parisc: Ensure full cache coherency for kmap/kunmap

Helge Deller noted a few weeks ago problems with the AIO support on parisc. This change is the result of numerous iterations on how best to deal with this problem. The solution adopted here is to provide full cache coherency in a uniform manner on all parisc systems. This involves calling flush_dcache_page() on kmap operations and flush_kernel_dcache_page() on kunmap operations. As a result, the copy_user_page() and clear_user_page() functions can be removed and the overall code is simpler. The change ensures that both userspace and kernel aliases to a mapped page are invalidated and flushed. This is necessary for the correct operation of PA8800 and PA8900 based systems which do not support inequivalent aliases. With this change, I have observed no cache related issues on c8000 and rp3440. It is now possible for example to do kernel builds with "-j64" on four way systems. On systems using XFS file systems, the patch recently posted by Mikulas Patocka to "fix crash using XFS on loopback" is needed to avoid a hang caused by an uninitialized lock passed to flush_dcache_page() in the page struct.

John David Anglin committed 12 years ago

Commit f8dae001 parent ceb3b023 files · +6 −46Browse files

Unified · Split

3 files

arch/parisc/include/asm/cacheflush.h +4 −8
arch/parisc/include/asm/page.h +2 −3
arch/parisc/kernel/cache.c +0 −35

arch/parisc/include/asm/cacheflush.h+4−8

@@ -125,42 +125,38 @@ flush_anon_page(struct vm_area_struct vma, struct page page, unsigned long vma · 124 unmodified lines
125	125	void mark_rodata_ro(void);
126	126	#endif
127	127
128		−#ifdef CONFIG_PA8X00
129		−/* Only pa8800, pa8900 needs this */
130		−
131	128	#include <asm/kmap_types.h>
132	129
133	130	#define ARCH_HAS_KMAP
134	131
135		−void kunmap_parisc(void *addr);
136		−
137	132	static inline void kmap(struct page page)
138	133	{
139	134	might_sleep();
	135	+ flush_dcache_page(page);
140	136	return page_address(page);
141	137	}
142	138
143	139	static inline void kunmap(struct page *page)
144	140	{
145		− kunmap_parisc(page_address(page));
	141	+ flush_kernel_dcache_page_addr(page_address(page));
146	142	}
147	143
148	144	static inline void kmap_atomic(struct page page)
149	145	{
150	146	pagefault_disable();
	147	+ flush_dcache_page(page);
151	148	return page_address(page);
152	149	}
153	150
154	151	static inline void __kunmap_atomic(void *addr)
155	152	{
156		− kunmap_parisc(addr);
	153	+ flush_kernel_dcache_page_addr(addr);
157	154	pagefault_enable();
158	155	}
159	156
160	157	#define kmap_atomic_prot(page, prot) kmap_atomic(page)
161	158	#define kmap_atomic_pfn(pfn) kmap_atomic(pfn_to_page(pfn))
162	159	#define kmap_atomic_to_page(ptr) virt_to_page(ptr)
163		−#endif
164	160
165	161	#endif /* _PARISC_CACHEFLUSH_H */
166	162

arch/parisc/include/asm/page.h+2−3

@@ -28,9 +28,8 @@ struct page; · 27 unmodified lines
28	28
29	29	void clear_page_asm(void *page);
30	30	void copy_page_asm(void to, void from);
31		−void clear_user_page(void vto, unsigned long vaddr, struct page pg);
32		−void copy_user_page(void vto, void vfrom, unsigned long vaddr,
33		− struct page *pg);
	31	+#define clear_user_page(vto, vaddr, page) clear_page_asm(vto)
	32	+#define copy_user_page(vto, vfrom, vaddr, page) copy_page_asm(vto, vfrom)
34	33
35	34	/* #define CONFIG_PARISC_TMPALIAS */
36	35

arch/parisc/kernel/cache.c+0−35

@@ -388,41 +388,6 @@ void flush_kernel_dcache_page_addr(void *addr) · 387 unmodified lines
388	388	}
389	389	EXPORT_SYMBOL(flush_kernel_dcache_page_addr);
390	390
391		−void clear_user_page(void vto, unsigned long vaddr, struct page page)
392		−{
393		− clear_page_asm(vto);
394		− if (!parisc_requires_coherency())
395		− flush_kernel_dcache_page_asm(vto);
396		−}
397		−EXPORT_SYMBOL(clear_user_page);
398		−
399		−void copy_user_page(void vto, void vfrom, unsigned long vaddr,
400		− struct page *pg)
401		−{
402		− /* Copy using kernel mapping. No coherency is needed
403		− (all in kmap/kunmap) on machines that don't support
404		− non-equivalent aliasing. However, the `from' page
405		− needs to be flushed before it can be accessed through
406		− the kernel mapping. */
407		− preempt_disable();
408		− flush_dcache_page_asm(__pa(vfrom), vaddr);
409		− preempt_enable();
410		− copy_page_asm(vto, vfrom);
411		− if (!parisc_requires_coherency())
412		− flush_kernel_dcache_page_asm(vto);
413		−}
414		−EXPORT_SYMBOL(copy_user_page);
415		−
416		−#ifdef CONFIG_PA8X00
417		−
418		−void kunmap_parisc(void *addr)
419		−{
420		− if (parisc_requires_coherency())
421		− flush_kernel_dcache_page_addr(addr);
422		−}
423		−EXPORT_SYMBOL(kunmap_parisc);
424		−#endif
425		−
426	391	void purge_tlb_entries(struct mm_struct *mm, unsigned long addr)
427	392	{
428	393	unsigned long flags;