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authorSamuel Thibault <samuel.thibault@ens-lyon.org>2018-10-09 23:40:09 +0200
committerSamuel Thibault <samuel.thibault@ens-lyon.org>2018-10-28 13:41:51 +0100
commit5c81be53407434ce22b849722a3d691295480016 (patch)
tree930f36f9263b5d02c176d6b13b0ed5a762c8fd83 /sysdeps/mach/hurd/i386/intr-msg.h
parent2d0d1d38761cd9aeb7063c5cce1993cec909f67f (diff)
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hurd: Fix race between calling RPC and handling a signal
	* sysdeps/mach/hurd/i386/intr-msg.h (INTR_MSG_TRAP): Make
	_hurd_intr_rpc_msg_about_to global point to start of controlled
	assembly snippet. Make it check canceled flag.
	* hurd/hurdsig.c (_hurdsig_abort_rpcs): Only mutate thread if it passed
	the _hurd_intr_rpc_msg_about_to point.
	* hurd/intr-msg.c (_hurd_intr_rpc_mach_msg): Remove comment on mutation
	issue, remove cancel flag check.
Diffstat (limited to 'sysdeps/mach/hurd/i386/intr-msg.h')
-rw-r--r--sysdeps/mach/hurd/i386/intr-msg.h23
1 files changed, 16 insertions, 7 deletions
diff --git a/sysdeps/mach/hurd/i386/intr-msg.h b/sysdeps/mach/hurd/i386/intr-msg.h
index 64f05f8c4e..7788c3b892 100644
--- a/sysdeps/mach/hurd/i386/intr-msg.h
+++ b/sysdeps/mach/hurd/i386/intr-msg.h
@@ -20,21 +20,30 @@
 /* Note that we must mark OPTION and TIMEOUT as outputs of this operation,
    to indicate that the signal thread might mutate them as part
    of sending us to a signal handler.  */
-#define INTR_MSG_TRAP(msg, option, send_size, rcv_size, rcv_name, timeout, notify) \
+
+/* After _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.  */
+#define INTR_MSG_TRAP(msg, option, send_size, rcv_size, rcv_name, timeout, notify, cancel_p, intr_port_p) \
 ({									      \
   error_t err;								      \
-  asm (".globl _hurd_intr_rpc_msg_do_trap\n" 				      \
-       ".globl _hurd_intr_rpc_msg_in_trap\n"				      \
+  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_in_trap\n"				      \
        ".globl _hurd_intr_rpc_msg_sp_restored\n"			      \
-       "				movl %%esp, %%ecx\n"		      \
-       "				leal %3, %%esp\n"		      \
+       "_hurd_intr_rpc_msg_about_to:	cmpl $0, %5\n"			      \
+       "				jz _hurd_intr_rpc_msg_do\n"	      \
+       "				movl $0, %3\n"			      \
+       "				movl %6, %%eax\n"		      \
+       "				jmp _hurd_intr_rpc_msg_sp_restored\n" \
+       "_hurd_intr_rpc_msg_do:		movl %%esp, %%ecx\n"		      \
+       "				leal %4, %%esp\n"		      \
        "_hurd_intr_rpc_msg_cx_sp:	movl $-25, %%eax\n"		      \
        "_hurd_intr_rpc_msg_do_trap:	lcall $7, $0 # status in %0\n"	      \
        "_hurd_intr_rpc_msg_in_trap:	movl %%ecx, %%esp\n"		      \
        "_hurd_intr_rpc_msg_sp_restored:"				      \
-       : "=a" (err), "+m" (option), "+m" (timeout)			      \
-       : "m" ((&msg)[-1])						      \
+       : "=a" (err), "+m" (option), "+m" (timeout), "=m" (*intr_port_p)	      \
+       : "m" ((&msg)[-1]), "m" (*cancel_p), "i" (EINTR)			      \
        : "ecx");							      \
   err;									      \
 })