Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751349AbbKYR3H (ORCPT ); Wed, 25 Nov 2015 12:29:07 -0500 Received: from verein.lst.de ([213.95.11.211]:60689 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750735AbbKYR24 (ORCPT ); Wed, 25 Nov 2015 12:28:56 -0500 In-Reply-To: <20151125172608.9588569260@newverein.lst.de> References: <20151125172608.9588569260@newverein.lst.de> From: Torsten Duwe Date: Wed, 25 Nov 2015 17:23:32 +0100 Subject: [PATCH v4 1/9] ppc64 (le): prepare for -mprofile-kernel To: Steven Rostedt , Michael Ellerman Cc: Jiri Kosina , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, live-patching@vger.kernel.org Message-Id: <20151125172855.49E3469260@newverein.lst.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4465 Lines: 153 The gcc switch -mprofile-kernel, available for ppc64 on gcc > 4.8.5, allows to call _mcount very early in the function, which low-level ASM code and code patching functions need to consider. Especially the link register and the parameter registers are still alive and not yet saved into a new stack frame. Signed-off-by: Torsten Duwe --- arch/powerpc/kernel/entry_64.S | 44 +++++++++++++++++++++++++++++++++++++++-- arch/powerpc/kernel/ftrace.c | 12 +++++++++-- arch/powerpc/kernel/module_64.c | 13 ++++++++++++ 3 files changed, 65 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index a94f155..8d56b16 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -1206,7 +1206,11 @@ _GLOBAL(enter_prom) #ifdef CONFIG_DYNAMIC_FTRACE _GLOBAL(mcount) _GLOBAL(_mcount) - blr + mflr r0 + mtctr r0 + ld r0,LRSAVE(r1) + mtlr r0 + bctr _GLOBAL_TOC(ftrace_caller) /* Taken from output of objdump from lib64/glibc */ @@ -1262,13 +1266,28 @@ _GLOBAL(ftrace_stub) #ifdef CONFIG_FUNCTION_GRAPH_TRACER _GLOBAL(ftrace_graph_caller) +#ifdef CC_USING_MPROFILE_KERNEL + // with -mprofile-kernel, parameter regs are still alive at _mcount + std r10, 104(r1) + std r9, 96(r1) + std r8, 88(r1) + std r7, 80(r1) + std r6, 72(r1) + std r5, 64(r1) + std r4, 56(r1) + std r3, 48(r1) + mfctr r4 // ftrace_caller has moved local addr here + std r4, 40(r1) + mflr r3 // ftrace_caller has restored LR from stack +#else /* load r4 with local address */ ld r4, 128(r1) - subi r4, r4, MCOUNT_INSN_SIZE /* Grab the LR out of the caller stack frame */ ld r11, 112(r1) ld r3, 16(r11) +#endif + subi r4, r4, MCOUNT_INSN_SIZE bl prepare_ftrace_return nop @@ -1277,6 +1296,26 @@ _GLOBAL(ftrace_graph_caller) * prepare_ftrace_return gives us the address we divert to. * Change the LR in the callers stack frame to this. */ + +#ifdef CC_USING_MPROFILE_KERNEL + mtlr r3 + + ld r0, 40(r1) + mtctr r0 + ld r10, 104(r1) + ld r9, 96(r1) + ld r8, 88(r1) + ld r7, 80(r1) + ld r6, 72(r1) + ld r5, 64(r1) + ld r4, 56(r1) + ld r3, 48(r1) + + addi r1, r1, 112 + mflr r0 + std r0, LRSAVE(r1) + bctr +#else ld r11, 112(r1) std r3, 16(r11) @@ -1284,6 +1323,7 @@ _GLOBAL(ftrace_graph_caller) mtlr r0 addi r1, r1, 112 blr +#endif _GLOBAL(return_to_handler) /* need to save return values */ diff --git a/arch/powerpc/kernel/ftrace.c b/arch/powerpc/kernel/ftrace.c index 44d4d8e..080c525 100644 --- a/arch/powerpc/kernel/ftrace.c +++ b/arch/powerpc/kernel/ftrace.c @@ -306,11 +306,19 @@ __ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) * The load offset is different depending on the ABI. For simplicity * just mask it out when doing the compare. */ +#ifndef CC_USING_MPROFILE_KERNEL if ((op[0] != 0x48000008) || ((op[1] & 0xffff0000) != 0xe8410000)) { - pr_err("Unexpected call sequence: %x %x\n", op[0], op[1]); + pr_err("Unexpected call sequence at %p: %x %x\n", + ip, op[0], op[1]); return -EINVAL; } - +#else + /* look for patched "NOP" on ppc64 with -mprofile-kernel */ + if (op[0] != 0x60000000) { + pr_err("Unexpected call at %p: %x\n", ip, op[0]); + return -EINVAL; + } +#endif /* If we never set up a trampoline to ftrace_caller, then bail */ if (!rec->arch.mod->arch.tramp) { pr_err("No ftrace trampoline\n"); diff --git a/arch/powerpc/kernel/module_64.c b/arch/powerpc/kernel/module_64.c index 6838451..0819ce7 100644 --- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -475,6 +475,19 @@ static unsigned long stub_for_addr(Elf64_Shdr *sechdrs, static int restore_r2(u32 *instruction, struct module *me) { if (*instruction != PPC_INST_NOP) { +#ifdef CC_USING_MPROFILE_KERNEL + /* -mprofile_kernel sequence starting with + * mflr r0; std r0, LRSAVE(r1) + */ + if (instruction[-3] == 0x7c0802a6 && + instruction[-2] == 0xf8010010) { + /* Nothing to be done here, it's an _mcount + * call location and r2 will have to be + * restored in the _mcount function. + */ + return 2; + }; +#endif pr_err("%s: Expect noop after relocate, got %08x\n", me->name, *instruction); return 0; -- 1.8.5.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/