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Will Deacon 425fc47adb ARM: 6668/1: ptrace: remove single-step emulation code 
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 <nicolas.pitre@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
 		2011-02-23 17:24:22 +00:00
..
.gitignore [ARM] 5194/1: update .gitignore 2008-08-12 19:54:09 +01:00
Makefile Merge branch 'devel-stable' into devel 2011-01-06 22:33:32 +00:00
armksyms.c ARM: 6314/1: ftrace: allow build without frame pointers on ARM 2010-09-02 15:24:53 +01:00
arthur.c
…
asm-offsets.c arm: remove machine_desc.io_pg_offst and .phys_io 2010-10-20 00:27:46 -04:00
atags.c clean up atags exporting code 2008-05-30 10:33:49 +02:00
atags.h
…
bios32.c ARM: 6608/1: enable bridges in pci_common_init. 2011-02-23 17:24:14 +00:00
calls.S ARM: 6343/1: wire up fanotify and prlimit64 syscalls on ARM 2010-09-01 10:06:08 +01:00
compat.c ARM: deprecate support for old way to pass kernel parameters 2010-07-07 16:38:36 +02:00
compat.h ARM: deprecate support for old way to pass kernel parameters 2010-07-07 16:38:36 +02:00
crash_dump.c ARM: 6120/1: kdump: implement copy_oldmem_page() 2010-07-09 15:00:53 +01:00
crunch-bits.S [ARM] Move include/asm-arm/arch-* to arch/arm/*/include/mach 2008-08-07 09:55:48 +01:00
crunch.c ARM: Convert VFP/Crunch/XscaleCP thread_release() to exit_thread() 2009-12-18 14:53:41 +00:00
debug.S arm: return both physical and virtual addresses from addruart 2010-10-20 00:27:33 -04:00
dma-isa.c ARM: dma-isa: request cascade channel after registering it 2009-12-24 18:34:08 +00:00
dma.c ARM: dma: add /proc/dma support to arch/arm/kernel/dma.c 2010-04-14 13:13:30 +01:00
early_printk.c ARM: Add an earlyprintk debug console 2009-12-09 10:02:18 +00:00
ecard.c ARM: ecard: irq_data conversion. 2011-01-13 12:26:17 +01:00
ecard.h [ARM] rpc: ecard: remove deprecated ecard_address() and relatives 2008-07-03 14:25:58 +01:00
elf.c ARM: 5883/1: Revert "disable NX support for OABI-supporting kernels" 2010-01-18 14:12:11 +00:00
entry-armv.S Merge branch 'devel-stable' into devel 2011-01-06 22:33:32 +00:00
entry-common.S Merge branch 'clksrc' into devel 2011-01-05 18:09:03 +00:00
entry-header.S ARM: hw_breakpoint: disable preemption during debug exception handling 2010-12-06 11:55:56 +00:00
etm.c Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl 2010-10-22 10:52:56 -07:00
fiq.c Merge branch 'smp' into misc 2011-01-06 22:32:03 +00:00
ftrace.c ARM: ftrace: graph tracer + dynamic ftrace 2010-11-19 21:43:27 +05:30
head-common.S ARM: Defer lookup of machine_type to setup.c 2011-02-15 16:36:44 +00:00
head-nommu.S ARM: Defer lookup of machine_type to setup.c 2011-02-15 16:36:44 +00:00
head.S ARM: Defer lookup of machine_type to setup.c 2011-02-15 16:36:44 +00:00
hw_breakpoint.c ARM: hw_breakpoint: do not fail initcall if monitor mode is disabled 2010-12-15 12:31:03 +00:00
init_task.c Use new __init_task_data macro in arch init_task.c files. 2009-09-21 06:27:08 +02:00
io.c [ARM] Convert asm/io.h to linux/io.h 2008-09-06 12:10:45 +01:00
irq.c ARM: irq migration: ensure migration is handled safely 2011-02-23 17:24:16 +00:00
isa.c sysctl: Drop & in front of every proc_handler. 2009-11-18 08:37:40 -08:00
iwmmxt.S ARM: pxa: add iwmmx support for PJ4 2010-12-20 23:07:36 +08:00
kgdb.c kgdb,arm: fix register dump 2010-10-29 13:14:40 -05:00
kprobes-decode.c ARM: 6412/1: kprobes-decode: add support for MOVW instruction 2010-10-04 19:21:37 +01:00
kprobes.c Merge branch 'master' into export-slabh 2010-04-05 11:37:28 +09:00
leds.c ARM: move LED support code out of arch/arm/kernel/time.c 2010-02-15 21:39:12 +00:00
machine_kexec.c ARM: 6522/1: kexec: Add call to non-crashing cores through IPI 2010-12-04 11:02:04 +00:00
module.c ARM: improve module relocation fixup diagnostics 2011-02-23 17:24:14 +00:00
perf_event.c Merge branch 'devel' of master.kernel.org:/home/rmk/linux-2.6-arm 2011-01-06 16:50:35 -08:00
perf_event_v6.c ARM: 6521/1: perf: use raw_spinlock_t for pmu_lock 2010-12-04 11:18:08 +00:00
perf_event_v7.c ARM: 6521/1: perf: use raw_spinlock_t for pmu_lock 2010-12-04 11:18:08 +00:00
perf_event_xscale.c ARM: 6521/1: perf: use raw_spinlock_t for pmu_lock 2010-12-04 11:18:08 +00:00
pj4-cp0.c ARM: pxa: add iwmmx support for PJ4 2010-12-20 23:07:36 +08:00
pmu.c ARM: 6064/1: pmu: register IRQs at runtime 2010-05-17 11:53:57 +01:00
process.c ARM: 6619/1: nommu: avoid mapping vectors page when !CONFIG_MMU 2011-01-11 17:32:24 +00:00
ptrace.c ARM: 6668/1: ptrace: remove single-step emulation code 2011-02-23 17:24:22 +00:00
relocate_kernel.S ARM: 6497/1: kexec: Correct data alignment for CONFIG_THUMB2_KERNEL 2010-11-30 13:44:23 +00:00
return_address.c ARM: fix some sparse errors in generic ARM code 2011-02-23 17:24:12 +00:00
sched_clock.c ARM: sched_clock: make minsec argument to clocks_calc_mult_shift() zero 2011-01-11 16:44:02 +00:00
setup.c ARM: Defer lookup of machine_type to setup.c 2011-02-15 16:36:44 +00:00
signal.c ARM: 6668/1: ptrace: remove single-step emulation code 2011-02-23 17:24:22 +00:00
signal.h ARM: Fix signal restart issues with NX and OABI compat 2009-10-25 15:39:37 +00:00
smp.c Merge branch 'pgt' (early part) into devel 2011-01-06 22:33:19 +00:00
smp_scu.c Check whether the SCU was already initialised 2009-11-05 10:10:36 +00:00
smp_tlb.c ARM: SMP: split out software TLB maintainence broadcasting 2010-12-20 15:09:17 +00:00
smp_twd.c ARM: twd: ensure timer reload is reprogrammed on entry to periodic mode 2011-01-25 21:17:58 +00:00
stacktrace.c ARM: fix /proc/$PID/stack on SMP 2011-01-15 09:27:04 +00:00
swp_emulate.c ARM: 6396/1: Add SWP/SWPB emulation for ARMv7 processors 2010-11-04 15:45:24 +00:00
sys_arm.c Make do_execve() take a const filename pointer 2010-08-17 18:07:43 -07:00
sys_oabi-compat.c Mark arguments to certain syscalls as being const 2010-08-13 16:53:13 -07:00
tcm.c ARM: 6225/1: make TCM allocation static and common for all archs 2010-07-27 10:42:38 +01:00
tcm.h ARM: 5580/2: ARM TCM (Tightly-Coupled Memory) support v3 2009-09-15 22:11:05 +01:00
thumbee.c Fix the teehbr_read function prototype 2008-11-10 14:14:11 +00:00
time.c ARM: sched_clock: allow init_sched_clock() to be called early 2011-01-11 16:23:04 +00:00
traps.c ARM: 6668/1: ptrace: remove single-step emulation code 2011-02-23 17:24:22 +00:00
unwind.c ARM: 6468/1: backtrace: fix calculation of thread stack base 2010-11-07 16:12:37 +00:00
vmlinux.lds.S Merge branch 'misc' into devel 2011-01-06 22:32:52 +00:00
xscale-cp0.c ARM: Convert VFP/Crunch/XscaleCP thread_release() to exit_thread() 2009-12-18 14:53:41 +00:00