| Message ID | 1462376056-12388-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/arch/s390/mm/mmap.c b/arch/s390/mm/mmap.c index d008f638..179a2c2 100644 --- a/arch/s390/mm/mmap.c +++ b/arch/s390/mm/mmap.c @@ -183,7 +183,10 @@ unsigned long randomize_et_dyn(void) { unsigned long base; - base = (STACK_TOP / 3 * 2) & (~mmap_align_mask << PAGE_SHIFT); + base = STACK_TOP / 3 * 2; + if (!is_32bit_task()) + /* Align to 4GB */ + base &= ~((1UL << 32) - 1); return base + mmap_rnd(); }
This is a note to let you know that I have just added a patch titled s390/mm: align 64-bit PIE binaries to 4GB to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree which can be found at: https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-3.19.y-queue This patch is scheduled to be released in version 3.19.8-ckt21. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.19.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 6bb57bb08175b353677ae73718e900ec9331d17d Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky <schwidefsky@de.ibm.com> Date: Thu, 12 Feb 2015 14:17:52 +0100 Subject: s390/mm: align 64-bit PIE binaries to 4GB commit 4ba2815d3bf38d6a959d2d11b08cf862550dcfcc upstream. The base address (STACK_TOP / 3 * 2) for a 64-bit program is two thirds into the 4GB segment at 0x2aa00000000. The randomization added on z13 can eat another 1GB of the remaining 1.33GB to the next 4GB boundary. In the worst case 300MB are left for the executable + bss which may cross into the next 4GB segment. This is bad for branch prediction, therefore align the base address to 4GB to give the program more room before it crosses the 4GB boundary. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/s390/mm/mmap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) -- 2.7.4