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Rao" , Mark Rutland , Daniel Borkmann , Masahiro Yamada , Nicholas Piggin , Alexei Starovoitov , Steven Rostedt , Andrii Nakryiko , Christophe Leroy , Vishal Chourasia , Mahesh J Salgaonkar , Masami Hiramatsu Subject: [PATCH v5 13/17] powerpc64/ftrace: Support .text larger than 32MB with out-of-line stubs Date: Mon, 16 Sep 2024 02:26:44 +0530 Message-ID: <20240915205648.830121-14-hbathini@linux.ibm.com> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240915205648.830121-1-hbathini@linux.ibm.com> References: <20240915205648.830121-1-hbathini@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: 7prbGMIuTuZTtK-rpyOA5amn9nEaKQPw X-Proofpoint-GUID: pJrYxvy1Zou96vUV_Ztis4oL2XfiaExX X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.680,FMLib:17.12.60.29 definitions=2024-09-15_12,2024-09-13_02,2024-09-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 mlxlogscore=999 adultscore=0 phishscore=0 spamscore=0 lowpriorityscore=0 clxscore=1015 bulkscore=0 suspectscore=0 mlxscore=0 impostorscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2408220000 definitions=main-2409150159 From: Naveen N Rao We are restricted to a .text size of ~32MB when using out-of-line function profile sequence. Allow this to be extended up to the previous limit of ~64MB by reserving space in the middle of .text. A new config option CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE is introduced to specify the number of function stubs that are reserved in .text. On boot, ftrace utilizes stubs from this area first before using the stub area at the end of .text. A ppc64le defconfig has ~44k functions that can be traced. A more conservative value of 32k functions is chosen as the default value of PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE so that we do not allot more space than necessary by default. If building a kernel that only has 32k trace-able functions, we won't allot any more space at the end of .text during the pass on vmlinux.o. Otherwise, only the remaining functions get space for stubs at the end of .text. This default value should help cover a .text size of ~48MB in total (including space reserved at the end of .text which can cover up to 32MB), which should be sufficient for most common builds. For a very small kernel build, this can be set to 0. Or, this can be bumped up to a larger value to support vmlinux .text size up to ~64MB. Signed-off-by: Naveen N Rao Signed-off-by: Hari Bathini --- Changes in v5: * num_ool_stubs_text_end used for setting up ftrace_ool_stub_text_end set to zero instead of computing to some random negative value when not required. arch/powerpc/Kconfig | 12 ++++++++++++ arch/powerpc/include/asm/ftrace.h | 6 ++++-- arch/powerpc/kernel/trace/ftrace.c | 21 +++++++++++++++++---- arch/powerpc/kernel/trace/ftrace_entry.S | 8 ++++++++ arch/powerpc/tools/Makefile | 2 +- arch/powerpc/tools/ftrace-gen-ool-stubs.sh | 16 ++++++++++++---- 6 files changed, 54 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index bae96b65f295..a0ce00368bab 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -573,6 +573,18 @@ config PPC_FTRACE_OUT_OF_LINE depends on PPC64 select ARCH_WANTS_PRE_LINK_VMLINUX +config PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE + int "Number of ftrace out-of-line stubs to reserve within .text" + default 32768 if PPC_FTRACE_OUT_OF_LINE + default 0 + help + Number of stubs to reserve for use by ftrace. This space is + reserved within .text, and is distinct from any additional space + added at the end of .text before the final vmlinux link. Set to + zero to have stubs only be generated at the end of vmlinux (only + if the size of vmlinux is less than 32MB). Set to a higher value + if building vmlinux larger than 48MB. + config HOTPLUG_CPU bool "Support for enabling/disabling CPUs" depends on SMP && (PPC_PSERIES || \ diff --git a/arch/powerpc/include/asm/ftrace.h b/arch/powerpc/include/asm/ftrace.h index bdbafc668b20..28f3590ca780 100644 --- a/arch/powerpc/include/asm/ftrace.h +++ b/arch/powerpc/include/asm/ftrace.h @@ -138,8 +138,10 @@ extern unsigned int ftrace_tramp_text[], ftrace_tramp_init[]; struct ftrace_ool_stub { u32 insn[4]; }; -extern struct ftrace_ool_stub ftrace_ool_stub_text_end[], ftrace_ool_stub_inittext[]; -extern unsigned int ftrace_ool_stub_text_end_count, ftrace_ool_stub_inittext_count; +extern struct ftrace_ool_stub ftrace_ool_stub_text_end[], ftrace_ool_stub_text[], + ftrace_ool_stub_inittext[]; +extern unsigned int ftrace_ool_stub_text_end_count, ftrace_ool_stub_text_count, + ftrace_ool_stub_inittext_count; #endif void ftrace_free_init_tramp(void); unsigned long ftrace_call_adjust(unsigned long addr); diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index 1fee074388cc..bee2c54a8c04 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -168,7 +168,7 @@ static int ftrace_get_call_inst(struct dyn_ftrace *rec, unsigned long addr, ppc_ static int ftrace_init_ool_stub(struct module *mod, struct dyn_ftrace *rec) { #ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE - static int ool_stub_text_end_index, ool_stub_inittext_index; + static int ool_stub_text_index, ool_stub_text_end_index, ool_stub_inittext_index; int ret = 0, ool_stub_count, *ool_stub_index; ppc_inst_t inst; /* @@ -191,9 +191,22 @@ static int ftrace_init_ool_stub(struct module *mod, struct dyn_ftrace *rec) ool_stub_index = &ool_stub_inittext_index; ool_stub_count = ftrace_ool_stub_inittext_count; } else if (is_kernel_text(rec->ip)) { - ool_stub = ftrace_ool_stub_text_end; - ool_stub_index = &ool_stub_text_end_index; - ool_stub_count = ftrace_ool_stub_text_end_count; + /* + * ftrace records are sorted, so we first use up the stub area within .text + * (ftrace_ool_stub_text) before using the area at the end of .text + * (ftrace_ool_stub_text_end), unless the stub is out of range of the record. + */ + if (ool_stub_text_index >= ftrace_ool_stub_text_count || + !is_offset_in_branch_range((long)rec->ip - + (long)&ftrace_ool_stub_text[ool_stub_text_index])) { + ool_stub = ftrace_ool_stub_text_end; + ool_stub_index = &ool_stub_text_end_index; + ool_stub_count = ftrace_ool_stub_text_end_count; + } else { + ool_stub = ftrace_ool_stub_text; + ool_stub_index = &ool_stub_text_index; + ool_stub_count = ftrace_ool_stub_text_count; + } #ifdef CONFIG_MODULES } else if (mod) { ool_stub = mod->arch.ool_stubs; diff --git a/arch/powerpc/kernel/trace/ftrace_entry.S b/arch/powerpc/kernel/trace/ftrace_entry.S index 5b2fc6483dce..a6bf7f841040 100644 --- a/arch/powerpc/kernel/trace/ftrace_entry.S +++ b/arch/powerpc/kernel/trace/ftrace_entry.S @@ -374,6 +374,14 @@ _GLOBAL(return_to_handler) blr #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ +#ifdef CONFIG_PPC_FTRACE_OUT_OF_LINE +SYM_DATA(ftrace_ool_stub_text_count, .long CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE) + +SYM_CODE_START(ftrace_ool_stub_text) + .space CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE * FTRACE_OOL_STUB_SIZE +SYM_CODE_END(ftrace_ool_stub_text) +#endif + .pushsection ".tramp.ftrace.text","aw",@progbits; .globl ftrace_tramp_text ftrace_tramp_text: diff --git a/arch/powerpc/tools/Makefile b/arch/powerpc/tools/Makefile index 3a389526498e..9eeb6edf02fe 100644 --- a/arch/powerpc/tools/Makefile +++ b/arch/powerpc/tools/Makefile @@ -1,7 +1,7 @@ # SPDX-License-Identifier: GPL-2.0-or-later quiet_cmd_gen_ftrace_ool_stubs = GEN $@ - cmd_gen_ftrace_ool_stubs = $< vmlinux.o $@ + cmd_gen_ftrace_ool_stubs = $< $(CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE) vmlinux.o $@ $(obj)/.vmlinux.arch.S: $(src)/ftrace-gen-ool-stubs.sh vmlinux.o FORCE $(call if_changed,gen_ftrace_ool_stubs) diff --git a/arch/powerpc/tools/ftrace-gen-ool-stubs.sh b/arch/powerpc/tools/ftrace-gen-ool-stubs.sh index 8e0a6d4ea202..d6bd834e0868 100755 --- a/arch/powerpc/tools/ftrace-gen-ool-stubs.sh +++ b/arch/powerpc/tools/ftrace-gen-ool-stubs.sh @@ -8,8 +8,9 @@ is_enabled() { grep -q "^$1=y" include/config/auto.conf } -vmlinux_o=${1} -arch_vmlinux_S=${2} +vmlinux_o=${2} +arch_vmlinux_S=${3} +arch_vmlinux_o=$(dirname ${arch_vmlinux_S})/$(basename ${arch_vmlinux_S} .S).o RELOCATION=R_PPC64_ADDR64 if is_enabled CONFIG_PPC32; then @@ -21,15 +22,22 @@ num_ool_stubs_text=$(${CROSS_COMPILE}objdump -r -j __patchable_function_entries num_ool_stubs_inittext=$(${CROSS_COMPILE}objdump -r -j __patchable_function_entries ${vmlinux_o} | grep ".init.text" | grep "${RELOCATION}" | wc -l) +num_ool_stubs_text_builtin=${1} +if [ ${num_ool_stubs_text} -gt ${num_ool_stubs_text_builtin} ]; then + num_ool_stubs_text_end=$(expr ${num_ool_stubs_text} - ${num_ool_stubs_text_builtin}) +else + num_ool_stubs_text_end=0 +fi + cat > ${arch_vmlinux_S} < #include .pushsection .tramp.ftrace.text,"aw" -SYM_DATA(ftrace_ool_stub_text_end_count, .long ${num_ool_stubs_text}) +SYM_DATA(ftrace_ool_stub_text_end_count, .long ${num_ool_stubs_text_end}) SYM_CODE_START(ftrace_ool_stub_text_end) - .space ${num_ool_stubs_text} * FTRACE_OOL_STUB_SIZE + .space ${num_ool_stubs_text_end} * FTRACE_OOL_STUB_SIZE SYM_CODE_END(ftrace_ool_stub_text_end) .popsection