linux-stable/include/uapi/asm-generic/siginfo.h
Marco Elver 78ed93d72d signal: Deliver SIGTRAP on perf event asynchronously if blocked
With SIGTRAP on perf events, we have encountered termination of
processes due to user space attempting to block delivery of SIGTRAP.
Consider this case:

    <set up SIGTRAP on a perf event>
    ...
    sigset_t s;
    sigemptyset(&s);
    sigaddset(&s, SIGTRAP | <and others>);
    sigprocmask(SIG_BLOCK, &s, ...);
    ...
    <perf event triggers>

When the perf event triggers, while SIGTRAP is blocked, force_sig_perf()
will force the signal, but revert back to the default handler, thus
terminating the task.

This makes sense for error conditions, but not so much for explicitly
requested monitoring. However, the expectation is still that signals
generated by perf events are synchronous, which will no longer be the
case if the signal is blocked and delivered later.

To give user space the ability to clearly distinguish synchronous from
asynchronous signals, introduce siginfo_t::si_perf_flags and
TRAP_PERF_FLAG_ASYNC (opted for flags in case more binary information is
required in future).

The resolution to the problem is then to (a) no longer force the signal
(avoiding the terminations), but (b) tell user space via si_perf_flags
if the signal was synchronous or not, so that such signals can be
handled differently (e.g. let user space decide to ignore or consider
the data imprecise).

The alternative of making the kernel ignore SIGTRAP on perf events if
the signal is blocked may work for some usecases, but likely causes
issues in others that then have to revert back to interception of
sigprocmask() (which we want to avoid). [ A concrete example: when using
breakpoint perf events to track data-flow, in a region of code where
signals are blocked, data-flow can no longer be tracked accurately.
When a relevant asynchronous signal is received after unblocking the
signal, the data-flow tracking logic needs to know its state is
imprecise. ]

Fixes: 97ba62b278 ("perf: Add support for SIGTRAP on perf events")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Link: https://lore.kernel.org/r/20220404111204.935357-1-elver@google.com
2022-04-22 12:14:05 +02:00

360 lines
11 KiB
C

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _UAPI_ASM_GENERIC_SIGINFO_H
#define _UAPI_ASM_GENERIC_SIGINFO_H
#include <linux/compiler.h>
#include <linux/types.h>
typedef union sigval {
int sival_int;
void __user *sival_ptr;
} sigval_t;
#define SI_MAX_SIZE 128
/*
* The default "si_band" type is "long", as specified by POSIX.
* However, some architectures want to override this to "int"
* for historical compatibility reasons, so we allow that.
*/
#ifndef __ARCH_SI_BAND_T
#define __ARCH_SI_BAND_T long
#endif
#ifndef __ARCH_SI_CLOCK_T
#define __ARCH_SI_CLOCK_T __kernel_clock_t
#endif
#ifndef __ARCH_SI_ATTRIBUTES
#define __ARCH_SI_ATTRIBUTES
#endif
/*
* Be careful when extending this union. On 32bit siginfo_t is 32bit
* aligned. Which means that a 64bit field or any other field that
* would increase the alignment of siginfo_t will break the ABI.
*/
union __sifields {
/* kill() */
struct {
__kernel_pid_t _pid; /* sender's pid */
__kernel_uid32_t _uid; /* sender's uid */
} _kill;
/* POSIX.1b timers */
struct {
__kernel_timer_t _tid; /* timer id */
int _overrun; /* overrun count */
sigval_t _sigval; /* same as below */
int _sys_private; /* not to be passed to user */
} _timer;
/* POSIX.1b signals */
struct {
__kernel_pid_t _pid; /* sender's pid */
__kernel_uid32_t _uid; /* sender's uid */
sigval_t _sigval;
} _rt;
/* SIGCHLD */
struct {
__kernel_pid_t _pid; /* which child */
__kernel_uid32_t _uid; /* sender's uid */
int _status; /* exit code */
__ARCH_SI_CLOCK_T _utime;
__ARCH_SI_CLOCK_T _stime;
} _sigchld;
/* SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT */
struct {
void __user *_addr; /* faulting insn/memory ref. */
#ifdef __ia64__
int _imm; /* immediate value for "break" */
unsigned int _flags; /* see ia64 si_flags */
unsigned long _isr; /* isr */
#endif
#define __ADDR_BND_PKEY_PAD (__alignof__(void *) < sizeof(short) ? \
sizeof(short) : __alignof__(void *))
union {
/* used on alpha and sparc */
int _trapno; /* TRAP # which caused the signal */
/*
* used when si_code=BUS_MCEERR_AR or
* used when si_code=BUS_MCEERR_AO
*/
short _addr_lsb; /* LSB of the reported address */
/* used when si_code=SEGV_BNDERR */
struct {
char _dummy_bnd[__ADDR_BND_PKEY_PAD];
void __user *_lower;
void __user *_upper;
} _addr_bnd;
/* used when si_code=SEGV_PKUERR */
struct {
char _dummy_pkey[__ADDR_BND_PKEY_PAD];
__u32 _pkey;
} _addr_pkey;
/* used when si_code=TRAP_PERF */
struct {
unsigned long _data;
__u32 _type;
__u32 _flags;
} _perf;
};
} _sigfault;
/* SIGPOLL */
struct {
__ARCH_SI_BAND_T _band; /* POLL_IN, POLL_OUT, POLL_MSG */
int _fd;
} _sigpoll;
/* SIGSYS */
struct {
void __user *_call_addr; /* calling user insn */
int _syscall; /* triggering system call number */
unsigned int _arch; /* AUDIT_ARCH_* of syscall */
} _sigsys;
};
#ifndef __ARCH_HAS_SWAPPED_SIGINFO
#define __SIGINFO \
struct { \
int si_signo; \
int si_errno; \
int si_code; \
union __sifields _sifields; \
}
#else
#define __SIGINFO \
struct { \
int si_signo; \
int si_code; \
int si_errno; \
union __sifields _sifields; \
}
#endif /* __ARCH_HAS_SWAPPED_SIGINFO */
typedef struct siginfo {
union {
__SIGINFO;
int _si_pad[SI_MAX_SIZE/sizeof(int)];
};
} __ARCH_SI_ATTRIBUTES siginfo_t;
/*
* How these fields are to be accessed.
*/
#define si_pid _sifields._kill._pid
#define si_uid _sifields._kill._uid
#define si_tid _sifields._timer._tid
#define si_overrun _sifields._timer._overrun
#define si_sys_private _sifields._timer._sys_private
#define si_status _sifields._sigchld._status
#define si_utime _sifields._sigchld._utime
#define si_stime _sifields._sigchld._stime
#define si_value _sifields._rt._sigval
#define si_int _sifields._rt._sigval.sival_int
#define si_ptr _sifields._rt._sigval.sival_ptr
#define si_addr _sifields._sigfault._addr
#define si_trapno _sifields._sigfault._trapno
#define si_addr_lsb _sifields._sigfault._addr_lsb
#define si_lower _sifields._sigfault._addr_bnd._lower
#define si_upper _sifields._sigfault._addr_bnd._upper
#define si_pkey _sifields._sigfault._addr_pkey._pkey
#define si_perf_data _sifields._sigfault._perf._data
#define si_perf_type _sifields._sigfault._perf._type
#define si_perf_flags _sifields._sigfault._perf._flags
#define si_band _sifields._sigpoll._band
#define si_fd _sifields._sigpoll._fd
#define si_call_addr _sifields._sigsys._call_addr
#define si_syscall _sifields._sigsys._syscall
#define si_arch _sifields._sigsys._arch
/*
* si_code values
* Digital reserves positive values for kernel-generated signals.
*/
#define SI_USER 0 /* sent by kill, sigsend, raise */
#define SI_KERNEL 0x80 /* sent by the kernel from somewhere */
#define SI_QUEUE -1 /* sent by sigqueue */
#define SI_TIMER -2 /* sent by timer expiration */
#define SI_MESGQ -3 /* sent by real time mesq state change */
#define SI_ASYNCIO -4 /* sent by AIO completion */
#define SI_SIGIO -5 /* sent by queued SIGIO */
#define SI_TKILL -6 /* sent by tkill system call */
#define SI_DETHREAD -7 /* sent by execve() killing subsidiary threads */
#define SI_ASYNCNL -60 /* sent by glibc async name lookup completion */
#define SI_FROMUSER(siptr) ((siptr)->si_code <= 0)
#define SI_FROMKERNEL(siptr) ((siptr)->si_code > 0)
/*
* SIGILL si_codes
*/
#define ILL_ILLOPC 1 /* illegal opcode */
#define ILL_ILLOPN 2 /* illegal operand */
#define ILL_ILLADR 3 /* illegal addressing mode */
#define ILL_ILLTRP 4 /* illegal trap */
#define ILL_PRVOPC 5 /* privileged opcode */
#define ILL_PRVREG 6 /* privileged register */
#define ILL_COPROC 7 /* coprocessor error */
#define ILL_BADSTK 8 /* internal stack error */
#define ILL_BADIADDR 9 /* unimplemented instruction address */
#define __ILL_BREAK 10 /* illegal break */
#define __ILL_BNDMOD 11 /* bundle-update (modification) in progress */
#define NSIGILL 11
/*
* SIGFPE si_codes
*/
#define FPE_INTDIV 1 /* integer divide by zero */
#define FPE_INTOVF 2 /* integer overflow */
#define FPE_FLTDIV 3 /* floating point divide by zero */
#define FPE_FLTOVF 4 /* floating point overflow */
#define FPE_FLTUND 5 /* floating point underflow */
#define FPE_FLTRES 6 /* floating point inexact result */
#define FPE_FLTINV 7 /* floating point invalid operation */
#define FPE_FLTSUB 8 /* subscript out of range */
#define __FPE_DECOVF 9 /* decimal overflow */
#define __FPE_DECDIV 10 /* decimal division by zero */
#define __FPE_DECERR 11 /* packed decimal error */
#define __FPE_INVASC 12 /* invalid ASCII digit */
#define __FPE_INVDEC 13 /* invalid decimal digit */
#define FPE_FLTUNK 14 /* undiagnosed floating-point exception */
#define FPE_CONDTRAP 15 /* trap on condition */
#define NSIGFPE 15
/*
* SIGSEGV si_codes
*/
#define SEGV_MAPERR 1 /* address not mapped to object */
#define SEGV_ACCERR 2 /* invalid permissions for mapped object */
#define SEGV_BNDERR 3 /* failed address bound checks */
#ifdef __ia64__
# define __SEGV_PSTKOVF 4 /* paragraph stack overflow */
#else
# define SEGV_PKUERR 4 /* failed protection key checks */
#endif
#define SEGV_ACCADI 5 /* ADI not enabled for mapped object */
#define SEGV_ADIDERR 6 /* Disrupting MCD error */
#define SEGV_ADIPERR 7 /* Precise MCD exception */
#define SEGV_MTEAERR 8 /* Asynchronous ARM MTE error */
#define SEGV_MTESERR 9 /* Synchronous ARM MTE exception */
#define NSIGSEGV 9
/*
* SIGBUS si_codes
*/
#define BUS_ADRALN 1 /* invalid address alignment */
#define BUS_ADRERR 2 /* non-existent physical address */
#define BUS_OBJERR 3 /* object specific hardware error */
/* hardware memory error consumed on a machine check: action required */
#define BUS_MCEERR_AR 4
/* hardware memory error detected in process but not consumed: action optional*/
#define BUS_MCEERR_AO 5
#define NSIGBUS 5
/*
* SIGTRAP si_codes
*/
#define TRAP_BRKPT 1 /* process breakpoint */
#define TRAP_TRACE 2 /* process trace trap */
#define TRAP_BRANCH 3 /* process taken branch trap */
#define TRAP_HWBKPT 4 /* hardware breakpoint/watchpoint */
#define TRAP_UNK 5 /* undiagnosed trap */
#define TRAP_PERF 6 /* perf event with sigtrap=1 */
#define NSIGTRAP 6
/*
* There is an additional set of SIGTRAP si_codes used by ptrace
* that are of the form: ((PTRACE_EVENT_XXX << 8) | SIGTRAP)
*/
/*
* Flags for si_perf_flags if SIGTRAP si_code is TRAP_PERF.
*/
#define TRAP_PERF_FLAG_ASYNC (1u << 0)
/*
* SIGCHLD si_codes
*/
#define CLD_EXITED 1 /* child has exited */
#define CLD_KILLED 2 /* child was killed */
#define CLD_DUMPED 3 /* child terminated abnormally */
#define CLD_TRAPPED 4 /* traced child has trapped */
#define CLD_STOPPED 5 /* child has stopped */
#define CLD_CONTINUED 6 /* stopped child has continued */
#define NSIGCHLD 6
/*
* SIGPOLL (or any other signal without signal specific si_codes) si_codes
*/
#define POLL_IN 1 /* data input available */
#define POLL_OUT 2 /* output buffers available */
#define POLL_MSG 3 /* input message available */
#define POLL_ERR 4 /* i/o error */
#define POLL_PRI 5 /* high priority input available */
#define POLL_HUP 6 /* device disconnected */
#define NSIGPOLL 6
/*
* SIGSYS si_codes
*/
#define SYS_SECCOMP 1 /* seccomp triggered */
#define SYS_USER_DISPATCH 2 /* syscall user dispatch triggered */
#define NSIGSYS 2
/*
* SIGEMT si_codes
*/
#define EMT_TAGOVF 1 /* tag overflow */
#define NSIGEMT 1
/*
* sigevent definitions
*
* It seems likely that SIGEV_THREAD will have to be handled from
* userspace, libpthread transmuting it to SIGEV_SIGNAL, which the
* thread manager then catches and does the appropriate nonsense.
* However, everything is written out here so as to not get lost.
*/
#define SIGEV_SIGNAL 0 /* notify via signal */
#define SIGEV_NONE 1 /* other notification: meaningless */
#define SIGEV_THREAD 2 /* deliver via thread creation */
#define SIGEV_THREAD_ID 4 /* deliver to thread */
/*
* This works because the alignment is ok on all current architectures
* but we leave open this being overridden in the future
*/
#ifndef __ARCH_SIGEV_PREAMBLE_SIZE
#define __ARCH_SIGEV_PREAMBLE_SIZE (sizeof(int) * 2 + sizeof(sigval_t))
#endif
#define SIGEV_MAX_SIZE 64
#define SIGEV_PAD_SIZE ((SIGEV_MAX_SIZE - __ARCH_SIGEV_PREAMBLE_SIZE) \
/ sizeof(int))
typedef struct sigevent {
sigval_t sigev_value;
int sigev_signo;
int sigev_notify;
union {
int _pad[SIGEV_PAD_SIZE];
int _tid;
struct {
void (*_function)(sigval_t);
void *_attribute; /* really pthread_attr_t */
} _sigev_thread;
} _sigev_un;
} sigevent_t;
#define sigev_notify_function _sigev_un._sigev_thread._function
#define sigev_notify_attributes _sigev_un._sigev_thread._attribute
#define sigev_notify_thread_id _sigev_un._tid
#endif /* _UAPI_ASM_GENERIC_SIGINFO_H */