From: Naveen N Rao <naveen@xxxxxxxxxx> 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 <naveen@xxxxxxxxxx> Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxx> --- Changes in v6: * Updated with Masahiro's suggestions at https://lore.kernel.org/all/CAK7LNAREkj5OQ_HA2H=iV_32qdOcaguCOBKV1j+dJW0YaQh3UA@xxxxxxxxxxxxxx/ 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 | 3 ++- arch/powerpc/tools/ftrace-gen-ool-stubs.sh | 19 +++++++++++++------ 6 files changed, 56 insertions(+), 13 deletions(-) diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 26e3060e44f4..2e347f682c15 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -573,6 +573,18 @@ config PPC_FTRACE_OUT_OF_LINE def_bool PPC64 && ARCH_USING_PATCHABLE_FUNCTION_ENTRY 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" + depends on PPC_FTRACE_OUT_OF_LINE + default 32768 + 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 d2e7ecd5f46f..e1f7afcd9fdf 100644 --- a/arch/powerpc/tools/Makefile +++ b/arch/powerpc/tools/Makefile @@ -1,7 +1,8 @@ # SPDX-License-Identifier: GPL-2.0-or-later quiet_cmd_gen_ftrace_ool_stubs = GEN $@ - cmd_gen_ftrace_ool_stubs = $< "$(CONFIG_64BIT)" "$(OBJDUMP)" vmlinux.o $@ + cmd_gen_ftrace_ool_stubs = $< "$(CONFIG_PPC_FTRACE_OUT_OF_LINE_NUM_RESERVE)" "$(CONFIG_64BIT)" \ + "$(OBJDUMP)" 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 96e1ca5803e4..3ea0f23f2501 100755 --- a/arch/powerpc/tools/ftrace-gen-ool-stubs.sh +++ b/arch/powerpc/tools/ftrace-gen-ool-stubs.sh @@ -4,10 +4,11 @@ # Error out on error set -e -is_64bit="$1" -objdump="$2" -vmlinux_o="$3" -arch_vmlinux_S="$4" +num_ool_stubs_text_builtin="$1" +is_64bit="$2" +objdump="$3" +vmlinux_o="$4" +arch_vmlinux_S="$5" RELOCATION=R_PPC64_ADDR64 if [ -z "$is_64bit" ]; then @@ -19,15 +20,21 @@ num_ool_stubs_text=$($objdump -r -j __patchable_function_entries "$vmlinux_o" | num_ool_stubs_inittext=$($objdump -r -j __patchable_function_entries "$vmlinux_o" | grep ".init.text" | grep -c "$RELOCATION") +if [ "$num_ool_stubs_text" -gt "$num_ool_stubs_text_builtin" ]; then + num_ool_stubs_text_end=$((num_ool_stubs_text - num_ool_stubs_text_builtin)) +else + num_ool_stubs_text_end=0 +fi + cat > "$arch_vmlinux_S" <<EOF #include <asm/asm-offsets.h> #include <linux/linkage.h> .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 -- 2.47.0
