From patchwork Thu Jun 20 18:54:10 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Naveen N Rao X-Patchwork-Id: 13706258 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A01F61AD48B; Thu, 20 Jun 2024 18:57:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718909871; cv=none; b=YATjjkSKXyj/qXYs98ElUQ3vkVUwqw4Ez04FfzyVttiUUbE7qsU5HIUoG5NpkHC4OBjZyEVIe8Ip3rlF4KB+Co66aNlUyjSDBiOfq2MI0S3I0yHbY6naLn08h0a3T3tE69hc9N2vIyFIfQyZS70mLHbw7wt8kFi76PbV4MP8zeg= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718909871; c=relaxed/simple; bh=985gdIH0ppfk83Q1NEtcSEVKXPnJFOVze98CIIKBeis=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JsAH8+wFHIumOMpbUbHcBndAlXBYRZuxpXOsoYeIoLOfmK3cAMCUp5lLXhrc98ejZ2osuCvCpBbI3jKFEqoWOqbjNdqaV+lqLqtpsdqb2qoK9bY4Nqr/p0jWaZp/SXuoXWYBB/fsAX9gat9xy418iokP3GTXxFwjJuyNxYZ+9SQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=trVR0iu4; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="trVR0iu4" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0C620C2BD10; Thu, 20 Jun 2024 18:57:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1718909871; bh=985gdIH0ppfk83Q1NEtcSEVKXPnJFOVze98CIIKBeis=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=trVR0iu4hhVM57E5fuyGCzfbfCcOnY7aDX9RcPkymF8umOX9AcQFCXIjo4wd9Ni4Z YmaasVehz/3SNtDbjiE1qSP3VLb1Rsw9abX6cQ2nxcswmPH209c0z+/6MmJVFRVL5Z yL+wq+Z8hPIM+nlEGkfjGTRnZxqlXa5hdBo4feqXe22u0A8AhHdD15M3Deft8T6pmu 0qXDenCxEpwuzNo0P3+psCok+RWbVHQLjFOOpwUMovG9ZQ42Xt1KxL2hP2JdGv/Ak5 J9xnemYOyRo+ntSTpb8j9997fV4g/ersPcOcGWEcPKYkpkkzGrCUY0mfrSSL1AXg4J XPv+BEtjk1M7g== From: Naveen N Rao To: , , Cc: Michael Ellerman , Steven Rostedt , Masami Hiramatsu , Nicholas Piggin , Christophe Leroy , Masahiro Yamada , Mark Rutland , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Song Liu , Jiri Olsa Subject: [RFC PATCH v3 07/11] powerpc/ftrace: Add support for DYNAMIC_FTRACE_WITH_CALL_OPS Date: Fri, 21 Jun 2024 00:24:10 +0530 Message-ID: X-Mailer: git-send-email 2.45.2 In-Reply-To: References: Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-State: RFC Implement support for DYNAMIC_FTRACE_WITH_CALL_OPS similar to the arm64 implementation. This works by patching-in a pointer to an associated ftrace_ops structure before each traceable function. If multiple ftrace_ops are associated with a call site, then a special ftrace_list_ops is used to enable iterating over all the registered ftrace_ops. If no ftrace_ops are associated with a call site, then a special ftrace_nop_ops structure is used to render the ftrace call as a no-op. ftrace trampoline can then read the associated ftrace_ops for a call site by loading from an offset from the LR, and branch directly to the associated function. The primary advantage with this approach is that we don't have to iterate over all the registered ftrace_ops for call sites that have a single ftrace_ops registered. This is the equivalent of implementing support for dynamic ftrace trampolines, which set up a special ftrace trampoline for each registered ftrace_ops and have individual call sites branch into those directly. A secondary advantage is that this gives us a way to add support for direct ftrace callers without having to resort to using stubs. The address of the direct call trampoline can be loaded from the ftrace_ops structure. To support this, we reserve a nop before each function on 32-bit powerpc. For 64-bit powerpc, two nops are reserved before each out-of-line stub. During ftrace activation, we update this location with the associated ftrace_ops pointer. Then, on ftrace entry, we load from this location and call into ftrace_ops->func(). For 64-bit powerpc, we ensure that the out-of-line stub area is doubleword aligned so that ftrace_ops address can be updated atomically. Signed-off-by: Naveen N Rao --- arch/powerpc/Kconfig | 1 + arch/powerpc/Makefile | 4 ++ arch/powerpc/include/asm/ftrace.h | 5 +- arch/powerpc/kernel/asm-offsets.c | 4 ++ arch/powerpc/kernel/trace/ftrace.c | 59 +++++++++++++++++++++- arch/powerpc/kernel/trace/ftrace_entry.S | 34 ++++++++++--- arch/powerpc/tools/gen-ftrace-pfe-stubs.sh | 5 +- 7 files changed, 101 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index dd7efca2275a..fde64ad19de5 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -235,6 +235,7 @@ config PPC select HAVE_DEBUG_STACKOVERFLOW select HAVE_DYNAMIC_FTRACE select HAVE_DYNAMIC_FTRACE_WITH_ARGS if ARCH_USING_PATCHABLE_FUNCTION_ENTRY || MPROFILE_KERNEL || PPC32 + select HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS if FTRACE_PFE_OUT_OF_LINE || (PPC32 && ARCH_USING_PATCHABLE_FUNCTION_ENTRY) select HAVE_DYNAMIC_FTRACE_WITH_REGS if ARCH_USING_PATCHABLE_FUNCTION_ENTRY || MPROFILE_KERNEL || PPC32 select HAVE_EBPF_JIT select HAVE_EFFICIENT_UNALIGNED_ACCESS diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index bb920d48ec6e..c3e577dea137 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -158,8 +158,12 @@ KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY ifdef CONFIG_FTRACE_PFE_OUT_OF_LINE CC_FLAGS_FTRACE := -fpatchable-function-entry=1 else +ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS # PPC32 only +CC_FLAGS_FTRACE := -fpatchable-function-entry=3,1 +else CC_FLAGS_FTRACE := -fpatchable-function-entry=2 endif +endif else CC_FLAGS_FTRACE := -pg ifdef CONFIG_MPROFILE_KERNEL diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index 9da1da0f87b4..938cecf72eb1 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -137,8 +137,11 @@ static inline u8 this_cpu_get_ftrace_enabled(void) { return 1; } extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[]; #ifdef CONFIG_FTRACE_PFE_OUT_OF_LINE struct ftrace_pfe_stub { +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS + struct ftrace_ops *ftrace_op; +#endif u32 insn[4]; -}; +} __aligned(sizeof(unsigned long)); extern struct ftrace_pfe_stub ftrace_pfe_stub_text[], ftrace_pfe_stub_inittext[]; extern unsigned long ftrace_pfe_stub_text_count, ftrace_pfe_stub_inittext_count; #endif diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 5f1a411d714c..a11ea5f4d86a 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -678,5 +678,9 @@ int main(void) DEFINE(FTRACE_PFE_STUB_SIZE, sizeof(struct ftrace_pfe_stub)); #endif +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS + OFFSET(FTRACE_OPS_FUNC, ftrace_ops, func); +#endif + return 0; } diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index 9f3c10307331..028548312c23 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -38,8 +38,11 @@ unsigned long ftrace_call_adjust(unsigned long addr) return 0; if (IS_ENABLED(CONFIG_ARCH_USING_PATCHABLE_FUNCTION_ENTRY) && - !IS_ENABLED(CONFIG_FTRACE_PFE_OUT_OF_LINE)) + !IS_ENABLED(CONFIG_FTRACE_PFE_OUT_OF_LINE)) { addr += MCOUNT_INSN_SIZE; + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS)) + addr += MCOUNT_INSN_SIZE; + } return addr; } @@ -241,6 +244,46 @@ static int ftrace_init_pfe_stub(struct module *mod, struct dyn_ftrace *rec) #endif } +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS +static const struct ftrace_ops *powerpc_rec_get_ops(struct dyn_ftrace *rec) +{ + const struct ftrace_ops *ops = NULL; + + if (rec->flags & FTRACE_FL_CALL_OPS_EN) { + ops = ftrace_find_unique_ops(rec); + WARN_ON_ONCE(!ops); + } + + if (!ops) + ops = &ftrace_list_ops; + + return ops; +} + +static int ftrace_rec_set_ops(struct dyn_ftrace *rec, const struct ftrace_ops *ops) +{ + if (IS_ENABLED(CONFIG_FTRACE_PFE_OUT_OF_LINE)) + return patch_ulong((void *)(ftrace_get_pfe_stub(rec) - sizeof(unsigned long)), + (unsigned long)ops); + else + return patch_ulong((void *)(rec->ip - MCOUNT_INSN_SIZE - sizeof(unsigned long)), + (unsigned long)ops); +} + +static int ftrace_rec_set_nop_ops(struct dyn_ftrace *rec) +{ + return ftrace_rec_set_ops(rec, &ftrace_nop_ops); +} + +static int ftrace_rec_update_ops(struct dyn_ftrace *rec) +{ + return ftrace_rec_set_ops(rec, powerpc_rec_get_ops(rec)); +} +#else +static int ftrace_rec_set_nop_ops(struct dyn_ftrace *rec) { return 0; } +static int ftrace_rec_update_ops(struct dyn_ftrace *rec) { return 0; } +#endif + #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr) { @@ -271,6 +314,10 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) if (!ret) ret = ftrace_modify_code(ip, old, new); + ret = ftrace_rec_update_ops(rec); + if (ret) + return ret; + if (!ret && IS_ENABLED(CONFIG_FTRACE_PFE_OUT_OF_LINE)) ret = ftrace_modify_code(rec->ip, ppc_inst(PPC_RAW_NOP()), ppc_inst(PPC_RAW_BRANCH((long)ftrace_get_pfe_stub(rec) - (long)rec->ip))); @@ -322,16 +369,19 @@ void ftrace_replace_code(int enable) case FTRACE_UPDATE_MODIFY_CALL: ret = ftrace_get_call_inst(rec, new_addr, &new_call_inst); ret |= ftrace_get_call_inst(rec, addr, &call_inst); + ret |= ftrace_rec_update_ops(rec); old = call_inst; new = new_call_inst; break; case FTRACE_UPDATE_MAKE_NOP: ret = ftrace_get_call_inst(rec, addr, &call_inst); + ret |= ftrace_rec_set_nop_ops(rec); old = call_inst; new = nop_inst; break; case FTRACE_UPDATE_MAKE_CALL: ret = ftrace_get_call_inst(rec, new_addr, &call_inst); + ret |= ftrace_rec_update_ops(rec); old = nop_inst; new = call_inst; break; @@ -443,6 +493,13 @@ int ftrace_update_ftrace_func(ftrace_func_t func) ppc_inst_t old, new; int ret; + /* + * When using CALL_OPS, the function to call is associated with the + * call site, and we don't have a global function pointer to update. + */ + if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS)) + return 0; + old = ppc_inst_read((u32 *)&ftrace_call); new = ftrace_create_branch_inst(ip, ppc_function_entry(func), 1); ret = ftrace_modify_code(ip, old, new); diff --git a/arch/powerpc/kernel/trace/ftrace_entry.S b/arch/powerpc/kernel/trace/ftrace_entry.S index b1cbef24f18f..a76aedd970a6 100644 --- a/arch/powerpc/kernel/trace/ftrace_entry.S +++ b/arch/powerpc/kernel/trace/ftrace_entry.S @@ -85,11 +85,21 @@ /* Save callee's TOC in the ABI compliant location */ std r2, STK_GOT(r1) LOAD_PACA_TOC() /* get kernel TOC in r2 */ +#endif + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS + /* r7 points to the instruction following the call to ftrace */ + PPC_LL r5, -(MCOUNT_INSN_SIZE*2 + SZL)(r7) + PPC_LL r12, FTRACE_OPS_FUNC(r5) + mtctr r12 +#else /* !CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS */ +#ifdef CONFIG_PPC64 LOAD_REG_ADDR(r3, function_trace_op) ld r5,0(r3) #else lis r3,function_trace_op@ha lwz r5,function_trace_op@l(r3) +#endif #endif /* Save special regs */ @@ -196,20 +206,30 @@ #endif .endm -_GLOBAL(ftrace_regs_caller) - ftrace_regs_entry 1 - /* ftrace_call(r3, r4, r5, r6) */ +.macro ftrace_regs_func allregs +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_CALL_OPS + bctrl +#else + .if \allregs == 1 .globl ftrace_regs_call ftrace_regs_call: + .else +.globl ftrace_call +ftrace_call: + .endif + /* ftrace_call(r3, r4, r5, r6) */ bl ftrace_stub +#endif +.endm + +_GLOBAL(ftrace_regs_caller) + ftrace_regs_entry 1 + ftrace_regs_func 1 ftrace_regs_exit 1 _GLOBAL(ftrace_caller) ftrace_regs_entry 0 - /* ftrace_call(r3, r4, r5, r6) */ -.globl ftrace_call -ftrace_call: - bl ftrace_stub + ftrace_regs_func 0 ftrace_regs_exit 0 _GLOBAL(ftrace_stub) diff --git a/arch/powerpc/tools/gen-ftrace-pfe-stubs.sh b/arch/powerpc/tools/gen-ftrace-pfe-stubs.sh index ec95e99aff14..f23d3f74e029 100755 --- a/arch/powerpc/tools/gen-ftrace-pfe-stubs.sh +++ b/arch/powerpc/tools/gen-ftrace-pfe-stubs.sh @@ -24,12 +24,13 @@ num_pfe_stubs_inittext=$(${CROSS_COMPILE}objdump -r -j __patchable_function_entr cat > ${arch_vmlinux_S} < +#include #include .pushsection .tramp.ftrace.text,"aw" SYM_DATA(ftrace_pfe_stub_text_count, .long ${num_pfe_stubs_text}) -SYM_CODE_START(ftrace_pfe_stub_text) +SYM_START(ftrace_pfe_stub_text, SYM_L_GLOBAL, .balign SZL) .space ${num_pfe_stubs_text} * FTRACE_PFE_STUB_SIZE SYM_CODE_END(ftrace_pfe_stub_text) .popsection @@ -37,7 +38,7 @@ SYM_CODE_END(ftrace_pfe_stub_text) .pushsection .tramp.ftrace.init,"aw" SYM_DATA(ftrace_pfe_stub_inittext_count, .long ${num_pfe_stubs_inittext}) -SYM_CODE_START(ftrace_pfe_stub_inittext) +SYM_START(ftrace_pfe_stub_inittext, SYM_L_GLOBAL, .balign SZL) .space ${num_pfe_stubs_inittext} * FTRACE_PFE_STUB_SIZE SYM_CODE_END(ftrace_pfe_stub_inittext) .popsection