diff options
| -rw-r--r-- | hurd/hurdsig.c | 18 | ||||
| -rw-r--r-- | sysdeps/mach/hurd/i386/intr-msg.h | 40 | ||||
| -rw-r--r-- | sysdeps/mach/hurd/i386/trampoline.c | 21 |
3 files changed, 31 insertions, 48 deletions
diff --git a/hurd/hurdsig.c b/hurd/hurdsig.c index ea79ffb597..5ff0a91fea 100644 --- a/hurd/hurdsig.c +++ b/hurd/hurdsig.c @@ -415,6 +415,7 @@ _hurdsig_abort_rpcs (struct hurd_sigstate *ss, int signo, int sigthread, void (*reply) (void)) { extern const void _hurd_intr_rpc_msg_about_to; + extern const void _hurd_intr_rpc_msg_setup_done; extern const void _hurd_intr_rpc_msg_in_trap; mach_port_t rcv_port = MACH_PORT_NULL; mach_port_t intr_port; @@ -434,11 +435,18 @@ _hurdsig_abort_rpcs (struct hurd_sigstate *ss, int signo, int sigthread, && state->basic.PC < (uintptr_t) &_hurd_intr_rpc_msg_in_trap) { /* The thread is about to do the RPC, but hasn't yet entered - mach_msg. Mutate the thread's state so it knows not to try - the RPC. */ - INTR_MSG_BACK_OUT (&state->basic); - MACHINE_THREAD_STATE_SET_PC (&state->basic, - &_hurd_intr_rpc_msg_in_trap); + mach_msg. Importantly, it may have already checked ss->cancel for + the last time before doing the RPC, so setting that is not enough + to make it not enter mach_msg. Instead, mutate the thread's state + so it knows not to try the RPC. + + If the thread is past _hurd_intr_rpc_msg_setup_done, just make it + jump to after the trap, since we know it's safe to do so. Otherwise, + we know that the thread is yet to check for the MACH_SEND_INTERRUPTED + value we set below, and will skip the trap by itself. */ + if (state->basic.PC >= (uintptr_t) &_hurd_intr_rpc_msg_setup_done) + MACHINE_THREAD_STATE_SET_PC (&state->basic, + &_hurd_intr_rpc_msg_in_trap); state->basic.SYSRETURN = MACH_SEND_INTERRUPTED; *state_change = 1; } diff --git a/sysdeps/mach/hurd/i386/intr-msg.h b/sysdeps/mach/hurd/i386/intr-msg.h index 29cb4620da..21088fa8c4 100644 --- a/sysdeps/mach/hurd/i386/intr-msg.h +++ b/sysdeps/mach/hurd/i386/intr-msg.h @@ -25,10 +25,13 @@ ({ \ error_t err; \ asm (".globl _hurd_intr_rpc_msg_about_to\n" \ - ".globl _hurd_intr_rpc_msg_cx_sp\n" \ - ".globl _hurd_intr_rpc_msg_do_trap\n" \ + ".globl _hurd_intr_rpc_msg_setup_done\n" \ ".globl _hurd_intr_rpc_msg_in_trap\n" \ - ".globl _hurd_intr_rpc_msg_sp_restored\n" \ + /* Clear eax before we do the check for cancel below. This is to + detect eax being set to non-zero (actually MACH_SEND_INTERRUPTED) + from the outside (namely, _hurdsig_abort_rpcs), which signals us + to skip the trap we were about to enter. */ \ + " xorl %0, %0\n" \ "_hurd_intr_rpc_msg_about_to:" \ /* We need to make a last check of cancel, in case we got interrupted right before _hurd_intr_rpc_msg_about_to. */ \ @@ -36,10 +39,10 @@ " jz _hurd_intr_rpc_msg_do\n" \ /* We got interrupted, note so and return EINTR. */ \ " movl $0, %3\n" \ - " movl %6, %%eax\n" \ + " movl %6, %0\n" \ " jmp _hurd_intr_rpc_msg_sp_restored\n" \ "_hurd_intr_rpc_msg_do:" \ - /* Ok, push the mach_msg_trap arguments. */ \ + /* Ok, push the mach_msg_trap arguments and a fake return address. */ \ " pushl 24(%4)\n" \ " pushl %2\n" \ " pushl 16(%4)\n" \ @@ -48,9 +51,14 @@ " pushl %1\n" \ " pushl (%4)\n" \ " pushl $0\n" \ - /* TODO: remove this ecx kludge, we don't need it any more */ \ - " movl %%esp, %%ecx\n" \ - "_hurd_intr_rpc_msg_cx_sp: movl $-25, %%eax\n" \ + "_hurd_intr_rpc_msg_setup_done:" \ + /* From here on, it is safe to make us jump over the syscall. Now + check if we have been told to skip the syscall while running + the above. */ \ + " test %0, %0\n" \ + " jnz _hurd_intr_rpc_msg_in_trap\n" \ + /* Do the actual syscall. */ \ + " movl $-25, %%eax\n" \ "_hurd_intr_rpc_msg_do_trap: lcall $7, $0 # status in %0\n" \ "_hurd_intr_rpc_msg_in_trap:" \ /* Ok, clean the arguments and update OPTION and TIMEOUT. */ \ @@ -60,22 +68,10 @@ " popl %2\n" \ " addl $4, %%esp\n" \ "_hurd_intr_rpc_msg_sp_restored:" \ - : "=a" (err), "+r" (option), "+r" (timeout), "=m" (*intr_port_p) \ - : "r" (&msg), "m" (*cancel_p), "i" (EINTR) \ - : "ecx"); \ + : "=&a" (err), "+r" (option), "+r" (timeout), "=m" (*intr_port_p) \ + : "r" (&msg), "m" (*cancel_p), "i" (EINTR)); \ err; \ }) - - -static void inline -INTR_MSG_BACK_OUT (struct i386_thread_state *state) -{ - extern const void _hurd_intr_rpc_msg_cx_sp; - if (state->eip >= (natural_t) &_hurd_intr_rpc_msg_cx_sp) - state->uesp = state->ecx; - else - state->ecx = state->uesp; -} #include "hurdfault.h" diff --git a/sysdeps/mach/hurd/i386/trampoline.c b/sysdeps/mach/hurd/i386/trampoline.c index 42c9d73207..8f481e79b8 100644 --- a/sysdeps/mach/hurd/i386/trampoline.c +++ b/sysdeps/mach/hurd/i386/trampoline.c @@ -89,8 +89,6 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, const struct sigaction *action void trampoline (void); void rpc_wait_trampoline (void); void firewall (void); - extern const void _hurd_intr_rpc_msg_cx_sp; - extern const void _hurd_intr_rpc_msg_sp_restored; void *volatile sigsp; struct sigcontext *scp; struct @@ -146,25 +144,6 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, const struct sigaction *action interrupted RPC frame. */ state->basic.esp = state->basic.uesp; - /* This code has intimate knowledge of the special mach_msg system call - done in intr-msg.c; that code does (see intr-msg.h): - movl %esp, %ecx - leal ARGS, %esp - _hurd_intr_rpc_msg_cx_sp: movl $-25, %eax - _hurd_intr_rpc_msg_do_trap: lcall $7, $0 - _hurd_intr_rpc_msg_in_trap: movl %ecx, %esp - _hurd_intr_rpc_msg_sp_restored: - We must check for the window during which %esp points at the - mach_msg arguments. The space below until %ecx is used by - the _hurd_intr_rpc_mach_msg frame, and must not be clobbered. */ - if (state->basic.eip >= (int) &_hurd_intr_rpc_msg_cx_sp - && state->basic.eip < (int) &_hurd_intr_rpc_msg_sp_restored) - /* The SP now points at the mach_msg args, but there is more stack - space used below it. The real SP is saved in %ecx; we must push the - new frame below there (if not on the altstack), and restore that value as - the SP on sigreturn. */ - state->basic.uesp = state->basic.ecx; - if ((action->sa_flags & SA_ONSTACK) && !(ss->sigaltstack.ss_flags & (SS_DISABLE|SS_ONSTACK))) { |