565f13088f
Change the kernel to add features to vircopy and safecopies so that
transparent copy fixing won't happen to avoid deadlocks, and such copies
fail with EFAULT.
Transparently making copying work from filesystems (as normally done by
the kernel & VM when copying fails because of missing/readonly memory)
is problematic as it can happen that, for file-mapped ranges, that that
same filesystem that is blocked on the copy request is needed to satisfy
the memory range, leading to deadlock. Dito for VFS itself, if done with
a blocking call.
This change makes the copying done from a filesystem fail in such cases
with EFAULT by VFS adding the CPF_TRY flag to the grants. If a FS call
fails with EFAULT, VFS will then request the range to be made available
to VM after the FS is unblocked, allowing it to be used to satisfy the
range if need be in another VFS thread.
Similarly, for datacopies that VFS itself does, it uses the failable
vircopy variant and callers use a wrapper that talk to VM if necessary
to get the copy to work.
. kernel: add CPF_TRY flag to safecopies
. kernel: only request writable ranges to VM for the
target buffer when copying fails
. do copying in VFS TRY-first
. some fixes in VM to build SANITYCHECK mode
. add regression test for the cases where
- a FS system call needs memory mapped in a process that the
FS itself must map.
- such a range covers more than one file-mapped region.
. add 'try' mode to vircopy, physcopy
. add flags field to copy kernel call messages
. if CP_FLAG_TRY is set, do not transparently try
to fix memory ranges
. for use by VFS when accessing user buffers to avoid
deadlock
. remove some obsolete backwards compatability assignments
. VFS: let thread scheduling work for VM requests too
Allows VFS to make calls to VM while suspending and resuming
the currently running thread. Does currently not work for the
main thread.
. VM: add fix memory range call for use by VFS
Change-Id: I295794269cea51a3163519a9cfe5901301d90b32
122 lines
3.5 KiB
C
122 lines
3.5 KiB
C
/* The kernel call implemented in this file:
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* m_type: SYS_UMAP_REMOTE
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*
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* The parameters for this kernel call are:
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* m5_i1: CP_SRC_PROC_NR (process number)
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* m5_s1: UMAP_SEG (segment where address is: T, D, or S)
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* m5_l1: CP_SRC_ADDR (virtual address)
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* m5_i2: CP_DST_ENDPT (process number of grantee to check access for)
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* m5_l2: CP_DST_ADDR (returns physical address)
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* m5_l3: CP_NR_BYTES (size of datastructure)
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*/
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#include "kernel/system.h"
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#include <minix/endpoint.h>
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#if USE_UMAP || USE_UMAP_REMOTE
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#if ! USE_UMAP_REMOTE
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#undef do_umap_remote
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#endif
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/*==========================================================================*
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* do_umap_remote *
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*==========================================================================*/
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int do_umap_remote(struct proc * caller, message * m_ptr)
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{
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/* Map virtual address to physical, for non-kernel processes. */
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int seg_type = m_ptr->UMAP_SEG & SEGMENT_TYPE;
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int seg_index = m_ptr->UMAP_SEG & SEGMENT_INDEX;
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vir_bytes offset = m_ptr->CP_SRC_ADDR;
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int count = m_ptr->CP_NR_BYTES;
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int endpt = (int) m_ptr->CP_SRC_ENDPT;
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endpoint_t grantee = (endpoint_t) m_ptr->CP_DST_ENDPT;
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int proc_nr, proc_nr_grantee;
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phys_bytes phys_addr = 0, lin_addr = 0;
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struct proc *targetpr;
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/* Verify process number. */
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if (endpt == SELF)
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okendpt(caller->p_endpoint, &proc_nr);
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else
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if (! isokendpt(endpt, &proc_nr))
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return(EINVAL);
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targetpr = proc_addr(proc_nr);
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/* Verify grantee endpoint */
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if (grantee == SELF) {
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grantee = caller->p_endpoint;
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} else if (grantee == NONE ||
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grantee == ANY ||
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seg_index != MEM_GRANT ||
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!isokendpt(grantee, &proc_nr_grantee)) {
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return EINVAL;
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}
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/* See which mapping should be made. */
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switch(seg_type) {
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case LOCAL_VM_SEG:
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if(seg_index == MEM_GRANT) {
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vir_bytes newoffset;
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endpoint_t newep;
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int new_proc_nr;
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cp_grant_id_t grant = (cp_grant_id_t) offset;
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if(verify_grant(targetpr->p_endpoint, grantee, grant, count,
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0, 0, &newoffset, &newep, NULL) != OK) {
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printf("SYSTEM: do_umap: verify_grant in %s, grant %d, bytes 0x%lx, failed, caller %s\n", targetpr->p_name, offset, count, caller->p_name);
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proc_stacktrace(caller);
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return EFAULT;
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}
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if(!isokendpt(newep, &new_proc_nr)) {
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printf("SYSTEM: do_umap: isokendpt failed\n");
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return EFAULT;
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}
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/* New lookup. */
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offset = newoffset;
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targetpr = proc_addr(new_proc_nr);
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seg_index = VIR_ADDR;
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}
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if(seg_index == VIR_ADDR) {
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phys_addr = lin_addr = offset;
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} else {
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printf("SYSTEM: bogus seg type 0x%lx\n", seg_index);
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return EFAULT;
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}
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if(!lin_addr) {
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printf("SYSTEM:do_umap: umap_local failed\n");
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return EFAULT;
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}
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if(vm_lookup(targetpr, lin_addr, &phys_addr, NULL) != OK) {
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printf("SYSTEM:do_umap: vm_lookup failed\n");
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return EFAULT;
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}
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if(phys_addr == 0)
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panic("vm_lookup returned zero physical address");
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break;
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default:
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printf("umap: peculiar type\n");
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return EINVAL;
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}
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if(vm_running && vm_lookup_range(targetpr, lin_addr, NULL, count) != count) {
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printf("SYSTEM:do_umap: not contiguous\n");
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return EFAULT;
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}
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m_ptr->CP_DST_ADDR = phys_addr;
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if(phys_addr == 0) {
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printf("kernel: umap 0x%x done by %d / %s, pc 0x%lx, 0x%lx -> 0x%lx\n",
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seg_type, caller->p_endpoint, caller->p_name,
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caller->p_reg.pc, offset, phys_addr);
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printf("caller stack: ");
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proc_stacktrace(caller);
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}
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return (phys_addr == 0) ? EFAULT: OK;
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}
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#endif /* USE_UMAP || USE_UMAP_REMOTE */
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