BMC/Intel-BMC/linux.git/arch/arm64/kernel/process.c, branch dev-4.10

arm64: Add hypervisor safe helper for checking constant capabilities

2016-11-16T17:50:51+00:00

The hypervisor may not have full access to the kernel data structures and hence cannot safely use cpus_have_cap() helper for checking the system capability. Add a safe helper for hypervisors to check a constant system capability, which *doesn't* fall back to checking the bitmap maintained by the kernel. With this, make the cpus_have_cap() only check the bitmask and force constant cap checks to use the new API for quicker checks. Cc: Robert Ritcher Cc: Tirumalesh Chalamarla Signed-off-by: Suzuki K Poulose Reviewed-by: Will Deacon Reviewed-by: Marc Zyngier Signed-off-by: Catalin Marinas

arm64: split thread_info from task stack

2016-11-11T18:25:46+00:00

This patch moves arm64's struct thread_info from the task stack into task_struct. This protects thread_info from corruption in the case of stack overflows, and makes its address harder to determine if stack addresses are leaked, making a number of attacks more difficult. Precise detection and handling of overflow is left for subsequent patches. Largely, this involves changing code to store the task_struct in sp_el0, and acquire the thread_info from the task struct. Core code now implements current_thread_info(), and as noted in this relies on offsetof(task_struct, thread_info) == 0, enforced by core code. This change means that the 'tsk' register used in entry.S now points to a task_struct, rather than a thread_info as it used to. To make this clear, the TI_* field offsets are renamed to TSK_TI_*, with asm-offsets appropriately updated to account for the structural change. Userspace clobbers sp_el0, and we can no longer restore this from the stack. Instead, the current task is cached in a per-cpu variable that we can safely access from early assembly as interrupts are disabled (and we are thus not preemptible). Both secondary entry and idle are updated to stash the sp and task pointer separately. Signed-off-by: Mark Rutland Tested-by: Laura Abbott Cc: AKASHI Takahiro Cc: Andy Lutomirski Cc: Ard Biesheuvel Cc: James Morse Cc: Kees Cook Cc: Suzuki K Poulose Cc: Will Deacon Signed-off-by: Catalin Marinas

arm64: prep stack walkers for THREAD_INFO_IN_TASK

2016-11-11T18:25:44+00:00

When CONFIG_THREAD_INFO_IN_TASK is selected, task stacks may be freed before a task is destroyed. To account for this, the stacks are refcounted, and when manipulating the stack of another task, it is necessary to get/put the stack to ensure it isn't freed and/or re-used while we do so. This patch reworks the arm64 stack walking code to account for this. When CONFIG_THREAD_INFO_IN_TASK is not selected these perform no refcounting, and this should only be a structural change that does not affect behaviour. Signed-off-by: Mark Rutland Tested-by: Laura Abbott Cc: AKASHI Takahiro Cc: Andy Lutomirski Cc: James Morse Cc: Will Deacon Signed-off-by: Catalin Marinas

arm64: fix show_regs fallout from KERN_CONT changes

2016-10-20T14:27:56+00:00

Recently in commit 4bcc595ccd80decb ("printk: reinstate KERN_CONT for printing continuation lines"), the behaviour of printk changed w.r.t. KERN_CONT. Now, KERN_CONT is mandatory to continue existing lines. Without this, prefixes are inserted, making output illegible, e.g. [ 1007.069010] pc : [] lr : [] pstate: 40000145 [ 1007.076329] sp : ffff000008d53ec0 [ 1007.079606] x29: ffff000008d53ec0 [ 1007.082797] x28: 0000000080c50018 [ 1007.086160] [ 1007.087630] x27: ffff000008e0c7f8 [ 1007.090820] x26: ffff80097631ca00 [ 1007.094183] [ 1007.095653] x25: 0000000000000001 [ 1007.098843] x24: 000000ea68b61cac [ 1007.102206] ... or when dumped with the userpace dmesg tool, which has slightly different implicit newline behaviour. e.g. [ 1007.069010] pc : [] lr : [] pstate: 40000145 [ 1007.076329] sp : ffff000008d53ec0 [ 1007.079606] x29: ffff000008d53ec0 [ 1007.082797] x28: 0000000080c50018 [ 1007.086160] [ 1007.087630] x27: ffff000008e0c7f8 [ 1007.090820] x26: ffff80097631ca00 [ 1007.094183] [ 1007.095653] x25: 0000000000000001 [ 1007.098843] x24: 000000ea68b61cac [ 1007.102206] We can't simply always use KERN_CONT for lines which may or may not be continuations. That causes line prefixes (e.g. timestamps) to be supressed, and the alignment of all but the first line will be broken. For even more fun, we can't simply insert some dummy empty-string printk calls, as GCC warns for an empty printk string, and even if we pass KERN_DEFAULT explcitly to silence the warning, the prefix gets swallowed unless there is an additional part to the string. Instead, we must manually iterate over pairs of registers, which gives us the legible output we want in either case, e.g. [ 169.771790] pc : [] lr : [] pstate: 40000145 [ 169.779109] sp : ffff000008d53ec0 [ 169.782386] x29: ffff000008d53ec0 x28: 0000000080c50018 [ 169.787650] x27: ffff000008e0c7f8 x26: ffff80097631de00 [ 169.792913] x25: 0000000000000001 x24: 00000027827b2cf4 Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Will Deacon

arm64: suspend: Reconfigure PSTATE after resume from idle

2016-10-20T08:50:54+00:00

The suspend/resume path in kernel/sleep.S, as used by cpu-idle, does not save/restore PSTATE. As a result of this cpufeatures that were detected and have bits in PSTATE get lost when we resume from idle. UAO gets set appropriately on the next context switch. PAN will be re-enabled next time we return from user-space, but on a preemptible kernel we may run work accessing user space before this point. Add code to re-enable theses two features in __cpu_suspend_exit(). We re-use uao_thread_switch() passing current. Signed-off-by: James Morse Cc: Lorenzo Pieralisi Signed-off-by: Will Deacon

arm64: use simpler API for random address requests

2016-10-11T22:06:32+00:00

Currently, all callers to randomize_range() set the length to 0 and calculate end by adding a constant to the start address. We can simplify the API to remove a bunch of needless checks and variables. Use the new randomize_addr(start, range) call to set the requested address. Link: http://lkml.kernel.org/r/20160803233913.32511-5-jason@lakedaemon.net Signed-off-by: Jason Cooper Acked-by: Will Deacon Acked-by: Kees Cook Cc: "Russell King - ARM Linux" Cc: Catalin Marinas Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

arm64: simplify sysreg manipulation

2016-09-09T10:43:50+00:00

A while back we added {read,write}_sysreg accessors to handle accesses to system registers, without the usual boilerplate asm volatile, temporary variable, etc. This patch makes use of these across arm64 to make code shorter and clearer. For sequences with a trailing ISB, the existing isb() macro is also used so that asm blocks can be removed entirely. A few uses of inline assembly for msr/mrs are left as-is. Those manipulating sp_el0 for the current thread_info value have special clobber requiremends. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Will Deacon Signed-off-by: Will Deacon

exit_thread: remove empty bodies

2016-05-21T00:58:30+00:00

Define HAVE_EXIT_THREAD for archs which want to do something in exit_thread. For others, let's define exit_thread as an empty inline. This is a cleanup before we change the prototype of exit_thread to accept a task parameter. [akpm@linux-foundation.org: fix mips] Signed-off-by: Jiri Slaby Cc: "David S. Miller" Cc: "H. Peter Anvin" Cc: "James E.J. Bottomley" Cc: Aurelien Jacquiot Cc: Benjamin Herrenschmidt Cc: Catalin Marinas Cc: Chen Liqin Cc: Chris Metcalf Cc: Chris Zankel Cc: David Howells Cc: Fenghua Yu Cc: Geert Uytterhoeven Cc: Guan Xuetao Cc: Haavard Skinnemoen Cc: Hans-Christian Egtvedt Cc: Heiko Carstens Cc: Helge Deller Cc: Ingo Molnar Cc: Ivan Kokshaysky Cc: James Hogan Cc: Jeff Dike Cc: Jesper Nilsson Cc: Jiri Slaby Cc: Jonas Bonn Cc: Koichi Yasutake Cc: Lennox Wu Cc: Ley Foon Tan Cc: Mark Salter Cc: Martin Schwidefsky Cc: Matt Turner Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Simek Cc: Mikael Starvik Cc: Paul Mackerras Cc: Peter Zijlstra Cc: Ralf Baechle Cc: Rich Felker Cc: Richard Henderson Cc: Richard Kuo Cc: Richard Weinberger Cc: Russell King Cc: Steven Miao Cc: Thomas Gleixner Cc: Tony Luck Cc: Vineet Gupta Cc: Will Deacon Cc: Yoshinori Sato Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

arm64: do not enforce strict 16 byte alignment to stack pointer

2016-05-12T13:20:49+00:00

copy_thread should not be enforcing 16 byte aligment and returning -EINVAL. Other architectures trap misaligned stack access with SIGBUS so arm64 should follow this convention, so remove the strict enforcement check. For example, currently clone(2) fails with -EINVAL when passing a misaligned stack and this gives little clue to what is wrong. Instead, it is arguable that a SIGBUS on the fist access to a misaligned stack allows one to figure out that it is a misaligned stack issue rather than trying to figure out why an unconventional (and undocumented) -EINVAL is being returned. Acked-by: Catalin Marinas Signed-off-by: Colin Ian King Signed-off-by: Will Deacon

arm64: kernel: Fix incorrect brk randomization

2016-05-11T10:38:10+00:00

This fixes two issues with the arm64 brk randomziation. First, the STACK_RND_MASK was being used incorrectly. The original code was: unsigned long range_end = base + (STACK_RND_MASK << PAGE_SHIFT) + 1; STACK_RND_MASK is 0x7ff (32-bit) or 0x3ffff (64-bit), with 4K pages where PAGE_SHIFT is 12: #define STACK_RND_MASK (test_thread_flag(TIF_32BIT) ? \ 0x7ff >> (PAGE_SHIFT - 12) : \ 0x3ffff >> (PAGE_SHIFT - 12)) This means the resulting offset from base would be 0x7ff0001 or 0x3ffff0001, which is wrong since it creates an unaligned end address. It was likely intended to be: unsigned long range_end = base + ((STACK_RND_MASK + 1) << PAGE_SHIFT) Which would result in offsets of 0x800000 (32-bit) and 0x40000000 (64-bit). However, even this corrected 32-bit compat offset (0x00800000) is much smaller than native ARM's brk randomization value (0x02000000): unsigned long arch_randomize_brk(struct mm_struct *mm) { unsigned long range_end = mm->brk + 0x02000000; return randomize_range(mm->brk, range_end, 0) ? : mm->brk; } So, instead of basing arm64's brk randomization on mistaken STACK_RND_MASK calculations, just use specific corrected values for compat (0x2000000) and native arm64 (0x40000000). Reviewed-by: Jon Medhurst Signed-off-by: Kees Cook [will: use is_compat_task() as suggested by tixy] Signed-off-by: Will Deacon