Commit 949e51be authored by David Daney's avatar David Daney Committed by Ralf Baechle
Browse files

MIPS: Make TASK_SIZE reflect proper size for both 32 and 64 bit processes. 



The TASK_SIZE macro should reflect the size of a user process virtual
address space.  Previously for 64-bit kernels, this was not the case.
The immediate cause of pain was in
hugetlbfs/inode.c:hugetlb_get_unmapped_area() where 32-bit processes
trying to mmap a huge page would be served a page with an address
outside of the 32-bit address range.  But there are other uses of
TASK_SIZE in the kernel as well that would like an accurate value.

The new definition is nice because it now makes TASK_SIZE and
TASK_SIZE_OF() yield the same value for any given process.

For 32-bit kernels there should be no change, although I did factor
out some code in asm/processor.h that became identical for the 32-bit and
64-bit cases.

__UA_LIMIT is now set to ~((1 << SEGBITS) - 1) for 64-bit kernels.
This should eliminate the possibility of getting a
AddressErrorException in the kernel for addresses that pass the
access_ok() test.

With the patch applied, I can still run o32, n32 and n64 processes,
and have an o32 shell fork/exec both n32 and n64 processes.

Signed-off-by: default avatarDavid Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1701/
parent 18d693b3

arch/mips/include/asm/pgtable-64.h

+2 −2
Original line number Diff line number Diff line
@@ -113,10 +113,10 @@ 
#endif

#define PTRS_PER_PTE	((PAGE_SIZE << PTE_ORDER) / sizeof(pte_t))



#if PGDIR_SIZE >= TASK_SIZE

#if PGDIR_SIZE >= TASK_SIZE64

#define USER_PTRS_PER_PGD       (1)

#else

#define USER_PTRS_PER_PGD	(TASK_SIZE / PGDIR_SIZE)

#define USER_PTRS_PER_PGD	(TASK_SIZE64 / PGDIR_SIZE)

#endif

#define FIRST_USER_ADDRESS	0UL

arch/mips/include/asm/processor.h

+19 −21
Original line number Diff line number Diff line
@@ -50,13 +50,10 @@ extern unsigned int vced_count, vcei_count; 
 * so don't change it unless you know what you are doing.

 */

#define TASK_SIZE	0x7fff8000UL

#define STACK_TOP	((TASK_SIZE & PAGE_MASK) - SPECIAL_PAGES_SIZE)



/*

 * This decides where the kernel will search for a free chunk of vm

 * space during mmap's.

 */

#define TASK_UNMAPPED_BASE	((TASK_SIZE / 3) & ~(PAGE_SIZE))

#ifdef __KERNEL__

#define STACK_TOP_MAX	TASK_SIZE

#endif



#define TASK_IS_32BIT_ADDR 1
@@ -71,28 +68,29 @@ extern unsigned int vced_count, vcei_count; 
 * 8192EB ...

 */

#define TASK_SIZE32	0x7fff8000UL

#define TASK_SIZE	0x10000000000UL

#define STACK_TOP	\

	(((test_thread_flag(TIF_32BIT_ADDR) ?				\

	   TASK_SIZE32 : TASK_SIZE) & PAGE_MASK) - SPECIAL_PAGES_SIZE)

#define TASK_SIZE64	0x10000000000UL

#define TASK_SIZE (test_thread_flag(TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE64)



#ifdef __KERNEL__

#define STACK_TOP_MAX	TASK_SIZE64

#endif





/*

 * This decides where the kernel will search for a free chunk of vm

 * space during mmap's.

 */

#define TASK_UNMAPPED_BASE						\

	(test_thread_flag(TIF_32BIT_ADDR) ?				\

		PAGE_ALIGN(TASK_SIZE32 / 3) : PAGE_ALIGN(TASK_SIZE / 3))

#define TASK_SIZE_OF(tsk)						\

	(test_tsk_thread_flag(tsk, TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE)

	(test_tsk_thread_flag(tsk, TIF_32BIT_ADDR) ? TASK_SIZE32 : TASK_SIZE64)



#define TASK_IS_32BIT_ADDR test_thread_flag(TIF_32BIT_ADDR)



#endif



#ifdef __KERNEL__

#define STACK_TOP_MAX	TASK_SIZE

#endif

#define STACK_TOP	((TASK_SIZE & PAGE_MASK) - SPECIAL_PAGES_SIZE)



/*

 * This decides where the kernel will search for a free chunk of vm

 * space during mmap's.

 */

#define TASK_UNMAPPED_BASE PAGE_ALIGN(TASK_SIZE / 3)





#define NUM_FPU_REGS	32

arch/mips/include/asm/uaccess.h

+3 −1
Original line number Diff line number Diff line
@@ -35,7 +35,9 @@ 


#ifdef CONFIG_64BIT



#define __UA_LIMIT	(- TASK_SIZE)

extern u64 __ua_limit;



#define __UA_LIMIT	__ua_limit



#define __UA_ADDR	".dword"

#define __UA_LA		"dla"

arch/mips/kernel/cpu-probe.c

+13 −0
Original line number Diff line number Diff line
@@ -25,6 +25,8 @@ 
#include <asm/system.h>

#include <asm/watch.h>

#include <asm/spram.h>

#include <asm/uaccess.h>



/*

 * Not all of the MIPS CPUs have the "wait" instruction available. Moreover,

 * the implementation of the "wait" feature differs between CPU families. This
@@ -987,6 +989,12 @@ static inline void cpu_probe_ingenic(struct cpuinfo_mips *c, unsigned int cpu) 
	}

}



#ifdef CONFIG_64BIT

/* For use by uaccess.h */

u64 __ua_limit;

EXPORT_SYMBOL(__ua_limit);

#endif



const char *__cpu_name[NR_CPUS];

const char *__elf_platform;
@@ -1064,6 +1072,11 @@ __cpuinit void cpu_probe(void) 
		c->srsets = 1;



	cpu_probe_vmbits(c);



#ifdef CONFIG_64BIT

	if (cpu == 0)

		__ua_limit = ~((1ull << cpu_vmbits) - 1);

#endif

}



__cpuinit void cpu_report(void)

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