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2011-07-13ARM: kprobes: Decode 16-bit Thumb PUSH and POP instructionsJon Medhurst
These instructions are equivalent to stmdb sp!,{r0-r7,lr} ldmdb sp!,{r0-r7,pc} and we emulate them by transforming them into the 32-bit Thumb instructions stmdb r9!,{r0-r7,r8} ldmdb r9!,{r0-r7,r8} This is simpler, and almost certainly executes faster, than writing simulation functions. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Decode 16-bit Thumb CBZ and bit manipulation instructionsJon Medhurst
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Decode 16-bit Thumb PC- and SP-relative address instructionsJon Medhurst
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Decode 16-bit Thumb load and store instructionsJon Medhurst
Most of these instructions only operate on the low registers R0-R7 so they can make use of t16_emulate_loregs_rwflags. The instructions which use SP or PC for addressing have their own simulation functions. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Decode 16-bit Thumb special data instructionsJon Medhurst
These data-processing instructions operate on the full range of CPU registers, so to simulate them we have to modify the registers used by the instruction. We can't make use of the decoding table framework to do this because the registers aren't encoded cleanly in separate nibbles, therefore we need a custom decode function. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Decode 16-bit Thumb BX and BLX instructionsJon Medhurst
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Add bx_write_pc()Jon Medhurst
This writes a value to PC, with interworking. I.e. switches to Thumb or ARM mode depending on the state of the least significant bit. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Decode 16-bit Thumb data-processing instructionsJon Medhurst
These instructions only operate on the low registers R0-R7, therefore it is possible to emulate them by executing the original instruction unaltered if we restore and save these registers. This is what t16_emulate_loregs does. Some of these instructions don't update the PSR when they execute in an IT block, so there are two flavours of emulation functions: t16_emulate_loregs_{noit}rwflags Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Decode 16-bit Thumb hint instructionsJon Medhurst
For hints which may have observable effects, like SEV (send event), we use kprobe_emulate_none which emulates the hint by executing the original instruction. For NOP we simulate the instruction using kprobe_simulate_nop, which does nothing. As probes execute with interrupts disabled this is also used for hints which may block for an indefinite time, like WFE (wait for event). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Infrastructure for table driven decoding of CPU instructionsJon Medhurst
The existing ARM instruction decoding functions are a mass of if/else code. Rather than follow this pattern for Thumb instruction decoding this patch implements an infrastructure for a new table driven scheme. This has several advantages: - Reduces the kernel size by approx 2kB. (The ARM instruction decoding will eventually have -3.1kB code, +1.3kB data; with similar or better estimated savings for Thumb decoding.) - Allows programmatic checking of decoding consistency and test case coverage. - Provides more uniform source code and is therefore, arguably, clearer. For a detailed explanation of how decoding tables work see the in-source documentation in kprobes.h, and also for kprobe_decode_insn(). Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Extend arch_specific_insn to add pointer to emulated instructionJon Medhurst
When we come to emulating Thumb instructions then, to interwork correctly, the code on in the instruction slot must be invoked with a function pointer which has the least significant bit set. Rather that set this by hand in every Thumb emulation function we will add a new field for this purpose to arch_specific_insn, called insn_fn. This also enables us to seamlessly share emulation functions between ARM and Thumb code. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Add hooks to override singlestep()Jon Medhurst
When a probe fires we must single-step the instruction which was replaced by a breakpoint. As the steps to do this vary between ARM and Thumb instructions we need a way to customise single-stepping. This is done by adding a new hook called insn_singlestep to arch_specific_insn which is initialised by the instruction decoding functions. These single-step hooks must update PC and call the instruction handler. For Thumb instructions an additional step of updating ITSTATE is needed. We do this after calling the handler because some handlers will need to test if they are running in an IT block. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Use conditional breakpoints for ARM probesJon Medhurst
Now we no longer trigger probes on conditional instructions when the condition is false, we can make use of conditional instructions as breakpoints in ARM code to avoid taking unnecessary exceptions. Note, we can't rely on not getting an exception when the condition check fails, as that is Implementation Defined on newer ARM architectures. We therefore still need to perform manual condition checks as well. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Don't trigger probes on conditional instructions when ↵Jon Medhurst
condition is false This patch changes the behavior of kprobes on ARM so that: Kprobes on conditional instructions don't trigger when the condition is false. For conditional branches, this means that they don't trigger in the branch not taken case. Rationale: When probes are placed onto conditionally executed instructions in a Thumb IT block, they may not fire if the condition is not met. This is because we use invalid instructions for breakpoints and "it is IMPLEMENTATION DEFINED whether the instruction executes as a NOP or causes an Undefined Instruction exception". Therefore, for consistency, we will ignore all probes on any conditional instructions when the condition is false. Alternative solutions seem to be too complex to implement or inconsistent. This issue was discussed on linux.arm.kernel in the thread titled "[RFC] kprobes with thumb2 conditional code" See http://comments.gmane.org/gmane.linux.linaro.devel/2985 Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Add it_advance()Jon Medhurst
This advances the ITSTATE bits in CPSR to their values for the next instruction. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Add condition code checking to Thumb emulationJon Medhurst
Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Add Thumb breakpoint supportJon Medhurst
Extend the breakpoint insertion and catching functions to support Thumb code. As breakpoints are no longer of a fixed size, the flush_insns macro is modified to take a size argument instead of an instruction count. Note, we need both 16- and 32-bit Thumb breakpoints, because if we were to use a 16-bit breakpoint to replace a 32-bit instruction which was in an IT block, and the condition check failed, then the breakpoint may not fire (it's unpredictable behaviour) and the CPU could then try and execute the second half of the 32-bit Thumb instruction. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Add Thumb instruction decoding stubsJon Medhurst
Extend arch_prepare_kprobe to support probing of Thumb code. For the actual decoding of Thumb instructions, stub functions are added which currently just reject the probe. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Make kprobes framework work on Thumb-2 kernelsJon Medhurst
Fix up kprobes framework so that it builds and correctly interworks on Thumb-2 kernels. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Make str_pc_offset a constant on ARMv7Jon Medhurst
The str_pc_offset value is architecturally defined on ARMv7 onwards so we can make it a compile time constant. This means on Thumb kernels the runtime checking code isn't needed, which saves us from having to fix it to work for Thumb. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Move find_str_pc_offset into kprobes-common.cJon Medhurst
Move str_pc_offset into kprobes-common.c as it will be needed by common code later. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Move is_writeback define to header file.Jon Medhurst
This will be used later in other files. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Add kprobes-common.cJon Medhurst
This file will contain the instruction decoding and emulation code which is common to both ARM and Thumb instruction sets. For now, we will just move over condition_checks from kprobes-arm.c This table is also renamed to kprobe_condition_checks to avoid polluting the public namespace with a too generic name. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Split out internal parts of kprobes.hJon Medhurst
Later, we will be adding a considerable amount of internal implementation definitions to kprobe header files and it would be good to have these in local header file along side the source code, rather than pollute the existing header which is include by all users of kprobes. To this end, we add arch/arm/kernel/kprobes.h and move into this the existing internal defintions from arch/arm/include/asm/kprobes.h Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: kprobes: Rename kprobes-decode.c to kprobes-arm.cJon Medhurst
This file contains decoding and emulation functions for the ARM instruction set. As we will later be adding a file for Thumb and a file with common decoding functions, this renaming makes things clearer. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: Thumb-2: Support Thumb-2 in undefined instruction handlerJon Medhurst
This patch allows undef_hook's to be specified for 32-bit Thumb instructions and also to be used for thumb kernel-side code. 32-bit Thumb instructions are specified in the form: ((first_half << 16 ) | second_half) which matches the layout used by the ARM ARM. ptrace was handling 32-bit Thumb instructions by hooking the first halfword and manually checking the second half. This method would be broken by this patch so it is migrated to make use of the new Thumb-2 support. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-13ARM: Thumb-2: Fix exception return sequence to restore stack correctlyJon Medhurst
The implementation of svc_exit didn't take into account any stack hole created by svc_entry; as happens with the undef handler when kprobes are configured. The fix is to read the saved value of SP rather than trying to calculate it. Signed-off-by: Jon Medhurst <tixy@yxit.co.uk> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
2011-07-12ARM: introduce handle_IRQ() not to dump exception stackRussell King - ARM Linux
On Mon, Jul 11, 2011 at 3:52 PM, Russell King - ARM Linux <linux@arm.linux.org.uk> wrote: ... > The __exception annotation on a function causes this to happen: > > [<c002406c>] (asm_do_IRQ+0x6c/0x8c) from [<c0024b84>] > (__irq_svc+0x44/0xcc) > Exception stack(0xc3897c78 to 0xc3897cc0) > 7c60: 4022d320 4022e000 > 7c80: 08000075 00001000 c32273c0 c03ce1c0 c2b49b78 4022d000 c2b420b4 00000001 > 7ca0: 00000000 c3897cfc 00000000 c3897cc0 c00afc54 c002edd8 00000013 ffffffff > > Where that stack dump represents the pt_regs for the exception which > happened. Any function found in while unwinding will cause this to > be printed. > > If you insert a C function between the IRQ assembly and asm_do_IRQ, > the > dump you get from asm_do_IRQ will be the stack for your function, > not > the pt_regs. That makes the feature useless. > When __irq_svc - or any of the other exception handling assembly code - calls the C code, the stack pointer will be pointing at the pt_regs structure. All the entry points into C code from the exception handling code are marked with __exception or __exception_irq_enter to indicate that they are one of the functions which has pt_regs above them. Normally, when you've entered asm_do_IRQ() you will have this stack layout (higher address towards top): pt_regs asm_do_IRQ frame If you insert a C function between the exception assembly code and asm_do_IRQ, you end up with this stack layout instead: pt_regs your function frame asm_do_IRQ frame This means when we unwind, we'll get to asm_do_IRQ, and rather than dumping out the pt_regs, we'll dump out your functions stack frame instead, because that's what is above the asm_do_IRQ stack frame rather than the expected pt_regs structure. The fix is to introduce handle_IRQ() for no exception stack dump, so it can be called with MULTI_IRQ_HANDLER is selected and a C function is between the assembly code and the actual IRQ handling code. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Eric Miao <eric.y.miao@gmail.com>
2011-07-09ARM: vfp: fix a hole in VFP thread migrationRussell King
Fix a hole in the VFP thread migration. Lets define two threads. Thread 1, we'll call 'interesting_thread' which is a thread which is running on CPU0, using VFP (so vfp_current_hw_state[0] = &interesting_thread->vfpstate) and gets migrated off to CPU1, where it continues execution of VFP instructions. Thread 2, we'll call 'new_cpu0_thread' which is the thread which takes over on CPU0. This has also been using VFP, and last used VFP on CPU0, but doesn't use it again. The following code will be executed twice: cpu = thread->cpu; /* * On SMP, if VFP is enabled, save the old state in * case the thread migrates to a different CPU. The * restoring is done lazily. */ if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu]) { vfp_save_state(vfp_current_hw_state[cpu], fpexc); vfp_current_hw_state[cpu]->hard.cpu = cpu; } /* * Thread migration, just force the reloading of the * state on the new CPU in case the VFP registers * contain stale data. */ if (thread->vfpstate.hard.cpu != cpu) vfp_current_hw_state[cpu] = NULL; The first execution will be on CPU0 to switch away from 'interesting_thread'. interesting_thread->cpu will be 0. So, vfp_current_hw_state[0] points at interesting_thread->vfpstate. The hardware state will be saved, along with the CPU number (0) that it was executing on. 'thread' will be 'new_cpu0_thread' with new_cpu0_thread->cpu = 0. Also, because it was executing on CPU0, new_cpu0_thread->vfpstate.hard.cpu = 0, and so the thread migration check is not triggered. This means that vfp_current_hw_state[0] remains pointing at interesting_thread. The second execution will be on CPU1 to switch _to_ 'interesting_thread'. So, 'thread' will be 'interesting_thread' and interesting_thread->cpu now will be 1. The previous thread executing on CPU1 is not relevant to this so we shall ignore that. We get to the thread migration check. Here, we discover that interesting_thread->vfpstate.hard.cpu = 0, yet interesting_thread->cpu is now 1, indicating thread migration. We set vfp_current_hw_state[1] to NULL. So, at this point vfp_current_hw_state[] contains the following: [0] = &interesting_thread->vfpstate [1] = NULL Our interesting thread now executes a VFP instruction, takes a fault which loads the state into the VFP hardware. Now, through the assembly we now have: [0] = &interesting_thread->vfpstate [1] = &interesting_thread->vfpstate CPU1 stops due to ptrace (and so saves its VFP state) using the thread switch code above), and CPU0 calls vfp_sync_hwstate(). if (vfp_current_hw_state[cpu] == &thread->vfpstate) { vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN); BANG, we corrupt interesting_thread's VFP state by overwriting the more up-to-date state saved by CPU1 with the old VFP state from CPU0. Fix this by ensuring that we have sane semantics for the various state describing variables: 1. vfp_current_hw_state[] points to the current owner of the context information stored in each CPUs hardware, or NULL if that state information is invalid. 2. thread->vfpstate.hard.cpu always contains the most recent CPU number which the state was loaded into or NR_CPUS if no CPU owns the state. So, for a particular CPU to be a valid owner of the VFP state for a particular thread t, two things must be true: vfp_current_hw_state[cpu] == &t->vfpstate && t->vfpstate.hard.cpu == cpu. and that is valid from the moment a CPU loads the saved VFP context into the hardware. This gives clear and consistent semantics to interpreting these variables. This patch also fixes thread copying, ensuring that t->vfpstate.hard.cpu is invalidated, otherwise CPU0 may believe it was the last owner. The hole can happen thus: - thread1 runs on CPU2 using VFP, migrates to CPU3, exits and thread_info freed. - New thread allocated from a previously running thread on CPU2, reusing memory for thread1 and copying vfp.hard.cpu. At this point, the following are true: new_thread1->vfpstate.hard.cpu == 2 &new_thread1->vfpstate == vfp_current_hw_state[2] Lastly, this also addresses thread flushing in a similar way to thread copying. Hole is: - thread runs on CPU0, using VFP, migrates to CPU1 but does not use VFP. - thread calls execve(), so thread flush happens, leaving vfp_current_hw_state[0] intact. This vfpstate is memset to 0 causing thread->vfpstate.hard.cpu = 0. - thread migrates back to CPU0 before using VFP. At this point, the following are true: thread->vfpstate.hard.cpu == 0 &thread->vfpstate == vfp_current_hw_state[0] Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-08Merge branch 'for-rmk' of git://linux-arm.org/linux-2.6-wd into devel-stableRussell King
2011-07-07ARM: vmlinux.lds: use _text and _stext the same way as x86Russell King
x86 uses _text to mark the start of the kernel image including the head text, and _stext to mark the start of the .text section. Change our vmlinux.lds to conform. An audit of the places which use _stext and _text in arch/arm indicates no users of either symbol are impacted by this change. It does mean a slight change to /proc/iomem output. Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org> Tested-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-07ARM: vmlinux.lds: move init sections between text and data sectionsRussell King
Place the init sections between the text and data sections. This means all code is grouped together at the beginning of the kernel image, and all data is at the end of the image. This avoids problems with the 24-bit branch instruction relocations becoming invalid with large initramfs images. Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org> Tested-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-07ARM: vmlinux.lds: remove .rodata/.rodata1 from main .text segmentRussell King
RODATA() already handles these sections, so allow it to take care of them for us. Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org> Tested-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-07ARM: vmlinux.lds: rearrange .init output sectionRussell King
Keep the various linker tables as separate output sections rather than combining them together into one big .init section. This makes the 'vmlinux' easier to see what is placed where. Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org> Tested-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-07ARM: vmlinux.lds: move discarded sections to beginningRussell King
Rather than scattering the discarded sections throughout the linker file, move them to the start. Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org> Tested-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-07ARM: perf: add support for the Cortex-A15 PMUWill Deacon
This patch adds support for the Cortex-A15 PMU to the ARMv7 perf-event backend. Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-07-07ARM: perf: add support for the Cortex-A5 PMUWill Deacon
This patch adds support for the Cortex-A5 PMU to the ARMv7 perf-event backend. Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-07-07ARM: perf: add PMUv2 common event definitionsWill Deacon
The PMUv2 specification reserves a number of event encodings for common events. This patch adds these events to the common event enumeration in preparation for PMUv2 cores, such as Cortex-A15. Acked-by: Jean Pihet <j-pihet@ti.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-07-07ARM: perf: remove confusing comment from v7 perf events backendWill Deacon
The comment about measuring TLB misses and refills in the ARMv7 perf backend makes little sense and refers loosely to raw counters that should be used instead. This patch removes the comments to avoid any confusion. Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-07-07ARM: hwcaps: add new HWCAP defines for ARMv7-AWill Deacon
Modern ARMv7-A cores can optionally implement these new hardware features: - VFPv4: The latest version of the ARMv7 vector floating-point extensions, including hardware support for fused multiple accumulate. D16 or D32 variants may be implemented. - Integer divide: The SDIV and UDIV instructions provide signed and unsigned integer division in hardware. When implemented, these instructions may be available in either both Thumb and ARM, or Thumb only. This patch adds new HWCAP defines to describe these new features. The integer divide capabilities are split into two bits for ARM and Thumb respectively. Whilst HWCAP_IDIVA should never be set if HWCAP_IDIVT is clear, separating the bits makes it easier to interpret from userspace. Signed-off-by: Will Deacon <will.deacon@arm.com>
2011-07-07ARM: 6994/1: smp_twd: Fix typo in 'twd_timer_rate' printingVitaly Kuzmichev
To get hundredths of MHz the rate needs to be divided by 10'000. Here is an example: twd_timer_rate = 123456789 Before the patch: twd_timer_rate / 1000000 = 123 (twd_timer_rate / 1000000) % 100 = 23 Result: 123.23MHz. After being fixed: twd_timer_rate / 1000000 = 123 (twd_timer_rate / 10000) % 100 = 45 Result: 123.45MHz. Signed-off-by: Vitaly Kuzmichev <vkuzmichev@mvista.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-07ARM: 6993/1: platsmp: Allow secondary cpu hotplug with maxcpus=1Stephen Boyd
If an ARM system has multiple cpus in the same socket and the kernel is booted with maxcpus=1, secondary cpus are possible but not present due to how platform_smp_prepare_cpus() is called. Since most typical ARM processors don't actually support physical hotplug, initialize the present map to be equal to the possible map in generic ARM SMP code. Also, always call platform_smp_prepare_cpus() as long as max_cpus is non-zero (0 means no SMP) to allow platform code to do any SMP setup. After applying this patch it's possible to boot an ARM system with maxcpus=1 on the command line and then hotplug in secondary cpus via sysfs. This is more in line with how x86 does things. Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Kukjin Kim <kgene.kim@samsung.com> Cc: David Brown <davidb@codeaurora.org> Cc: Tony Lindgren <tony@atomide.com> Cc: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com> Cc: Linus Walleij <linus.walleij@stericsson.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-06ARM: 6960/1: allow enabling SCU code on UPRob Herring
The scu_power_mode function can be used on UP builds as it drives signals to an SOC power controller. So make it selectable for !SMP. Signed-off-by: Rob Herring <rob.herring@calxeda.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-06ARM: 6985/1: export functions to determine the presence of I/DTCMLinus Walleij
By allowing code to detect whether DTCM or ITCM is present, code paths involving TCM can be avoided when running on platforms that lack it. This is good for creating single kernels across several archs, if some of them utilize TCM but others don't. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-06ARM: 6984/1: enhance TCM robustnessLinus Walleij
The PB11MPCore reports "3" DTCM banks, but anything above 2 is an "undefined" value, so push this to become 0. Further add some checks if code is compiled to TCM even if there is no D/ITCM present in the system, and if we can really fit the compiled code. We don't do the BUG() since it's not helpful, it's better to deal with non-present TCM dynamically. If there is nothing compiled to the TCM and no TCM is detected, it will now just shut up even if TCM support is enabled. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-05ARM: move memory layout sanity checking before meminfo initializationRussell King
Ensure that the meminfo array is sanity checked before we pass the memory to memblock. This helps to ensure that memblock and meminfo agree on the dimensions of memory, especially when more memory is passed than the kernel can deal with. Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-05ARM: 6989/1: perf: do not start the PMU when no events are presentWill Deacon
armpmu_enable can be called in situations where no events are present (for example, from the event rotation tick after a profiled task has exited). In this case, we currently start the PMU anyway which may leave it active inevitably without any events being monitored. This patch adds a simple check to the enabling code so that we avoid starting the PMU when no events are present. Cc: <stable@kernel.org> Reported-by: Ashwin Chaugle <ashwinc@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-02ARM: entry: no need to reload the SPSR value from struct pt_regsRussell King
The SVC IRQ, prefetch and data abort handlers preserve the SPSR value via r5 across the exception. Rather than re-loading it from pt_regs, use the preserved value instead. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-02ARM: entry: data abort: tail-call the main data abort handlerRussell King
Tail-call the main C data abort handler code from the per-CPU helper code. Update the comments in the code wrt the new calling and return register state. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2011-07-02ARM: entry: data abort: arrange for CPU abort helpers to take pc/psr in r4/r5Russell King
Re-jig the CPU abort helpers to take the PC/PSR in r4/r5 rather than r2/r3. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>