Messages in this thread | | | Subject | Re: [PATCH] MIPS: Always page align TASK_SIZE | From | Harvey Hunt <> | Date | Mon, 8 Feb 2016 14:26:43 -0800 |
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On 02/08/2016 02:08 PM, David Daney wrote: > 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! >
Yeah, I noticed that. I'll just drop this patch...
Thanks,
Harvey
> >> >>> >>> >>>>> >>>>>> #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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