Commit ef6e06b2 authored by Ira Weiny's avatar Ira Weiny Committed by Andrew Morton
Browse files

highmem: fix kmap_to_page() for kmap_local_page() addresses 

kmap_to_page() is used to get the page for a virtual address which may
be kmap'ed.  Unfortunately, kmap_local_page() stores mappings in a
thread local array separate from kmap().  These mappings were not
checked by the call.

Check the kmap_local_page() mappings and return the page if found.

Because it is intended to remove kmap_to_page() add a warn on once to
the kmap checks to flag potential issues early.

NOTE Due to 32bit x86 use of kmap local in iomap atmoic, KMAP_LOCAL does
not require HIGHMEM to be set.  Therefore the support calls required a
new KMAP_LOCAL section to fix 0day build errors.

[akpm@linux-foundation.org: fix warning]
Link: https://lkml.kernel.org/r/20221006040555.1502679-1-ira.weiny@intel.com


Signed-off-by: default avatarIra Weiny <ira.weiny@intel.com>
Reported-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Reported-by: default avatarkernel test robot <lkp@intel.com>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 15cd9004

mm/highmem.c

+31 −12
Original line number Diff line number Diff line
@@ -30,6 +30,17 @@ 
#include <asm/tlbflush.h>

#include <linux/vmalloc.h>



#ifdef CONFIG_KMAP_LOCAL

static inline int kmap_local_calc_idx(int idx)

{

	return idx + KM_MAX_IDX * smp_processor_id();

}



#ifndef arch_kmap_local_map_idx

#define arch_kmap_local_map_idx(idx, pfn)	kmap_local_calc_idx(idx)

#endif

#endif /* CONFIG_KMAP_LOCAL */



/*

 * Virtual_count is not a pure "count".

 *  0 means that it is not mapped, and has not been mapped
@@ -142,12 +153,29 @@ pte_t *pkmap_page_table; 


struct page *__kmap_to_page(void *vaddr)

{

	unsigned long base = (unsigned long) vaddr & PAGE_MASK;

	struct kmap_ctrl *kctrl = &current->kmap_ctrl;

	unsigned long addr = (unsigned long)vaddr;

	int i;



	/* kmap() mappings */

	if (WARN_ON_ONCE(addr >= PKMAP_ADDR(0) &&

			 addr < PKMAP_ADDR(LAST_PKMAP)))

		return pte_page(pkmap_page_table[PKMAP_NR(addr)]);



	if (addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP)) {

		int i = PKMAP_NR(addr);

	/* kmap_local_page() mappings */

	if (WARN_ON_ONCE(base >= __fix_to_virt(FIX_KMAP_END) &&

			 base < __fix_to_virt(FIX_KMAP_BEGIN))) {

		for (i = 0; i < kctrl->idx; i++) {

			unsigned long base_addr;

			int idx;



		return pte_page(pkmap_page_table[i]);

			idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));

			base_addr = __fix_to_virt(FIX_KMAP_BEGIN + idx);



			if (base_addr == base)

				return pte_page(kctrl->pteval[i]);

		}

	}



	return virt_to_page(vaddr);
@@ -462,10 +490,6 @@ static inline void kmap_local_idx_pop(void) 
# define arch_kmap_local_post_unmap(vaddr)		do { } while (0)

#endif



#ifndef arch_kmap_local_map_idx

#define arch_kmap_local_map_idx(idx, pfn)	kmap_local_calc_idx(idx)

#endif



#ifndef arch_kmap_local_unmap_idx

#define arch_kmap_local_unmap_idx(idx, vaddr)	kmap_local_calc_idx(idx)

#endif
@@ -494,11 +518,6 @@ static inline bool kmap_high_unmap_local(unsigned long vaddr) 
	return false;

}



static inline int kmap_local_calc_idx(int idx)

{

	return idx + KM_MAX_IDX * smp_processor_id();

}



static pte_t *__kmap_pte;



static pte_t *kmap_get_pte(unsigned long vaddr, int idx)