From patchwork Fri Sep 16 10:38:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guo Ren X-Patchwork-Id: 12978381 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D8B9DC54EE9 for ; Fri, 16 Sep 2022 10:40:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=QZygYhYE0w8AnN8G84lSo4PXAZwT3WT9BZ5vohF3WZA=; b=R/a7fK4qwrPLv0 OV9LDaubkADAnphtcRmrOajvi8MwIKJkOKaDrBwzj9P8h9Te3FFStg0uRTEFdR1QF4s7RnZ6GSa/J t54cWxXODT3qb/ZsFCW0olQ/JxW02U3Hw1sX8OTmNc9nvxZc0DKxjWW4P1/c4k2/iqOegHT7IFVOe OtWb8vBnskmIPGR2w7DMQEl5s6HNlIZ21ZqSpMEgF5zHt3265xuE6IbVB3QHuz8oZUW/XNqwade9Z ldL+6spZiQC/B0XJF/npOwGHqYK7dG/Ap6hG2B1zMzgSnVkVmy94jZCCZA7gMGvly26kQdmk90OSk fjgHiAmFzTeR3B4v/BuQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oZ8lc-00CGsY-9M; Fri, 16 Sep 2022 10:40:16 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oZ8kG-00CGHg-3B for linux-riscv@lists.infradead.org; Fri, 16 Sep 2022 10:38:57 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 64F6CB825E8; Fri, 16 Sep 2022 10:38:50 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 11ACAC433C1; Fri, 16 Sep 2022 10:38:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1663324729; bh=kL47KPMguqI2L3KF27fbBlhWO4R1JWIXY+6u1ZR4dSo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QYS/ZfVevAe7v9zvnVPryLFsMR2MryF1Hoo+uX4L3qJ0JnM/g2G0Te9tdsak6NJ3y iDaWAT8cKXoxmhMqSFOW2+Lm+HOh+FXT7Z4t/2dtRHGoMups9h8XqMmP8/2g2rmF+I oH58hH8Ke1VpcyAxpFRCgtygzwA+LoJ4usMDFvTCXHThDJ9bTRW5OnoasSInELGqDQ p6++El6uukwBHQEgykF2EunuK2KIrqluUC30Duzj90Rq1LiaZo/kGyRLQT55SzL4GD cKygP4MHFg4ns9R1ilmSTYMEfWm2Z5mo7GBNid3SuKtt0wmWj8zWgxB5eFgtUO1C0T 0BmzvWQmE0WuQ== From: guoren@kernel.org To: arnd@arndb.de, guoren@kernel.org, palmer@rivosinc.com, rostedt@goodmis.org, andy.chiu@sifive.com, greentime.hu@sifive.com, zong.li@sifive.com, jrtc27@jrtc27.com, mingo@redhat.com Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Guo Ren Subject: [PATCH 3/3] riscv: ftrace: Reduce the detour code size to half Date: Fri, 16 Sep 2022 06:38:17 -0400 Message-Id: <20220916103817.9490-4-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20220916103817.9490-1-guoren@kernel.org> References: <20220916103817.9490-1-guoren@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220916_033852_528596_1FAF31A7 X-CRM114-Status: GOOD ( 20.03 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org From: Guo Ren Use a temporary register to reduce the size of detour code from 16B to 8B. Before optimization (16 byte): : 0: REG_S ra, -SZREG(sp) 4: auipc ra, ? 8: jalr ?(ra) 12: REG_L ra, -SZREG(sp) (func_boddy) The previous implementation is from afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT") After optimization (8 byte): : 0: auipc t0, ? 4: jalr t0, ?(t0) (func_boddy) Signed-off-by: Guo Ren Signed-off-by: Guo Ren --- arch/riscv/Makefile | 4 +- arch/riscv/include/asm/ftrace.h | 46 ++++++++++++++++++----- arch/riscv/kernel/ftrace.c | 65 ++++++++++----------------------- arch/riscv/kernel/mcount-dyn.S | 43 +++++++++------------- 4 files changed, 74 insertions(+), 84 deletions(-) diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index f32844f545d6..7b9d4a7cd4bf 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -12,9 +12,9 @@ ifeq ($(CONFIG_DYNAMIC_FTRACE),y) LDFLAGS_vmlinux := --no-relax KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY ifeq ($(CONFIG_RISCV_ISA_C),y) - CC_FLAGS_FTRACE := -fpatchable-function-entry=8 -else CC_FLAGS_FTRACE := -fpatchable-function-entry=4 +else + CC_FLAGS_FTRACE := -fpatchable-function-entry=2 endif endif diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h index 04dad3380041..34b0b523865a 100644 --- a/arch/riscv/include/asm/ftrace.h +++ b/arch/riscv/include/asm/ftrace.h @@ -42,6 +42,14 @@ struct dyn_arch_ftrace { * 2) jalr: setting low-12 offset to ra, jump to ra, and set ra to * return address (original pc + 4) * + *: + * 0: auipc t0/ra, 0x? + * 4: jalr t0/ra, ?(t0/ra) + * + *: + * 0: nop + * 4: nop + * * Dynamic ftrace generates probes to call sites, so we must deal with * both auipc and jalr at the same time. */ @@ -52,25 +60,43 @@ struct dyn_arch_ftrace { #define AUIPC_OFFSET_MASK (0xfffff000) #define AUIPC_PAD (0x00001000) #define JALR_SHIFT 20 -#define JALR_BASIC (0x000080e7) -#define AUIPC_BASIC (0x00000097) +#define JALR_RA (0x000080e7) +#define AUIPC_RA (0x00000097) +#define JALR_T0 (0x000282e7) +#define AUIPC_T0 (0x00000297) #define NOP4 (0x00000013) -#define make_call(caller, callee, call) \ +#define to_jalr_t0(offset) \ + (((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_T0) + +#define to_auipc_t0(offset) \ + ((offset & JALR_SIGN_MASK) ? \ + (((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_T0) : \ + ((offset & AUIPC_OFFSET_MASK) | AUIPC_T0)) + +#define make_call_t0(caller, callee, call) \ do { \ - call[0] = to_auipc_insn((unsigned int)((unsigned long)callee - \ + call[0] = to_auipc_t0((unsigned int)((unsigned long)callee - \ (unsigned long)caller)); \ - call[1] = to_jalr_insn((unsigned int)((unsigned long)callee - \ + call[1] = to_jalr_t0((unsigned int)((unsigned long)callee - \ (unsigned long)caller)); \ } while (0) -#define to_jalr_insn(offset) \ - (((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_BASIC) +#define to_jalr_ra(offset) \ + (((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_RA) -#define to_auipc_insn(offset) \ +#define to_auipc_ra(offset) \ ((offset & JALR_SIGN_MASK) ? \ - (((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_BASIC) : \ - ((offset & AUIPC_OFFSET_MASK) | AUIPC_BASIC)) + (((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_RA) : \ + ((offset & AUIPC_OFFSET_MASK) | AUIPC_RA)) + +#define make_call_ra(caller, callee, call) \ +do { \ + call[0] = to_auipc_ra((unsigned int)((unsigned long)callee - \ + (unsigned long)caller)); \ + call[1] = to_jalr_ra((unsigned int)((unsigned long)callee - \ + (unsigned long)caller)); \ +} while (0) /* * Let auipc+jalr be the basic *mcount unit*, so we make it 8 bytes here. diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c index 2086f6585773..8c77f236fc71 100644 --- a/arch/riscv/kernel/ftrace.c +++ b/arch/riscv/kernel/ftrace.c @@ -55,12 +55,15 @@ static int ftrace_check_current_call(unsigned long hook_pos, } static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target, - bool enable) + bool enable, bool ra) { unsigned int call[2]; unsigned int nops[2] = {NOP4, NOP4}; - make_call(hook_pos, target, call); + if (ra) + make_call_ra(hook_pos, target, call); + else + make_call_t0(hook_pos, target, call); /* Replace the auipc-jalr pair at once. Return -EPERM on write error. */ if (patch_text_nosync @@ -70,42 +73,13 @@ static int __ftrace_modify_call(unsigned long hook_pos, unsigned long target, return 0; } -/* - * Put 5 instructions with 16 bytes at the front of function within - * patchable function entry nops' area. - * - * 0: REG_S ra, -SZREG(sp) - * 1: auipc ra, 0x? - * 2: jalr -?(ra) - * 3: REG_L ra, -SZREG(sp) - * - * So the opcodes is: - * 0: 0xfe113c23 (sd)/0xfe112e23 (sw) - * 1: 0x???????? -> auipc - * 2: 0x???????? -> jalr - * 3: 0xff813083 (ld)/0xffc12083 (lw) - */ -#if __riscv_xlen == 64 -#define INSN0 0xfe113c23 -#define INSN3 0xff813083 -#elif __riscv_xlen == 32 -#define INSN0 0xfe112e23 -#define INSN3 0xffc12083 -#endif - -#define FUNC_ENTRY_SIZE 16 -#define FUNC_ENTRY_JMP 4 - int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { - unsigned int call[4] = {INSN0, 0, 0, INSN3}; - unsigned long target = addr; - unsigned long caller = rec->ip + FUNC_ENTRY_JMP; + unsigned int call[2]; - call[1] = to_auipc_insn((unsigned int)(target - caller)); - call[2] = to_jalr_insn((unsigned int)(target - caller)); + make_call_t0(rec->ip, addr, call); - if (patch_text_nosync((void *)rec->ip, call, FUNC_ENTRY_SIZE)) + if (patch_text_nosync((void *)rec->ip, call, 8)) return -EPERM; return 0; @@ -114,15 +88,14 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { - unsigned int nops[4] = {NOP4, NOP4, NOP4, NOP4}; + unsigned int nops[2] = {NOP4, NOP4}; - if (patch_text_nosync((void *)rec->ip, nops, FUNC_ENTRY_SIZE)) + if (patch_text_nosync((void *)rec->ip, nops, MCOUNT_INSN_SIZE)) return -EPERM; return 0; } - /* * This is called early on, and isn't wrapped by * ftrace_arch_code_modify_{prepare,post_process}() and therefor doesn't hold @@ -144,10 +117,10 @@ int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) int ftrace_update_ftrace_func(ftrace_func_t func) { int ret = __ftrace_modify_call((unsigned long)&ftrace_call, - (unsigned long)func, true); + (unsigned long)func, true, true); if (!ret) { ret = __ftrace_modify_call((unsigned long)&ftrace_regs_call, - (unsigned long)func, true); + (unsigned long)func, true, true); } return ret; @@ -159,16 +132,16 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr) { unsigned int call[2]; - unsigned long caller = rec->ip + FUNC_ENTRY_JMP; + unsigned long caller = rec->ip + 4; int ret; - make_call(caller, old_addr, call); + make_call_t0(caller, old_addr, call); ret = ftrace_check_current_call(caller, call); if (ret) return ret; - return __ftrace_modify_call(caller, addr, true); + return __ftrace_modify_call(caller, addr, true, false); } #endif @@ -203,12 +176,12 @@ int ftrace_enable_ftrace_graph_caller(void) int ret; ret = __ftrace_modify_call((unsigned long)&ftrace_graph_call, - (unsigned long)&prepare_ftrace_return, true); + (unsigned long)&prepare_ftrace_return, true, true); if (ret) return ret; return __ftrace_modify_call((unsigned long)&ftrace_graph_regs_call, - (unsigned long)&prepare_ftrace_return, true); + (unsigned long)&prepare_ftrace_return, true, true); } int ftrace_disable_ftrace_graph_caller(void) @@ -216,12 +189,12 @@ int ftrace_disable_ftrace_graph_caller(void) int ret; ret = __ftrace_modify_call((unsigned long)&ftrace_graph_call, - (unsigned long)&prepare_ftrace_return, false); + (unsigned long)&prepare_ftrace_return, false, true); if (ret) return ret; return __ftrace_modify_call((unsigned long)&ftrace_graph_regs_call, - (unsigned long)&prepare_ftrace_return, false); + (unsigned long)&prepare_ftrace_return, false, true); } #endif /* CONFIG_DYNAMIC_FTRACE */ #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ diff --git a/arch/riscv/kernel/mcount-dyn.S b/arch/riscv/kernel/mcount-dyn.S index d171eca623b6..64bc79816f5e 100644 --- a/arch/riscv/kernel/mcount-dyn.S +++ b/arch/riscv/kernel/mcount-dyn.S @@ -13,8 +13,8 @@ .text -#define FENTRY_RA_OFFSET 12 -#define ABI_SIZE_ON_STACK 72 +#define FENTRY_RA_OFFSET 8 +#define ABI_SIZE_ON_STACK 80 #define ABI_A0 0 #define ABI_A1 8 #define ABI_A2 16 @@ -23,10 +23,10 @@ #define ABI_A5 40 #define ABI_A6 48 #define ABI_A7 56 -#define ABI_RA 64 +#define ABI_T0 64 +#define ABI_RA 72 .macro SAVE_ABI - addi sp, sp, -SZREG addi sp, sp, -ABI_SIZE_ON_STACK REG_S a0, ABI_A0(sp) @@ -37,6 +37,7 @@ REG_S a5, ABI_A5(sp) REG_S a6, ABI_A6(sp) REG_S a7, ABI_A7(sp) + REG_S t0, ABI_T0(sp) REG_S ra, ABI_RA(sp) .endm @@ -49,24 +50,18 @@ REG_L a5, ABI_A5(sp) REG_L a6, ABI_A6(sp) REG_L a7, ABI_A7(sp) + REG_L t0, ABI_T0(sp) REG_L ra, ABI_RA(sp) addi sp, sp, ABI_SIZE_ON_STACK - addi sp, sp, SZREG .endm #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS .macro SAVE_ALL - addi sp, sp, -SZREG addi sp, sp, -PT_SIZE_ON_STACK - REG_S x1, PT_EPC(sp) - addi sp, sp, PT_SIZE_ON_STACK - REG_L x1, (sp) - addi sp, sp, -PT_SIZE_ON_STACK + REG_S t0, PT_EPC(sp) REG_S x1, PT_RA(sp) - REG_L x1, PT_EPC(sp) - REG_S x2, PT_SP(sp) REG_S x3, PT_GP(sp) REG_S x4, PT_TP(sp) @@ -100,11 +95,8 @@ .endm .macro RESTORE_ALL + REG_L t0, PT_EPC(sp) REG_L x1, PT_RA(sp) - addi sp, sp, PT_SIZE_ON_STACK - REG_S x1, (sp) - addi sp, sp, -PT_SIZE_ON_STACK - REG_L x1, PT_EPC(sp) REG_L x2, PT_SP(sp) REG_L x3, PT_GP(sp) REG_L x4, PT_TP(sp) @@ -137,17 +129,16 @@ REG_L x31, PT_T6(sp) addi sp, sp, PT_SIZE_ON_STACK - addi sp, sp, SZREG .endm #endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ ENTRY(ftrace_caller) SAVE_ABI - addi a0, ra, -FENTRY_RA_OFFSET + addi a0, t0, -FENTRY_RA_OFFSET la a1, function_trace_op REG_L a2, 0(a1) - REG_L a1, ABI_SIZE_ON_STACK(sp) + mv a1, ra mv a3, sp ftrace_call: @@ -155,8 +146,8 @@ ftrace_call: call ftrace_stub #ifdef CONFIG_FUNCTION_GRAPH_TRACER - addi a0, sp, ABI_SIZE_ON_STACK - REG_L a1, ABI_RA(sp) + addi a0, sp, ABI_RA + REG_L a1, ABI_T0(sp) addi a1, a1, -FENTRY_RA_OFFSET #ifdef HAVE_FUNCTION_GRAPH_FP_TEST mv a2, s0 @@ -166,17 +157,17 @@ ftrace_graph_call: call ftrace_stub #endif RESTORE_ABI - ret + jr t0 ENDPROC(ftrace_caller) #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS ENTRY(ftrace_regs_caller) SAVE_ALL - addi a0, ra, -FENTRY_RA_OFFSET + addi a0, t0, -FENTRY_RA_OFFSET la a1, function_trace_op REG_L a2, 0(a1) - REG_L a1, PT_SIZE_ON_STACK(sp) + REG_L a1, PT_RA(sp) mv a3, sp ftrace_regs_call: @@ -185,7 +176,7 @@ ftrace_regs_call: #ifdef CONFIG_FUNCTION_GRAPH_TRACER addi a0, sp, PT_RA - REG_L a1, PT_EPC(sp) + REG_L a1, PT_T0(sp) addi a1, a1, -FENTRY_RA_OFFSET #ifdef HAVE_FUNCTION_GRAPH_FP_TEST mv a2, s0 @@ -196,6 +187,6 @@ ftrace_graph_regs_call: #endif RESTORE_ALL - ret + jr t0 ENDPROC(ftrace_regs_caller) #endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */