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

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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: David Daney <ddaney@caviumnetworks.com>
To: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/1701/
This commit is contained in:
David Daney 2010-10-14 11:32:33 -07:00 • committed by Ralf Baechle
parent 18d693b359
commit 949e51bea3
4 changed files with 37 additions and 24 deletions
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40
arch/mips/include/asm/processor.h
View file

@ -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