kernel/include/asm-generic, branch linux-4.1.y

EXPORT_SYMBOL() for asm

2018-03-01T03:09:37Z

[ Upstream commit 22823ab419d8ed884195cfa75483fd3a99bb1462 ] Add asm-usable variants of EXPORT_SYMBOL/EXPORT_SYMBOL_GPL. This commit just adds the default implementation; most of the architectures can simply add export.h to asm/Kbuild and start using from assembler. The rest needs to have their define everal macros and then explicitly include One area where the things might diverge from default is the alignment; normally it's 8 bytes on 64bit targets and 4 on 32bit ones, both for unsigned long and for struct kernel_symbol. Unfortunately, amd64 and m68k are unusual - m68k aligns to 2 bytes (for both) and amd64 aligns struct kernel_symbol to 16 bytes. For those we'll need asm/export.h to override the constants used by generic version - KSYM_ALIGN and KCRC_ALIGN for kernel_symbol and unsigned long resp. And no, __alignof__ would not do the trick - on amd64 __alignof__ of struct kernel_symbol is 8, not 16. More serious source of unpleasantness is treatment of function descriptors on architectures that have those. Things like ppc64, parisc, ia64, etc. need more than the address of the first insn to call an arbitrary function. As the result, their representation of pointers to functions is not the typical "address of the entry point" - it's an address of a small static structure containing all the required information (including the entry point, of course). Sadly, the asm-side conventions differ in what the function name refers to - entry point or the function descriptor. On ppc64 we do the latter; bar: .quad foo is what void (*bar)(void) = foo; turns into and the rare places where we need to explicitly work with the label of entry point are dealt with as DOTSYM(foo). For our purposes it's ideal - generic macros are usable. However, parisc would have foo and P%foo used for label of entry point and address of the function descriptor and bar: .long P%foo woudl be used instead. ia64 goes similar to parisc in that respect, except that there it's @fptr(foo) rather than P%foo. Such architectures need to define KSYM_FUNC that would turn a function name into whatever is needed to refer to function descriptor. What's more, on such architectures we need to know whether we are exporting a function or an object - in assembler we have to tell that explicitly, to decide whether we want EXPORT_SYMBOL(foo) produce e.g. __ksymtab_foo: .quad foo or __ksymtab_foo: .quad @fptr(foo) For that reason we introduce EXPORT_DATA_SYMBOL{,_GPL}(), to be used for exports of data objects. On normal architectures it's the same thing as EXPORT_SYMBOL{,_GPL}(), but on parisc-like ones they differ and the right one needs to be used. Most of the exports are functions, so we keep EXPORT_SYMBOL for those... Signed-off-by: Al Viro Signed-off-by: Sasha Levin

x86/kbuild: enable modversions for symbols exported from asm

2018-03-01T03:09:37Z

[ Upstream commit 334bb773876403eae3457d81be0b8ea70f8e4ccc ] Commit 4efca4ed ("kbuild: modversions for EXPORT_SYMBOL() for asm") adds modversion support for symbols exported from asm files. Architectures must include C-style declarations for those symbols in asm/asm-prototypes.h in order for them to be versioned. Add these declarations for x86, and an architecture-independent file that can be used for common symbols. With f27c2f6 reverting 8ab2ae6 ("default exported asm symbols to zero") we produce a scary warning on x86, this commit fixes that. Signed-off-by: Adam Borowski Tested-by: Kalle Valo Acked-by: Nicholas Piggin Tested-by: Peter Wu Tested-by: Oliver Hartkopp Signed-off-by: Michal Marek Signed-off-by: Sasha Levin

percpu: make this_cpu_generic_read() atomic w.r.t. interrupts

2017-11-06T04:54:28Z

[ Upstream commit e88d62cd4b2f0b1ae55e9008e79c2794b1fc914d ] As raw_cpu_generic_read() is a plain read from a raw_cpu_ptr() address, it's possible (albeit unlikely) that the compiler will split the access across multiple instructions. In this_cpu_generic_read() we disable preemption but not interrupts before calling raw_cpu_generic_read(). Thus, an interrupt could be taken in the middle of the split load instructions. If a this_cpu_write() or RMW this_cpu_*() op is made to the same variable in the interrupt handling path, this_cpu_read() will return a torn value. For native word types, we can avoid tearing using READ_ONCE(), but this won't work in all cases (e.g. 64-bit types on most 32-bit platforms). This patch reworks this_cpu_generic_read() to use READ_ONCE() where possible, otherwise falling back to disabling interrupts. Signed-off-by: Mark Rutland Cc: Arnd Bergmann Cc: Christoph Lameter Cc: Peter Zijlstra Cc: Pranith Kumar Cc: Tejun Heo Cc: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: stable@vger.kernel.org Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin

cpumask: fix spurious cpumask_of_node() on non-NUMA multi-node configs

2017-10-04T01:36:41Z

[ Upstream commit b339752d054fb32863418452dff350a1086885b1 ] When !NUMA, cpumask_of_node(@node) equals cpu_online_mask regardless of @node. The assumption seems that if !NUMA, there shouldn't be more than one node and thus reporting cpu_online_mask regardless of @node is correct. However, that assumption was broken years ago to support DISCONTIGMEM and whether a system has multiple nodes or not is separately controlled by NEED_MULTIPLE_NODES. This means that, on a system with !NUMA && NEED_MULTIPLE_NODES, cpumask_of_node() will report cpu_online_mask for all possible nodes, indicating that the CPUs are associated with multiple nodes which is an impossible configuration. This bug has been around forever but doesn't look like it has caused any noticeable symptoms. However, it triggers a WARN recently added to workqueue to verify NUMA affinity configuration. Fix it by reporting empty cpumask on non-zero nodes if !NUMA. Signed-off-by: Tejun Heo Reported-and-tested-by: Geert Uytterhoeven Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

asm-generic: make get_user() clear the destination on errors

2016-10-03T01:12:56Z

[ Upstream commit 9ad18b75c2f6e4a78ce204e79f37781f8815c0fa ] both for access_ok() failures and for faults halfway through Cc: stable@vger.kernel.org Signed-off-by: Al Viro Signed-off-by: Sasha Levin

asm-generic: {get,put}_user ptr argument evaluate only 1 time

2016-10-03T01:12:48Z

[ Upstream commit a02613a4ba679eacec8251976d02809d533fa717 ] Current implemantation ptr argument evaluate 2 times. It'll be an unexpected result. Changes v5: Remove unnecessary const. Changes v4: Temporary pointer type change to const void* Changes v3: Some build error fix. Changes v2: Argument x protect. Signed-off-by: Yoshinori Sato Signed-off-by: Sasha Levin

asm-generic: make copy_from_user() zero the destination properly

2016-10-03T00:32:37Z

[ Upstream commit 2545e5da080b4839dd859e3b09343a884f6ab0e3 ] ... in all cases, including the failing access_ok() Note that some architectures using asm-generic/uaccess.h have __copy_from_user() not zeroing the tail on failure halfway through. This variant works either way. Cc: stable@vger.kernel.org Signed-off-by: Al Viro Signed-off-by: Sasha Levin

vmlinux.lds: account for destructor sections

2016-08-06T16:59:11Z

[ Upstream commit e41f501d391265ff568f3e49d6128cc30856a36f ] If CONFIG_KASAN is enabled and gcc is configured with --disable-initfini-array and/or gold linker is used, gcc emits .ctors/.dtors and .text.startup/.text.exit sections instead of .init_array/.fini_array. .dtors section is not explicitly accounted in the linker script and messes vvar/percpu layout. We want: ffffffff822bfd80 D _edata ffffffff822c0000 D __vvar_beginning_hack ffffffff822c0000 A __vvar_page ffffffff822c0080 0000000000000098 D vsyscall_gtod_data ffffffff822c1000 A __init_begin ffffffff822c1000 D init_per_cpu__irq_stack_union ffffffff822c1000 A __per_cpu_load ffffffff822d3000 D init_per_cpu__gdt_page We got: ffffffff8279a600 D _edata ffffffff8279b000 A __vvar_page ffffffff8279c000 A __init_begin ffffffff8279c000 D init_per_cpu__irq_stack_union ffffffff8279c000 A __per_cpu_load ffffffff8279e000 D __vvar_beginning_hack ffffffff8279e080 0000000000000098 D vsyscall_gtod_data ffffffff827ae000 D init_per_cpu__gdt_page This happens because __vvar_page and .vvar get different addresses in arch/x86/kernel/vmlinux.lds.S: . = ALIGN(PAGE_SIZE); __vvar_page = .; .vvar : AT(ADDR(.vvar) - LOAD_OFFSET) { /* work around gold bug 13023 */ __vvar_beginning_hack = .; Discard .dtors/.fini_array/.text.exit, since we don't call dtors. Merge .text.startup into init text. Link: http://lkml.kernel.org/r/1467386363-120030-1-git-send-email-dvyukov@google.com Signed-off-by: Dmitry Vyukov Reviewed-by: Andrey Ryabinin Cc: [4.0+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

SIGNAL: Move generic copy_siginfo() to signal.h

2016-06-06T23:12:20Z

[ Upstream commit ca9eb49aa9562eaadf3cea071ec7018ad6800425 ] The generic copy_siginfo() is currently defined in asm-generic/siginfo.h, after including uapi/asm-generic/siginfo.h which defines the generic struct siginfo. However this makes it awkward for an architecture to use it if it has to define its own struct siginfo (e.g. MIPS and potentially IA64), since it means that asm-generic/siginfo.h can only be included after defining the arch-specific siginfo, which may be problematic if the arch-specific definition needs definitions from uapi/asm-generic/siginfo.h. It is possible to work around this by first including uapi/asm-generic/siginfo.h to get the constants before defining the arch-specific siginfo, and include asm-generic/siginfo.h after. However uapi headers can't be included by other uapi headers, so that first include has to be in an ifdef __kernel__, with the non __kernel__ case including the non-UAPI header instead. Instead of that mess, move the generic copy_siginfo() definition into linux/signal.h, which allows an arch-specific uapi/asm/siginfo.h to include asm-generic/siginfo.h and define the arch-specific siginfo, and for the generic copy_siginfo() to see that arch-specific definition. Signed-off-by: James Hogan Cc: Arnd Bergmann Cc: Ralf Baechle Cc: Petr Malat Cc: Tony Luck Cc: Fenghua Yu Cc: Christopher Ferris Cc: linux-arch@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: linux-ia64@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: # 4.0- Patchwork: https://patchwork.linux-mips.org/patch/12478/ Signed-off-by: Ralf Baechle Signed-off-by: Sasha Levin

bitops: Do not default to __clear_bit() for __clear_bit_unlock()

2016-04-18T12:51:05Z

[ Upstream commit f75d48644c56a31731d17fa693c8175328957e1d ] __clear_bit_unlock() is a special little snowflake. While it carries the non-atomic '__' prefix, it is specifically documented to pair with test_and_set_bit() and therefore should be 'somewhat' atomic. Therefore the generic implementation of __clear_bit_unlock() cannot use the fully non-atomic __clear_bit() as a default. If an arch is able to do better; is must provide an implementation of __clear_bit_unlock() itself. Specifically, this came up as a result of hackbench livelock'ing in slab_lock() on ARC with SMP + SLUB + !LLSC. The issue was incorrect pairing of atomic ops. slab_lock() -> bit_spin_lock() -> test_and_set_bit() slab_unlock() -> __bit_spin_unlock() -> __clear_bit() The non serializing __clear_bit() was getting "lost" 80543b8e: ld_s r2,[r13,0] <--- (A) Finds PG_locked is set 80543b90: or r3,r2,1 <--- (B) other core unlocks right here 80543b94: st_s r3,[r13,0] <--- (C) sets PG_locked (overwrites unlock) Fixes ARC STAR 9000817404 (and probably more). Reported-by: Vineet Gupta Tested-by: Vineet Gupta Signed-off-by: Peter Zijlstra (Intel) Cc: Andrew Morton Cc: Christoph Lameter Cc: David Rientjes Cc: Helge Deller Cc: James E.J. Bottomley Cc: Joonsoo Kim Cc: Linus Torvalds Cc: Noam Camus Cc: Paul E. McKenney Cc: Pekka Enberg Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20160309114054.GJ6356@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin