PR sanitizer/81923

[official-gcc.git] / libgo / runtime / go-signal.c

/* go-signal.c -- signal handling for Go.

   Copyright 2009 The Go Authors. All rights reserved.
   Use of this source code is governed by a BSD-style
   license that can be found in the LICENSE file.  */

#include <signal.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/time.h>
#include <ucontext.h>

#include "runtime.h"

#ifndef SA_RESTART
  #define SA_RESTART 0
#endif

#ifdef USING_SPLIT_STACK

extern void __splitstack_getcontext(void *context[10]);

extern void __splitstack_setcontext(void *context[10]);

extern void *__splitstack_find_context(void *context[10], size_t *,
                                       void **, void **, void **);

#endif

// The rest of the signal handler, written in Go.

extern void sigtrampgo(uint32, siginfo_t *, void *)
        __asm__(GOSYM_PREFIX "runtime.sigtrampgo");

// The Go signal handler, written in C.  This should be running on the
// alternate signal stack.  This is responsible for setting up the
// split stack context so that stack guard checks will work as
// expected.

void sigtramp(int, siginfo_t *, void *)
        __attribute__ ((no_split_stack));

void sigtramp(int, siginfo_t *, void *)
        __asm__ (GOSYM_PREFIX "runtime.sigtramp");

#ifndef USING_SPLIT_STACK

// When not using split stacks, there are no stack checks, and there
// is nothing special for this function to do.

void
sigtramp(int sig, siginfo_t *info, void *context)
{
        sigtrampgo(sig, info, context);
}

#else // USING_SPLIT_STACK

void
sigtramp(int sig, siginfo_t *info, void *context)
{
        G *gp;
        void *stack_context[10];
        void *stack;
        size_t stack_size;
        void *next_segment;
        void *next_sp;
        void *initial_sp;
        uintptr sp;
        stack_t st;
        uintptr stsp;

        gp = runtime_g();

        if (gp == nil) {
                // Let the Go code handle this case.
                // It should only call nosplit functions in this case.
                sigtrampgo(sig, info, context);
                return;
        }

        // If this signal is one for which we will panic, we are not
        // on the alternate signal stack.  It's OK to call split-stack
        // functions here.
        if (sig == SIGBUS || sig == SIGFPE || sig == SIGSEGV) {
                sigtrampgo(sig, info, context);
                return;
        }

        // We are running on the alternate signal stack.

        __splitstack_getcontext(&stack_context[0]);

        stack = __splitstack_find_context((void*)(&gp->m->gsignal->stackcontext[0]),
                                          &stack_size, &next_segment,
                                          &next_sp, &initial_sp);

        // If some non-Go code called sigaltstack, adjust.
        sp = (uintptr)(&stack_size);
        if (sp < (uintptr)(stack) || sp >= (uintptr)(stack) + stack_size) {
                sigaltstack(nil, &st);
                if ((st.ss_flags & SS_DISABLE) != 0) {
                        runtime_printf("signal %d received on thread with no signal stack\n", (int32)(sig));
                        runtime_throw("non-Go code disabled sigaltstack");
                }

                stsp = (uintptr)(st.ss_sp);
                if (sp < stsp || sp >= stsp + st.ss_size) {
                        runtime_printf("signal %d received but handler not on signal stack\n", (int32)(sig));
                        runtime_throw("non-Go code set up signal handler without SA_ONSTACK flag");
                }

                // Unfortunately __splitstack_find_context will return NULL
                // when it is called on a context that has never been used.
                // There isn't much we can do but assume all is well.
                if (stack != NULL) {
                        // Here the gc runtime adjusts the gsignal
                        // stack guard to match the values returned by
                        // sigaltstack.  Unfortunately we have no way
                        // to do that.
                        runtime_printf("signal %d received on unknown signal stack\n", (int32)(sig));
                        runtime_throw("non-Go code changed signal stack");
                }
        }

        // Set the split stack context so that the stack guards are
        // checked correctly.

        __splitstack_setcontext((void*)(&gp->m->gsignal->stackcontext[0]));

        sigtrampgo(sig, info, context);

        // We are going to return back to the signal trampoline and
        // then to whatever we were doing before we got the signal.
        // Restore the split stack context so that stack guards are
        // checked correctly.

        __splitstack_setcontext(&stack_context[0]);
}

#endif // USING_SPLIT_STACK

// C function to return the address of the sigtramp function.
uintptr getSigtramp(void) __asm__ (GOSYM_PREFIX "runtime.getSigtramp");

uintptr
getSigtramp()
{
  return (uintptr)(void*)sigtramp;
}

// C code to manage the sigaction sa_sigaction field, which is
// typically a union and so hard for mksysinfo.sh to handle.

uintptr getSigactionHandler(struct sigaction*)
        __attribute__ ((no_split_stack));

uintptr getSigactionHandler(struct sigaction*)
        __asm__ (GOSYM_PREFIX "runtime.getSigactionHandler");

uintptr
getSigactionHandler(struct sigaction* sa)
{
        return (uintptr)(sa->sa_sigaction);
}

void setSigactionHandler(struct sigaction*, uintptr)
        __attribute__ ((no_split_stack));

void setSigactionHandler(struct sigaction*, uintptr)
        __asm__ (GOSYM_PREFIX "runtime.setSigactionHandler");

void
setSigactionHandler(struct sigaction* sa, uintptr handler)
{
        sa->sa_sigaction = (void*)(handler);
}

// C code to fetch values from the siginfo_t and ucontext_t pointers
// passed to a signal handler.

struct getSiginfoRet {
        uintptr sigaddr;
        uintptr sigpc;
};

struct getSiginfoRet getSiginfo(siginfo_t *, void *)
        __asm__(GOSYM_PREFIX "runtime.getSiginfo");

struct getSiginfoRet
getSiginfo(siginfo_t *info, void *context __attribute__((unused)))
{
        struct getSiginfoRet ret;
        Location loc[1];
        int32 n;

        if (info == nil) {
                ret.sigaddr = 0;
        } else {
                ret.sigaddr = (uintptr)(info->si_addr);
        }
        ret.sigpc = 0;

        // There doesn't seem to be a portable way to get the PC.
        // Use unportable code to pull it from context, and if that fails
        // try a stack backtrace across the signal handler.

#ifdef __x86_64__
 #ifdef __linux__
        ret.sigpc = ((ucontext_t*)(context))->uc_mcontext.gregs[REG_RIP];
 #endif
#endif
#ifdef __i386__
  #ifdef __linux__
        ret.sigpc = ((ucontext_t*)(context))->uc_mcontext.gregs[REG_EIP];
  #endif
#endif
#ifdef __alpha__
  #ifdef __linux__
        ret.sigpc = ((ucontext_t*)(context))->uc_mcontext.sc_pc;
  #endif
#endif
#ifdef __PPC__
  #ifdef __linux__
        ret.sigpc = ((ucontext_t*)(context))->uc_mcontext.regs->nip;
  #endif
  #ifdef _AIX
        ret.sigpc = ((ucontext_t*)(context))->uc_mcontext.jmp_context.iar;
  #endif
#endif

        if (ret.sigpc == 0) {
                // Skip getSiginfo/sighandler/sigtrampgo/sigtramp/handler.
                n = runtime_callers(5, &loc[0], 1, false);
                if (n > 0) {
                        ret.sigpc = loc[0].pc;
                }
        }

        return ret;
}

// Dump registers when crashing in a signal.
// There is no portable way to write this,
// so we just have some CPU/OS specific implementations.

void dumpregs(siginfo_t *, void *)
        __asm__(GOSYM_PREFIX "runtime.dumpregs");

void
dumpregs(siginfo_t *info __attribute__((unused)), void *context __attribute__((unused)))
{
#ifdef __x86_64__
 #ifdef __linux__
        {
                mcontext_t *m = &((ucontext_t*)(context))->uc_mcontext;

                runtime_printf("rax    %X\n", m->gregs[REG_RAX]);
                runtime_printf("rbx    %X\n", m->gregs[REG_RBX]);
                runtime_printf("rcx    %X\n", m->gregs[REG_RCX]);
                runtime_printf("rdx    %X\n", m->gregs[REG_RDX]);
                runtime_printf("rdi    %X\n", m->gregs[REG_RDI]);
                runtime_printf("rsi    %X\n", m->gregs[REG_RSI]);
                runtime_printf("rbp    %X\n", m->gregs[REG_RBP]);
                runtime_printf("rsp    %X\n", m->gregs[REG_RSP]);
                runtime_printf("r8     %X\n", m->gregs[REG_R8]);
                runtime_printf("r9     %X\n", m->gregs[REG_R9]);
                runtime_printf("r10    %X\n", m->gregs[REG_R10]);
                runtime_printf("r11    %X\n", m->gregs[REG_R11]);
                runtime_printf("r12    %X\n", m->gregs[REG_R12]);
                runtime_printf("r13    %X\n", m->gregs[REG_R13]);
                runtime_printf("r14    %X\n", m->gregs[REG_R14]);
                runtime_printf("r15    %X\n", m->gregs[REG_R15]);
                runtime_printf("rip    %X\n", m->gregs[REG_RIP]);
                runtime_printf("rflags %X\n", m->gregs[REG_EFL]);
                runtime_printf("cs     %X\n", m->gregs[REG_CSGSFS] & 0xffff);
                runtime_printf("fs     %X\n", (m->gregs[REG_CSGSFS] >> 16) & 0xffff);
                runtime_printf("gs     %X\n", (m->gregs[REG_CSGSFS] >> 32) & 0xffff);
          }
 #endif
#endif

#ifdef __i386__
 #ifdef __linux__
        {
                mcontext_t *m = &((ucontext_t*)(context))->uc_mcontext;

                runtime_printf("eax    %x\n", m->gregs[REG_EAX]);
                runtime_printf("ebx    %x\n", m->gregs[REG_EBX]);
                runtime_printf("ecx    %x\n", m->gregs[REG_ECX]);
                runtime_printf("edx    %x\n", m->gregs[REG_EDX]);
                runtime_printf("edi    %x\n", m->gregs[REG_EDI]);
                runtime_printf("esi    %x\n", m->gregs[REG_ESI]);
                runtime_printf("ebp    %x\n", m->gregs[REG_EBP]);
                runtime_printf("esp    %x\n", m->gregs[REG_ESP]);
                runtime_printf("eip    %x\n", m->gregs[REG_EIP]);
                runtime_printf("eflags %x\n", m->gregs[REG_EFL]);
                runtime_printf("cs     %x\n", m->gregs[REG_CS]);
                runtime_printf("fs     %x\n", m->gregs[REG_FS]);
                runtime_printf("gs     %x\n", m->gregs[REG_GS]);
          }
 #endif
#endif

#ifdef __alpha__
  #ifdef __linux__
        {
                mcontext_t *m = &((ucontext_t*)(context))->uc_mcontext;

                runtime_printf("v0  %X\n", m->sc_regs[0]);
                runtime_printf("t0  %X\n", m->sc_regs[1]);
                runtime_printf("t1  %X\n", m->sc_regs[2]);
                runtime_printf("t2  %X\n", m->sc_regs[3]);
                runtime_printf("t3  %X\n", m->sc_regs[4]);
                runtime_printf("t4  %X\n", m->sc_regs[5]);
                runtime_printf("t5  %X\n", m->sc_regs[6]);
                runtime_printf("t6  %X\n", m->sc_regs[7]);
                runtime_printf("t7  %X\n", m->sc_regs[8]);
                runtime_printf("s0  %X\n", m->sc_regs[9]);
                runtime_printf("s1  %X\n", m->sc_regs[10]);
                runtime_printf("s2  %X\n", m->sc_regs[11]);
                runtime_printf("s3  %X\n", m->sc_regs[12]);
                runtime_printf("s4  %X\n", m->sc_regs[13]);
                runtime_printf("s5  %X\n", m->sc_regs[14]);
                runtime_printf("fp  %X\n", m->sc_regs[15]);
                runtime_printf("a0  %X\n", m->sc_regs[16]);
                runtime_printf("a1  %X\n", m->sc_regs[17]);
                runtime_printf("a2  %X\n", m->sc_regs[18]);
                runtime_printf("a3  %X\n", m->sc_regs[19]);
                runtime_printf("a4  %X\n", m->sc_regs[20]);
                runtime_printf("a5  %X\n", m->sc_regs[21]);
                runtime_printf("t8  %X\n", m->sc_regs[22]);
                runtime_printf("t9  %X\n", m->sc_regs[23]);
                runtime_printf("t10 %X\n", m->sc_regs[24]);
                runtime_printf("t11 %X\n", m->sc_regs[25]);
                runtime_printf("ra  %X\n", m->sc_regs[26]);
                runtime_printf("t12 %X\n", m->sc_regs[27]);
                runtime_printf("at  %X\n", m->sc_regs[28]);
                runtime_printf("gp  %X\n", m->sc_regs[29]);
                runtime_printf("sp  %X\n", m->sc_regs[30]);
                runtime_printf("pc  %X\n", m->sc_pc);
          }
  #endif
#endif

#if defined(__PPC__) && defined(__LITTLE_ENDIAN__)
  #ifdef __linux__
          {
                mcontext_t *m = &((ucontext_t*)(context))->uc_mcontext;
                int i;

                for (i = 0; i < 32; i++)
                        runtime_printf("r%d %X\n", i, m->regs->gpr[i]);
                runtime_printf("pc  %X\n", m->regs->nip);
                runtime_printf("msr %X\n", m->regs->msr);
                runtime_printf("cr  %X\n", m->regs->ccr);
                runtime_printf("lr  %X\n", m->regs->link);
                runtime_printf("ctr %X\n", m->regs->ctr);
                runtime_printf("xer %X\n", m->regs->xer);
          }
  #endif
#endif

#ifdef __PPC__
  #ifdef _AIX
          {
                mcontext_t *m = &((ucontext_t*)(context))->uc_mcontext;
                int i;

                for (i = 0; i < 32; i++)
                        runtime_printf("r%d %p\n", i, m->jmp_context.gpr[i]);
                runtime_printf("pc  %p\n", m->jmp_context.iar);
                runtime_printf("msr %p\n", m->jmp_context.msr);
                runtime_printf("cr  %x\n", m->jmp_context.cr);
                runtime_printf("lr  %p\n", m->jmp_context.lr);
                runtime_printf("ctr %p\n", m->jmp_context.ctr);
                runtime_printf("xer %x\n", m->jmp_context.xer);
          }
  #endif
#endif
}