Jamie LiuandgVisor bot 86ceb5c26a Fix memmap.Translation.Perms returns. ...

memmap.Mappable.Translate() is passed a hostarch.AccessType indicating what
permissions are *immediately* required; it returns permissions in
memmap.Translation.Perms that are granted *to MM* until invalidation. MM
ensures that the permissions granted to the application are the intersection of
those granted by Translate, and those granted by VMA permissions; see
determination of pma.effectivePerms in
mm.MemoryManager.getPMAsInternalLocked(). This mechanism is used to avoid
marking pages dirty in the sentry's page cache for gofer-backed files until
PROT_WRITE pages are actually written to; see gofer.dentry.Translate(). In most
other cases, granting all supported permissions (to MM) up-front avoids a
redundant page fault for pages that are touched first for reading, and later
for writing.

Also:

- Prevent PROT_WRITE mappings of erofs files at mmap()/mprotect() time, rather
  than raising SIGBUS when writing to such mappings.

- Map nvproxy.frontendFD with PlatformEffectPopulate. This is the original goal
  of this CL; however, before this rest of this CL, MM.MMap() =>
  MM.populateVMAAndUnlock() => MM.getPMAsLocked(at=hostarch.NoAccess) =>
  MM.getPMAsInternalLocked(at=hostarch.NoAccess) =>
  nvproxy.frontendFD.Translate(at=hostarch.NoAccess) returns Translations with
  no permissions, causing MM.mapASLocked() to no-op.

PiperOrigin-RevId: 679360594

2024-09-26 17:59:37 -07:00

..

buffer.go

Fix a few typos

2023-10-25 12:13:42 -07:00

BUILD

Add default_applicable_licenses rules to packages.

2023-03-02 10:50:04 -08:00

iouringfs_state.go

Delete pgalloc.MemoryFileProvider.

2024-03-12 20:06:58 -07:00

iouringfs_test.go

io_uring: Fix several issues with shared ring buffers.

2022-11-17 12:45:32 -08:00

iouringfs_unsafe.go

Avoid use of gohacks.SliceHeader to access pointer to data

2023-01-24 16:42:27 -08:00

iouringfs.go

Fix memmap.Translation.Perms returns.

2024-09-26 17:59:37 -07:00