BMC/Intel-BMC/linux.git/arch/arc/include/asm/ptrace.h, branch dev

ARC: Make pt_regs regs unsigned

2015-08-05T06:18:21+00:00

KGDB fails to build after f51e2f191112 ("ARC: make sure instruction_pointer() returns unsigned value") The hack to force one specific reg to unsigned backfired. There's no reason to keep the regs signed after all. | CC arch/arc/kernel/kgdb.o |../arch/arc/kernel/kgdb.c: In function 'kgdb_trap': | ../arch/arc/kernel/kgdb.c:180:29: error: lvalue required as left operand of assignment | instruction_pointer(regs) -= BREAK_INSTR_SIZE; Reported-by: Yuriy Kolerov Fixes: f51e2f191112 ("ARC: make sure instruction_pointer() returns unsigned value") Cc: Alexey Brodkin Signed-off-by: Vineet Gupta

ARC: make sure instruction_pointer() returns unsigned value

2015-07-13T08:03:18+00:00

Currently instruction_pointer() returns pt_regs->ret and so return value is of type "long", which implicitly stands for "signed long". While that's perfectly fine when dealing with 32-bit values if return value of instruction_pointer() gets assigned to 64-bit variable sign extension may happen. And at least in one real use-case it happens already. In perf_prepare_sample() return value of perf_instruction_pointer() (which is an alias to instruction_pointer() in case of ARC) is assigned to (struct perf_sample_data)->ip (which type is "u64"). And what we see if instuction pointer points to user-space application that in case of ARC lays below 0x8000_0000 "ip" gets set properly with leading 32 zeros. But if instruction pointer points to kernel address space that starts from 0x8000_0000 then "ip" is set with 32 leadig "f"-s. I.e. id instruction_pointer() returns 0x8100_0000, "ip" will be assigned with 0xffff_ffff__8100_0000. Which is obviously wrong. In particular that issuse broke output of perf, because perf was unable to associate addresses like 0xffff_ffff__8100_0000 with anything from /proc/kallsyms. That's what we used to see: ----------->8---------- 6.27% ls [unknown] [k] 0xffffffff8046c5cc 2.96% ls libuClibc-0.9.34-git.so [.] memcpy 2.25% ls libuClibc-0.9.34-git.so [.] memset 1.66% ls [unknown] [k] 0xffffffff80666536 1.54% ls libuClibc-0.9.34-git.so [.] 0x000224d6 1.18% ls libuClibc-0.9.34-git.so [.] 0x00022472 ----------->8---------- With that change perf output looks much better now: ----------->8---------- 8.21% ls [kernel.kallsyms] [k] memset 3.52% ls libuClibc-0.9.34-git.so [.] memcpy 2.11% ls libuClibc-0.9.34-git.so [.] malloc 1.88% ls libuClibc-0.9.34-git.so [.] memset 1.64% ls [kernel.kallsyms] [k] _raw_spin_unlock_irqrestore 1.41% ls [kernel.kallsyms] [k] __d_lookup_rcu ----------->8---------- Signed-off-by: Alexey Brodkin Cc: arc-linux-dev@synopsys.com Cc: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Vineet Gupta

ARCv2: Support for ARCv2 ISA and HS38x cores

2015-06-22T08:36:55+00:00

The notable features are: - SMP configurations of upto 4 cores with coherency - Optional L2 Cache and IO-Coherency - Revised Interrupt Architecture (multiple priorites, reg banks, auto stack switch, auto regfile save/restore) - MMUv4 (PIPT dcache, Huge Pages) - Instructions for * 64bit load/store: LDD, STD * Hardware assisted divide/remainder: DIV, REM * Function prologue/epilogue: ENTER_S, LEAVE_S * IRQ enable/disable: CLRI, SETI * pop count: FFS, FLS * SETcc, BMSKN, XBFU... Signed-off-by: Vineet Gupta

ARC: Code cosmetics (Nothing semantical)

2013-08-29T12:21:15+00:00

* reduce editor lines taken by pt_regs * ARCompact ISA specific part of TLB Miss handlers clubbed together * cleanup some comments Signed-off-by: Vineet Gupta

ARC: pt_regs update #5: Use real ECR for pt_regs->event vs. synth values

2013-06-26T08:34:48+00:00

pt_regs->event was set with artificial values to identify the low level system event (syscall trap / breakpoint trap / exceptions / interrupts) With r8 saving out of the way, the full word can be used to save real ECR (Exception Cause Register) which helps idenify the event naturally, including additional info such as cause code, param. Only for Interrupts, where ECR is not applicable, do we resort to synthetic non ECR values. SAVE_ALL_TRAP/EXCEPTIONS can now be merged as they both use ECR with different runtime values. The ptrace helpers now use the sub-fields of ECR to distinguish the events (e.g. vector 0x25 is trap, param 0 is syscall...) The following benefits will follow: (1) This centralizes the location of where ECR is saved and will allow the cleanup of task->thread.cause_code ECR placeholder which is set in non-uniform way. Then ARC VM code can safely rely on it being there for purpose of finer grained VM_EXEC dcache flush (based on exec fault: I-TLB Miss) (2) Further, ECR being passed around from low level handlers as arg can be eliminated as it is part of standard reg-file in pt_regs Signed-off-by: Vineet Gupta

ARC: pt_regs update #4: r25 saved/restored unconditionally

2013-06-22T13:53:25+00:00

(This is a VERY IMP change for low level interrupt/exception handling) ----------------------------------------------------------------------- WHAT ----------------------------------------------------------------------- * User 25 now saved in pt_regs->user_r25 (vs. tsk->thread_info.user_r25) * This allows Low level interrupt code to unconditionally save r25 (vs. the prev version which would only do it for U->K transition). Ofcourse for nested interrupts, only the pt_regs->user_r25 of bottom-most frame is useful. * simplifies the interrupt prologue/epilogue * Needed for ARCv2 ISA code and done here to keep design similar with ARCompact event handling ----------------------------------------------------------------------- WHY ------------------------------------------------------------------------- With CONFIG_ARC_CURR_IN_REG, r25 is used to cache "current" task pointer in kernel mode. So when entering kernel mode from User Mode - user r25 is specially safe-kept (it being a callee reg is NOT part of pt_regs which are saved by default on each interrupt/trap/exception) - r25 loaded with current task pointer. Further, if interrupt was taken in kernel mode, this is skipped since we know that r25 already has valid "current" pointer. With 2 level of interrupts in ARCompact ISA, detecting this is difficult but still possible, since we could be in kernel mode but r25 not already saved (in fact the stack itself might not have been switched). A. User mode B. L1 IRQ taken C. L2 IRQ taken (while on 1st line of L1 ISR) So in #C, although in kernel mode, r25 not saved (infact SP not switched at all) Given that ARcompact has manual stack switching, we could use a bit of trickey - The low level code would make sure that SP is only set to kernel mode value at the very end (after saving r25). So a non kernel mode SP, even if in kernel mode, meant r25 was NOT saved. The same paradigm won't work in ARCv2 ISA since SP is auto-switched so it's setting can't be delayed/constrained. Signed-off-by: Vineet Gupta

ARC: pt_regs update #3: Remove unused gutter at start of callee_regs

2013-06-22T13:53:22+00:00

This is trickier than prev two: * context switching code saves kernel mode callee regs in the format of struct callee_regs thus needs adjustment. This also reduces the height of topmost kernel stack frame by 1 word. * Since kernel stack unwinder is sensitive to height of topmost kernel stack frame, that needs a word of adjustment too. ptrace needs a bit of updating since pt_regs now diverges from user_regs_struct. Signed-off-by: Vineet Gupta

ARC: pt_regs update #2: Remove unused gutter at start of pt_regs

2013-06-22T13:53:22+00:00

Signed-off-by: Vineet Gupta

ARC: pt_regs update #1: Align pt_regs end with end of kernel stack page

2013-06-22T13:53:21+00:00

Historically, pt_regs would end at offset of 1 word from end of stack page. ----------------- -> START of page (task->stack) | | | thread_info | ----------------- | | ^ ~ ~ | ~ ~ | | | | | | <---- pt_regs used to END here ----------------- | 1 word GUTTER | ----------------- -> End of page (START of kernel stack) This required special "one-off" considerations in low level code. The root cause is very likely assumption of "empty" SP by the original ARC kernel hackers, despite ARC700 always been "full" SP. So finally RIP one word gutter ! Signed-off-by: Vineet Gupta

ARC: Fix the typo in event identifier flags used by ptrace

2013-03-20T13:15:45+00:00

orig_r8_IS_EXCPN and orig_r8_IS_BRKPT were same values due to a copy/paste error. Although it looks bad and is wrong, it really doesn't affect gdb working. orig_r8_IS_BRKPT is the one relevant to debugging (breakpoints), since it is used to provide EFA vs. ERET to a ptrace "stop_pc" request. So when gdb has inserted a breakpoint, orig_r8_IS_BRKPT is already set, and anything else (i.e. orig_r8_IS_EXCPN) becoming same as it, really doesn't hurt gdb. The corollary case, could be nasty but nobody uses the ptrace "stop_pc" request in that case Signed-off-by: Vineet Gupta