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 set to 1 << 63 for 64-bit kernels on the theory that the TLB handlers cause a fault on all illegal accesses in the bottom half of the address space. This allows for more efficient code generation. 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@xxxxxxxxxxxxxxxxxx> --- This second version reworks the __UA_LIMIT part. arch/mips/include/asm/pgtable-64.h | 4 +- arch/mips/include/asm/processor.h | 40 +++++++++++++++++------------------ arch/mips/include/asm/uaccess.h | 2 +- 3 files changed, 22 insertions(+), 24 deletions(-) diff --git a/arch/mips/include/asm/pgtable-64.h b/arch/mips/include/asm/pgtable-64.h index 1be4b0f..82d881a 100644 --- a/arch/mips/include/asm/pgtable-64.h +++ b/arch/mips/include/asm/pgtable-64.h @@ -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 diff --git a/arch/mips/include/asm/processor.h b/arch/mips/include/asm/processor.h index 0d629bb..ead6928 100644 --- a/arch/mips/include/asm/processor.h +++ b/arch/mips/include/asm/processor.h @@ -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 diff --git a/arch/mips/include/asm/uaccess.h b/arch/mips/include/asm/uaccess.h index c2d53c1..476348f 100644 --- a/arch/mips/include/asm/uaccess.h +++ b/arch/mips/include/asm/uaccess.h @@ -35,7 +35,7 @@ #ifdef CONFIG_64BIT -#define __UA_LIMIT (- TASK_SIZE) +#define __UA_LIMIT (1ul << 63) #define __UA_ADDR ".dword" #define __UA_LA "dla" -- 1.7.2.3
