linux-stable.git/arch/arm/include/asm/processor.h, branch linux-3.4.y

ARM: 7791/1: a.out: remove partial a.out support

2014-04-14T13:44:21+00:00

commit acfdd4b1f7590d02e9bae3b73bdbbc4a31b05d38 upstream.

a.out support on ARM requires that argc, argv and envp are passed in
r0-r2 respectively, which requires hacking load_aout_binary to
prevent argc being clobbered by the return code. Whilst mainline kernels
do set the registers up in start_thread, the aout loader has never
carried the hack in mainline.

Initialising the registers in this way actually goes against the libc
expectations for ELF binaries, where argc, argv and envp are passed on
the stack, with r0 being used to hold a pointer to an exit function for
cleaning up after the dynamic linker if required. If the pointer is
NULL, then it is ignored. When execing an ELF binary, Linux currently
zeroes r0, then sets it to argc and then finally clobbers it with the
return value of the execve syscall, so we actually end up with:

	r0 = 0
	stack[0] = argc
	r1 = stack[1] = argv
	r2 = stack[2] = envp

libc treats r1 and r2 as undefined. The clobbering of r0 by sys_execve
works for user-spawned threads, but when executing an ELF binary from a
kernel thread (via call_usermodehelper), the execve is performed on the
ret_from_fork path, which restores r0 from the saved pt_regs, resulting
in argc being presented to the C library. This has horrible consequences
when the application exits, since we have an exit function registered
using argc, resulting in a jump to hyperspace.

This patch solves the problem by removing the partial a.out support from
arch/arm/ altogether.

Cc: Ashish Sangwan 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King 
[bwh: Backported to 3.2:
 - Adjust context
 - Adjust uapi filename]
Signed-off-by: Ben Hutchings 
[yangyl: Backported to 3.4: Adjust context]
Signed-off-by: Yang Yingliang 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'for-linus' of git://git.linaro.org/people/rmk/linux-arm

2012-03-29T23:53:48+00:00

Pull more ARM updates from Russell King.

This got a fair number of conflicts with the  split, but
also with some other sparse-irq and header file include cleanups.  They
all looked pretty trivial, though.

* 'for-linus' of git://git.linaro.org/people/rmk/linux-arm: (59 commits)
  ARM: fix Kconfig warning for HAVE_BPF_JIT
  ARM: 7361/1: provide XIP_VIRT_ADDR for no-MMU builds
  ARM: 7349/1: integrator: convert to sparse irqs
  ARM: 7259/3: net: JIT compiler for packet filters
  ARM: 7334/1: add jump label support
  ARM: 7333/2: jump label: detect %c support for ARM
  ARM: 7338/1: add support for early console output via semihosting
  ARM: use set_current_blocked() and block_sigmask()
  ARM: exec: remove redundant set_fs(USER_DS)
  ARM: 7332/1: extract out code patch function from kprobes
  ARM: 7331/1: extract out insn generation code from ftrace
  ARM: 7330/1: ftrace: use canonical Thumb-2 wide instruction format
  ARM: 7351/1: ftrace: remove useless memory checks
  ARM: 7316/1: kexec: EOI active and mask all interrupts in kexec crash path
  ARM: Versatile Express: add NO_IOPORT
  ARM: get rid of asm/irq.h in asm/prom.h
  ARM: 7319/1: Print debug info for SIGBUS in user faults
  ARM: 7318/1: gic: refactor irq_start assignment
  ARM: 7317/1: irq: avoid NULL check in for_each_irq_desc loop
  ARM: 7315/1: perf: add support for the Cortex-A7 PMU
  ...

Disintegrate asm/system.h for ARM

2012-03-28T17:30:01+00:00

Disintegrate asm/system.h for ARM.

Signed-off-by: David Howells 
cc: Russell King 
cc: linux-arm-kernel@lists.infradead.org

ARM: exec: remove redundant set_fs(USER_DS)

2012-03-24T09:38:55+00:00

The address limit is already set in flush_old_exec() so this
set_fs(USER_DS) is redundant.

Signed-off-by: Mathias Krause 
Signed-off-by: Andrew Morton 
Signed-off-by: Russell King

ARM: 7327/1: need to include asm/system.h in asm/processor.h

2012-02-15T21:10:49+00:00

For files that include asm/processor.h but not asm/system.h:

arch/arm/mach-msm/include/mach/uncompress.h: In function 'putc':
arch/arm/mach-msm/include/mach/uncompress.h:48:3: error: implicit declaration of function 'smp_mb' [-Werror=implicit-function-declaration]

In this case, smp_mb() is from the cpu_relax() call in the msm putc().

It likely went uncaught when the uncompress.h change went in since the
defconfig didn't enable that code path, but later changes (e76f4750f4:
ARM: debug: arrange Kconfig options more logically) resulted in the
option being on for msm_defconfig and thus exposed it.

Signed-off-by: Olof Johansson 
Signed-off-by: Russell King

ARM: 7169/1: topdown mmap support

2011-12-06T11:15:25+00:00

Similar to other architectures, this adds topdown mmap support in user
process address space allocation policy. This allows mmap sizes greater
than 2GB. This support is largely copied from MIPS and the generic
implementations.

The address space randomization is moved into arch_pick_mmap_layout.

Tested on V-Express with ubuntu and a mmap test from here:
https://bugs.launchpad.net/bugs/861296

Signed-off-by: Rob Herring 
Acked-by: Nicolas Pitre 
Signed-off-by: Russell King

Merge branch 'misc' into devel

2011-03-16T23:35:25+00:00

Conflicts:
	arch/arm/Kconfig

ARM: 6784/1: errata: no automatic Store Buffer drain on Cortex-A9

2011-03-09T21:40:18+00:00

On revisions of the Cortex-A9 prior to r2p0, the Store Buffer does not
have any automatic draining mechanism and therefore a livelock may occur
if an external agent continuously polls a memory location waiting to
observe an update.

This workaround defines cpu_relax() as smp_mb(), preventing correctly
written polling loops from denying visibility of updates to memory.

Acked-by: Catalin Marinas 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: 6668/1: ptrace: remove single-step emulation code

2011-02-23T17:24:22+00:00

PTRACE_SINGLESTEP is a ptrace request designed to offer single-stepping
support to userspace when the underlying architecture has hardware
support for this operation.

On ARM, we set arch_has_single_step() to 1 and attempt to emulate hardware
single-stepping by disassembling the current instruction to determine the
next pc and placing a software breakpoint on that location.

Unfortunately this has the following problems:

1.) Only a subset of ARMv7 instructions are supported
2.) Thumb-2 is unsupported
3.) The code is not SMP safe

We could try to fix this code, but it turns out that because of the above
issues it is rarely used in practice.  GDB, for example, uses PTRACE_POKETEXT
and PTRACE_PEEKTEXT to manage breakpoints itself and does not require any
kernel assistance.

This patch removes the single-step emulation code from ptrace meaning that
the PTRACE_SINGLESTEP request will return -EIO on ARM. Portable code must
check the return value from a ptrace call and handle the failure gracefully.

Acked-by: Nicolas Pitre 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King

ARM: 6357/1: hw-breakpoint: add new ptrace requests for hw-breakpoint interaction

2010-09-08T09:05:00+00:00

For debuggers to take advantage of the hw-breakpoint framework in the kernel,
it is necessary to expose the API calls via a ptrace interface.

This patch exposes the hardware breakpoints framework as a collection of
virtual registers, accesible using PTRACE_SETHBPREGS and PTRACE_GETHBPREGS
requests. The breakpoints are stored in the debug_info struct of the running
thread.

Cc: Frederic Weisbecker 
Cc: S. Karthikeyan 
Signed-off-by: Will Deacon 
Signed-off-by: Russell King