STRLCPY/criu

mem: Don't do unneeded mprotects

When a vma we restore doesn't have any pages in pagemaps there's
not need to enforce PROT_WRITE bit on it.

This only applies to non-premmaped vmas.

Signed-off-by: Pavel Emelyanov <[email protected]>
Signed-off-by: Andrei Vagin <[email protected]>

Pavel Emelyanov committed 7 years ago

c9194500

1 parent 91388fce

Total 3 files Show one by one

■ ■ ■ ■ ■ ■

criu/include/image.h

		skipped 88 lines
89	89		#define VMA_AREA_VVAR (1 << 12)
90	90		#define VMA_AREA_AIORING (1 << 13)
91	91
	92	+	#define VMA_NO_PROT_WRITE (1 << 29)
92	93		#define VMA_PREMMAPED (1 << 30)
93	94		#define VMA_UNSUPP (1 << 31)
94	95
		skipped 77 lines

■ ■ ■ ■ ■ ■ ■

criu/mem.c

		skipped 658 lines
659	659		}
660	660		}
661	661
	662	+	/*
	663	+	* All mappings here get PROT_WRITE regardless of whether we
	664	+	* put any data into it or not, because this area will get
	665	+	* mremap()-ed (branch below) so we MIGHT need to have WRITE
	666	+	* bits there. Ideally we'd check for the whole COW-chain
	667	+	* having any data in.
	668	+	*/
662	669		addr = mmap(*tgt_addr, size,
663	670		vma->e->prot \| PROT_WRITE,
664	671		vma->e->flags \| MAP_FIXED \| flag,
		skipped 90 lines
755	762		if (!vma_area_is_private(vma, kdat.task_size))
756	763		continue;
757	764
758		-	if (vma->pvma == NULL && pr->pieok && !vma_force_premap(vma, &vmas->h))
	765	+	if (vma->pvma == NULL && pr->pieok && !vma_force_premap(vma, &vmas->h)) {
759	766		/*
760	767		* VMA in question is not shared with anyone. We'll
761	768		* restore it with its contents in restorer.
	769	+	* Now let's check whether we need to map it with
	770	+	* PROT_WRITE or not.
762	771		*/
	772	+	do {
	773	+	if (pr->pe->vaddr + pr->pe->nr_pages * PAGE_SIZE <= vma->e->start)
	774	+	continue;
	775	+	if (pr->pe->vaddr > vma->e->end)
	776	+	vma->e->status \|= VMA_NO_PROT_WRITE;
	777	+	break;
	778	+	} while (pr->advance(pr));
	779	+
763	780		continue;
	781	+	}
764	782
765	783		ret = premap_private_vma(t, vma, at);
	784	+
766	785		if (ret < 0)
767	786		break;
768	787		}
		skipped 61 lines
830	849		unsigned long len = min_t(unsigned long,
831	850		(nr_pages - i) * PAGE_SIZE,
832	851		vma->e->end - va);
	852	+
	853	+	if (vma->e->status & VMA_NO_PROT_WRITE) {
	854	+	pr_debug("VMA 0x%"PRIx64":0x%"PRIx64" RO %#lx:%lu IO\n",
	855	+	vma->e->start, vma->e->end, va, nr_pages);
	856	+	BUG();
	857	+	}
833	858
834	859		if (pagemap_enqueue_iovec(pr, (void *)va, len, vma_io))
835	860		return -1;
		skipped 277 lines

■ ■ ■ ■ ■ ■

criu/pie/restorer.c

		skipped 599 lines
600	600		flags \|= MAP_ANONYMOUS;
601	601
602	602		/* A mapping of file with MAP_SHARED is up to date */
603		-	if (vma_entry->fd == -1 \|\| !(vma_entry->flags & MAP_SHARED))
	603	+	if ((vma_entry->fd == -1 \|\| !(vma_entry->flags & MAP_SHARED)) &&
	604	+	!(vma_entry->status & VMA_NO_PROT_WRITE))
604	605		prot \|= PROT_WRITE;
605	606
606	607		pr_debug("\tmmap(%"PRIx64" -> %"PRIx64", %x %x %d)\n",
		skipped 654 lines
1261	1262		if (!(vma_entry_is(vma_entry, VMA_AREA_REGULAR)))
1262	1263		continue;
1263	1264
1264		-	if (vma_entry->prot & PROT_WRITE)
	1265	+	if ((vma_entry->prot & PROT_WRITE) \|\|
	1266	+	(vma_entry->status & VMA_NO_PROT_WRITE))
1265	1267		continue;
1266	1268
1267	1269		sys_mprotect(decode_pointer(vma_entry->start),
		skipped 324 lines