kernel.git/arch/arm/mm/init.c, branch linux-4.17.y

ARM: 8780/1: ftrace: Only set kernel memory back to read-only after boot

2018-08-24T11:07:07Z

[ Upstream commit b4c7e2bd2eb4764afe3af9409ff3b1b87116fa30 ] Dynamic ftrace requires modifying the code segments that are usually set to read-only. To do this, a per arch function is called both before and after the ftrace modifications are performed. The "before" function will set kernel code text to read-write to allow for ftrace to make the modifications, and the "after" function will set the kernel code text back to "read-only" to keep the kernel code text protected. The issue happens when dynamic ftrace is tested at boot up. The test is done before the kernel code text has been set to read-only. But the "before" and "after" calls are still performed. The "after" call will change the kernel code text to read-only prematurely, and other boot code that expects this code to be read-write will fail. The solution is to add a variable that is set when the kernel code text is expected to be converted to read-only, and make the ftrace "before" and "after" calls do nothing if that variable is not yet set. This is similar to the x86 solution from commit 162396309745 ("ftrace, x86: make kernel text writable only for conversions"). Link: http://lkml.kernel.org/r/20180620212906.24b7b66e@vmware.local.home Reported-by: Stefan Agner Tested-by: Stefan Agner Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Russell King Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

ARM: simplify and fix linker script for TCM

2018-03-10T01:20:43Z

Let's put the TCM stuff in the __init section directly. No need for a separately freed memory area. Remove redundant linker sections, as well as comments that were more confusing than no comments at all. Finally make it XIP compatible by using LOAD_OFFSET in the section LMA specification. Signed-off-by: Nicolas Pitre Tested-by: Chris Brandt

ARM: 8737/1: mm: dump: add checking for writable and executable

2018-01-21T15:32:20Z

Page mappings with full RWX permissions are a security risk. x86, arm64 has an option to walk the page tables and dump any bad pages. (1404d6f13e47 ("arm64: dump: Add checking for writable and exectuable pages")) Add a similar implementation for arm. Reviewed-by: Kees Cook Tested-by: Laura Abbott Reviewed-by: Laura Abbott Signed-off-by: Jinbum Park Signed-off-by: Russell King

Merge branch 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm

2017-11-26T23:03:49Z

Pull ARM fixes from Russell King: - LPAE fixes for kernel-readonly regions - Fix for get_user_pages_fast on LPAE systems - avoid tying decompressor to a particular platform if DEBUG_LL is enabled - BUG if we attempt to return to userspace but the to-be-restored PSR value keeps us in privileged mode (defeating an issue that ftracetest found) * 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm: ARM: BUG if jumping to usermode address in kernel mode ARM: 8722/1: mm: make STRICT_KERNEL_RWX effective for LPAE ARM: 8721/1: mm: dump: check hardware RO bit for LPAE ARM: make decompressor debug output user selectable ARM: fix get_user_pages_fast

ARM: 8722/1: mm: make STRICT_KERNEL_RWX effective for LPAE

2017-11-21T15:10:07Z

Currently, for ARM kernels with CONFIG_ARM_LPAE and CONFIG_STRICT_KERNEL_RWX enabled, the 2MiB pages mapping the kernel code and rodata are writable. They are marked read-only in a software bit (L_PMD_SECT_RDONLY) but the hardware read-only bit is not set (PMD_SECT_AP2). For user mappings, the logic that propagates the software bit to the hardware bit is in set_pmd_at(); but for the kernel, section_update() writes the PMDs directly, skipping this logic. The fix is to set PMD_SECT_AP2 for read-only sections in section_update(), at the same time as L_PMD_SECT_RDONLY. Fixes: 1e3479225acb ("ARM: 8275/1: mm: fix PMD_SECT_RDONLY undeclared compile error") Signed-off-by: Philip Derrin Reported-by: Neil Dick Tested-by: Neil Dick Tested-by: Laura Abbott Reviewed-by: Kees Cook Cc: stable@vger.kernel.org Signed-off-by: Russell King

ARM: 8696/1: mm: Remove dead code in mem_init()

2017-09-28T10:13:04Z

The code in question checks memory constrains to set default policy for overcommit; however we support page size of 4K only thus condition is always evaluated to false. Remove that dead code. Signed-off-by: Vladimir Murzin Signed-off-by: Russell King

ARM: 8672/1: mm: remove tasklist locking from update_sections_early()

2017-04-26T09:59:36Z

The below backtrace can be observed on -rt kernel with CONFIG_DEBUG_MODULE_RONX (4.9 kernel CONFIG_DEBUG_RODATA) option enabled: BUG: sleeping function called from invalid context at kernel/locking/rtmutex.c:993 in_atomic(): 1, irqs_disabled(): 128, pid: 14, name: migration/0 1 lock held by migration/0/14: #0: (tasklist_lock){+.+...}, at: [] update_sections_early+0x24/0xdc irq event stamp: 38 hardirqs last enabled at (37): [] _raw_spin_unlock_irq+0x24/0x68 hardirqs last disabled at (38): [] multi_cpu_stop+0xd8/0x138 softirqs last enabled at (0): [] copy_process.part.5+0x238/0x1b64 softirqs last disabled at (0): [< (null)>] (null) Preemption disabled at: [] cpu_stopper_thread+0x80/0x10c CPU: 0 PID: 14 Comm: migration/0 Not tainted 4.9.21-rt16-02220-g49e319c #15 Hardware name: Generic DRA74X (Flattened Device Tree) [] (unwind_backtrace) from [] (show_stack+0x10/0x14) [] (show_stack) from [] (dump_stack+0xa8/0xd4) [] (dump_stack) from [] (___might_sleep+0x1bc/0x2ac) [] (___might_sleep) from [] (__rt_spin_lock+0x1c/0x30) [] (__rt_spin_lock) from [] (rt_read_lock+0x54/0x68) [] (rt_read_lock) from [] (update_sections_early+0x24/0xdc) [] (update_sections_early) from [] (__fix_kernmem_perms+0x10/0x1c) [] (__fix_kernmem_perms) from [] (multi_cpu_stop+0x100/0x138) [] (multi_cpu_stop) from [] (cpu_stopper_thread+0x88/0x10c) [] (cpu_stopper_thread) from [] (smpboot_thread_fn+0x174/0x31c) [] (smpboot_thread_fn) from [] (kthread+0xf0/0x108) [] (kthread) from [] (ret_from_fork+0x14/0x3c) Freeing unused kernel memory: 1024K (c0d00000 - c0e00000) The stop_machine() is called with cpus = NULL from fix_kernmem_perms() and mark_rodata_ro() which means only one CPU will execute update_sections_early() while all other CPUs will spin and wait. Hence, it's safe to remove tasklist locking from update_sections_early(). As part of this change also mark functions which are local to this module as static. Signed-off-by: Grygorii Strashko Acked-by: Laura Abbott Acked-by: Kees Cook Signed-off-by: Russell King

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:35Z

We are going to split out of , which will have to be picked up from other headers and a couple of .c files. Create a trivial placeholder file that just maps to to make this patch obviously correct and bisectable. Include the new header in the files that are going to need it. Acked-by: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar

sched/headers: Prepare for new header dependencies before moving code to

2017-03-02T07:42:29Z

Merge branch 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

2017-02-28T19:50:53Z

Pull ARM updates from Russell King: - nommu updates from Afzal Mohammed cleaning up the vectors support - allow DMA memory "mapping" for nommu Benjamin Gaignard - fixing a correctness issue with R_ARM_PREL31 relocations in the module linker - add strlen() prototype for the decompressor - support for DEBUG_VIRTUAL from Florian Fainelli - adjusting memory bounds after memory reservations have been registered - unipher cache handling updates from Masahiro Yamada - initrd and Thumb Kconfig cleanups * 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (23 commits) ARM: mm: round the initrd reservation to page boundaries ARM: mm: clean up initrd initialisation ARM: mm: move initrd init code out of arm_memblock_init() ARM: 8655/1: improve NOMMU definition of pgprot_*() ARM: 8654/1: decompressor: add strlen prototype ARM: 8652/1: cache-uniphier: clean up active way setup code ARM: 8651/1: cache-uniphier: include instead of ARM: 8650/1: module: handle negative R_ARM_PREL31 addends correctly ARM: 8649/2: nommu: remove Hivecs configuration is asm ARM: 8648/2: nommu: display vectors base ARM: 8647/2: nommu: dynamic exception base address setting ARM: 8646/1: mmu: decouple VECTORS_BASE from Kconfig ARM: 8644/1: Reduce "CPU: shutdown" message to debug level ARM: 8641/1: treewide: Replace uses of virt_to_phys with __pa_symbol ARM: 8640/1: Add support for CONFIG_DEBUG_VIRTUAL ARM: 8639/1: Define KERNEL_START and KERNEL_END ARM: 8638/1: mtd: lart: Rename partition defines to be prefixed with PART_ ARM: 8637/1: Adjust memory boundaries after reservations ARM: 8636/1: Cleanup sanity_check_meminfo ARM: add CPU_THUMB_CAPABLE to indicate possible Thumb support ...