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@xxxxxxxxxxxxxxxxxx> --- The third time should be the charm here. Only change from the first two is __UA_LIMIT. arch/mips/include/asm/pgtable-64.h | 4 +- arch/mips/include/asm/processor.h | 40 +++++++++++++++++------------------ arch/mips/include/asm/uaccess.h | 4 ++- arch/mips/kernel/cpu-probe.c | 13 +++++++++++ 4 files changed, 37 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..653a412 100644 --- a/arch/mips/include/asm/uaccess.h +++ b/arch/mips/include/asm/uaccess.h @@ -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" diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c index b9378cd..70f0aa2 100644 --- a/arch/mips/kernel/cpu-probe.c +++ b/arch/mips/kernel/cpu-probe.c @@ -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 @@ -983,6 +985,12 @@ 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; @@ -1060,6 +1068,11 @@ __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) -- 1.7.2.3
