Messages in this thread | | | Date | Mon, 8 Feb 2016 14:08:17 -0800 | From | David Daney <> | Subject | Re: [PATCH] MIPS: Always page align TASK_SIZE |
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On 02/08/2016 01:48 PM, Harvey Hunt wrote: > Hi Joshua, > > On 02/08/2016 01:35 PM, Joshua Kinard wrote: >> On 02/08/2016 13:15, Harvey Hunt wrote: >>> Hi David, >>> >>> On 02/08/2016 10:11 AM, David Daney wrote: >>>> On 02/08/2016 10:05 AM, Harvey Hunt wrote: >>>>> STACK_TOP_MAX is aligned on a 32k boundary. When __bprm_mm_init() >>>>> creates an >>>>> initial stack for a process, it does so using STACK_TOP_MAX as the end >>>>> of the >>>>> vma. A process's arguments and environment information are placed on >>>>> the stack >>>>> and then the stack is relocated and aligned on a page boundary. When >>>>> using a 32 >>>>> bit kernel with 64k pages, the relocated stack has the process's args >>>>> erroneously stored in the middle of the stack. This means that >>>>> processes >>>>> receive no arguments or environment variables, preventing them from >>>>> running >>>>> correctly. >>>>> >>>>> Fix this by aligning TASK_SIZE on a page boundary. >>>>> >>>>> Signed-off-by: Harvey Hunt <harvey.hunt@imgtec.com> >>>>> Cc: David Daney <david.daney@cavium.com> >>>>> Cc: Paul Burton <paul.burton@imgtec.com> >>>>> Cc: James Hogan <james.hogan@imgtec.com> >>>>> Cc: linux-kernel@vger.kernel.org >>>>> --- >>>>> arch/mips/include/asm/processor.h | 6 +++--- >>>>> 1 file changed, 3 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/arch/mips/include/asm/processor.h >>>>> b/arch/mips/include/asm/processor.h >>>>> index 3f832c3..b618b40 100644 >>>>> --- a/arch/mips/include/asm/processor.h >>>>> +++ b/arch/mips/include/asm/processor.h >>>>> @@ -39,13 +39,13 @@ extern unsigned int vced_count, vcei_count; >>>>> #ifdef CONFIG_32BIT >>>>> #ifdef CONFIG_KVM_GUEST >>>>> /* User space process size is limited to 1GB in KVM Guest Mode */ >>>>> -#define TASK_SIZE 0x3fff8000UL >>>>> +#define TASK_SIZE (0x40000000UL - PAGE_SIZE) >>>>> #else >>>>> /* >>>>> * User space process size: 2GB. This is hardcoded into a few >>>>> places, >>>>> * so don't change it unless you know what you are doing. >>>>> */ >>>>> -#define TASK_SIZE 0x7fff8000UL >>>>> +#define TASK_SIZE (0x7fff8000UL & PAGE_SIZE) >>>> >>>> Can you check your math here. This doesn't seem correct. >>> >>> Thanks for spotting that - it should have been: >>> >>> (0x7fff8000UL & PAGE_MASK) >>> >>> I'll do a v2 now. >>> >> >> FYI, TASK_SIZE was recently changed to 0x80000000UL in commit >> 7f8ca9cb1ed3 on >> the linux-mips.org tree. > > Thanks, I'll rebase.
You may find that in rebasing, suddenly you have a completely empty patch!
> >> >> >>>> >>>>> #endif >>>>> >>>>> #define STACK_TOP_MAX TASK_SIZE >>>>> @@ -62,7 +62,7 @@ extern unsigned int vced_count, vcei_count; >>>>> * support 16TB; the architectural reserve for future expansion is >>>>> * 8192EB ... >>>>> */ >>>>> -#define TASK_SIZE32 0x7fff8000UL >>>>> +#define TASK_SIZE32 (0x7fff8000UL & PAGE_SIZE) >>>> >>>> Same here. >>> >>> As above. >>> >>>> >>>>> #define TASK_SIZE64 0x10000000000UL >>>>> #define TASK_SIZE (test_thread_flag(TIF_32BIT_ADDR) ? TASK_SIZE32 : >>>>> TASK_SIZE64) >>>>> #define STACK_TOP_MAX TASK_SIZE64 >>>>> >>>> >>> >>> Thanks, >>> >>> Harvey >>> >>> >> >>
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