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minix/lib/libsys/vm_procctl.c

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vm: add third-party mmap() mode and PROCCTL these two functions will be used to support all exec() functionality going into a single library shared by RS and VFS and exec() knowledge leaving VM. . third-party mmap: allow certain processes (VFS, RS) to do mmap() on behalf of another process . PROCCTL: used to free and clear a process' address space
2012-06-06 00:50:13 +02:00
#include "syslib.h"
#include <minix/vm.h>
#include <string.h>
/*===========================================================================*
make vfs & filesystems use failable copying 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
2014-01-16 14:22:13 +01:00
* vm_procctl *
vm: add third-party mmap() mode and PROCCTL these two functions will be used to support all exec() functionality going into a single library shared by RS and VFS and exec() knowledge leaving VM. . third-party mmap: allow certain processes (VFS, RS) to do mmap() on behalf of another process . PROCCTL: used to free and clear a process' address space
2012-06-06 00:50:13 +02:00
*===========================================================================*/
make vfs & filesystems use failable copying 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
2014-01-16 14:22:13 +01:00
static int vm_procctl(endpoint_t ep, int param,
vir_bytes m1, vir_bytes len, int flags)
vm: add third-party mmap() mode and PROCCTL these two functions will be used to support all exec() functionality going into a single library shared by RS and VFS and exec() knowledge leaving VM. . third-party mmap: allow certain processes (VFS, RS) to do mmap() on behalf of another process . PROCCTL: used to free and clear a process' address space
2012-06-06 00:50:13 +02:00
{
message m;
int result;
memset(&m, 0, sizeof(m));
m.VMPCTL_WHO = ep;
m.VMPCTL_PARAM = param;
make vfs & filesystems use failable copying 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
2014-01-16 14:22:13 +01:00
m.VMPCTL_M1 = m1;
m.VMPCTL_LEN = len;
m.VMPCTL_FLAGS = flags;
vm: add third-party mmap() mode and PROCCTL these two functions will be used to support all exec() functionality going into a single library shared by RS and VFS and exec() knowledge leaving VM. . third-party mmap: allow certain processes (VFS, RS) to do mmap() on behalf of another process . PROCCTL: used to free and clear a process' address space
2012-06-06 00:50:13 +02:00
result = _taskcall(VM_PROC_NR, VM_PROCCTL, &m);
return(result);
}
exec() cleanup, generalization, improvement . make exec() callers (i.e. vfs and rs) determine the memory layout by explicitly reserving regions using mmap() calls on behalf of the exec()ing process, i.e. handling all of the exec logic, thereby eliminating all special exec() knowledge from VM. . the new procedure is: clear the exec()ing process first, then call third-party mmap()s to reserve memory, then copy the executable file section contents in, all using callbacks tailored to the caller's way of starting an executable . i.e. no more explicit EXEC_NEWMEM-style calls in PM or VM as with rigid 2-section arguments . this naturally allows generalizing exec() by simply loading all ELF sections . drop/merge of lots of duplicate exec() code into libexec . not copying the code sections to vfs and into the executable again is a measurable performance improvement (about 3.3% faster for 'make' in src/servers/)
2012-05-30 19:34:07 +02:00
make vfs & filesystems use failable copying 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
2014-01-16 14:22:13 +01:00
int vm_procctl_clear(endpoint_t ep)
{
return vm_procctl(ep, VMPPARAM_CLEAR, 0, 0, 0);
}
int vm_procctl_handlemem(endpoint_t ep, vir_bytes m1, vir_bytes len,
int writeflag)
{
return vm_procctl(ep, VMPPARAM_HANDLEMEM, m1, len, writeflag);
}
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