ip;
/* Offset from start_ip. */
uint64_t post_commit_offset;
uint64_t abort_ip;
} __attribute__ ((__aligned__ (32)));
/* struct rseq is aligned on 32 bytes to ensure it is always
contained within a single cache-line.
A single struct rseq per thread is allowed. */
struct rseq
{
/* Restartable sequences cpu_id_start field. Updated by the
kernel. Read by user-space with single-copy atomicity
semantics. This field should only be read by the thread which
registered this data structure. Aligned on 32-bit. Always
contains a value in the range of possible CPUs, although the
value may not be the actual current CPU (e.g. if rseq is not
initialized). This CPU number value should always be compared
against the value of the cpu_id field before performing a rseq
commit or returning a value read from a data structure indexed
using the cpu_id_start value. */
uint32_t cpu_id_start;
/* Restartable sequences cpu_id field. Updated by the kernel.
Read by user-space with single-copy atomicity semantics. This
field should only be read by the thread which registered this
data structure. Aligned on 32-bit. Values
RSEQ_CPU_ID_UNINITIALIZED and RSEQ_CPU_ID_REGISTRATION_FAILED
have a special semantic: the former means "rseq uninitialized",
and latter means "rseq initialization failed". This value is
meant to be read within rseq critical sections and compared
with the cpu_id_start value previously read, before performing
the commit instruction, or read and compared with the
cpu_id_start value before returning a value loaded from a data
structure indexed using the cpu_id_start value. */
uint32_t cpu_id;
/* Restartable sequences rseq_cs field.
Contains NULL when no critical section is active for the current
thread, or holds a pointer to the currently active struct rseq_cs.
Updated by user-space, which sets the address of the currently
active rseq_cs at the beginning of assembly instruction sequence
block, and set to NULL by the kernel when it restarts an assembly
instruction sequence block, as well as when the kernel detects that
it is preempting or delivering a signal outside of the range
targeted by the rseq_cs. Also needs to be set to NULL by user-space
before reclaiming memory that contains the targeted struct rseq_cs.
Read and set by the kernel. Set by user-space with single-copy
atomicity semantics. This field should only be updated by the
thread which registered this data structure. Aligned on 64-bit. */
union
{
uint64_t ptr64;
# ifdef __LP64__
uint64_t ptr;
# else /* __LP64__ */
struct
{
# if (defined (__BYTE_ORDER) && (__BYTE_ORDER == __BIG_ENDIAN)) || defined (__BIG_ENDIAN)
uint32_t padding; /* Initialized to zero. */
uint32_t ptr32;
# else /* LITTLE */
uint32_t ptr32;
uint32_t padding; /* Initialized to zero. */
# endif /* ENDIAN */
} ptr;
# endif /* __LP64__ */
} rseq_cs;
/* Restartable sequences flags field.
This field should only be updated by the thread which
registered this data structure. Read by the kernel.
Mainly used for single-stepping through rseq critical sections
with debuggers.
- RSEQ_CS_FLAG_NO_RESTART_ON_PREEMPT
Inhibit instruction sequence block restart on preemption
for this thread.
- RSEQ_CS_FLAG_NO_RESTART_ON_SIGNAL
Inhibit instruction sequence block restart on signal
delivery for this thread.
- RSEQ_CS_FLAG_NO_RESTART_ON_MIGRATE
Inhibit instruction sequence block restart on migration for
this thread. */
uint32_t flags;
} __attribute__ ((__aligned__ (32)));
#endif /* __GLIBC_HAVE_KERNEL_RSEQ */
/* Allocations of struct rseq and struct rseq_cs on the heap need to
be aligned on 32 bytes. Therefore, use of malloc is discouraged
because it does not guarantee alignment. posix_memalign should be
used instead. */
extern __rseq_tls_storage_class struct rseq __rseq_abi __rseq_tls_model_ie;
#endif /* sys/rseq.h */
Reference in New Issue View Git Blame Copy Permalink