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98 lines
2.4 KiB
C
98 lines
2.4 KiB
C
/*
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* Initialise posix-related structures.
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*
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* Copyright (C) 2007-2009 Bahadir Balban
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*/
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#include <l4lib/kip.h>
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#include <l4lib/arch/syslib.h>
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#include <l4lib/arch/utcb.h>
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#include <l4lib/ipcdefs.h>
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#include <l4/macros.h>
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#include INC_GLUE(memlayout.h)
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#include <stdio.h>
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#include <shpage.h>
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#include <sys/types.h>
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#include <sys/shm.h>
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#include <shpage.h>
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#include <libposix.h>
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/*
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* Shared page initialisation of posix-like tasks.
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*
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* POSIX tasks currently use a default shared page for communciation.
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* This could have been also done by long ipc calls.
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*/
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/*
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* Shared page for this task. Used for passing data among ipc
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* parties when message registers are not big enough. Every thread
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* has right to own one, and it has an address unique to every
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* thread. It must be explicitly mapped by both parties of the ipc
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* in order to be useful.
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*/
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void *shared_page;
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/*
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* Obtains a unique address for the task's shared page. Note this
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* just returns the address. This address is used as an shm key
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* to map it via shmget()/shmat() later on.
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*/
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static void *shared_page_address(void)
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{
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void *addr;
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int err;
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/* We're asking it for ourself. */
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write_mr(L4SYS_ARG0, self_tid());
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/* Call pager with utcb address request. Check ipc error. */
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if ((err = l4_sendrecv(PAGER_TID, PAGER_TID,
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L4_IPC_TAG_SHPAGE)) < 0) {
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print_err("%s: L4 IPC Error: %d.\n", __FUNCTION__, err);
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return PTR_ERR(err);
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}
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/* Check if syscall itself was successful */
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if (IS_ERR(addr = (void *)l4_get_retval())) {
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print_err("%s: Request UTCB Address Error: %d.\n",
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__FUNCTION__, (int)addr);
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return addr;
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}
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return addr;
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}
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/*
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* Initialises a non-pager task's default shared memory page
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* using posix semantics. Used during task initialisation
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* and by child tasks after a fork.
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*/
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int shared_page_init(void)
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{
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int shmid;
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void *shmaddr;
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/*
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* Initialise shared page only if we're not the pager.
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* The pager does it differently for itself.
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*/
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BUG_ON(self_tid() == PAGER_TID);
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/* Obtain our shared page address */
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shared_page = shared_page_address();
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//print_err("%s: UTCB Read from mm0 as: 0x%x\n", __FUNCTION__,
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// (unsigned long)shared_page);
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/* Use it as a key to create a shared memory region */
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BUG_ON((shmid = shmget((key_t)shared_page,
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PAGE_SIZE, IPC_CREAT)) < 0);
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/* Attach to the region */
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BUG_ON((shmaddr = shmat(shmid, shared_page, 0)) < 0);
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BUG_ON(shmaddr != shared_page);
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return 0;
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}
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