Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Youling Tang <tangyouling@loongson.cn>
To:     Josh Poimboeuf <jpoimboe@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Huacai Chen <chenhuacai@kernel.org>,
        madvenka@linux.microsoft.com
Cc:     chenzhongjin@huawei.com, WANG Xuerui <kernel@xen0n.name>,
        Xi Ruoyao <xry111@xry111.site>, live-patching@vger.kernel.org,
        linux-kernel@vger.kernel.org, loongarch@lists.linux.dev,
        tangyouling00@gmail.com, youling.tang@outlook.com,
        Jinyang He <hejinyang@loongson.cn>
Subject: [RFC PATCH v1 22/23] objtool: Make update_cfi_state() arch-specific function
Date:   Tue, 20 Jun 2023 16:18:31 +0800
Message-Id: <1687249112-2790-3-git-send-email-tangyouling@loongson.cn>
In-Reply-To: <1687249112-2790-1-git-send-email-tangyouling@loongson.cn>
References: <1687249112-2790-1-git-send-email-tangyouling@loongson.cn>
Precedence: bulk

Currently update_cfi_state() is implemented for the x86_64 architecture. This
function is specific to the architecture. In order to avoid powerpc build
errors, define x86_64 as the default implementation and rename update_cfi_state()
to arch_update_cfi_state().

LoongArch will reimplement arch_update_cfi_state().

Co-developed-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
---
 tools/objtool/arch/loongarch/decode.c | 76 +++++++++++++++++++++++++++
 tools/objtool/check.c                 | 10 ++--
 tools/objtool/include/objtool/arch.h  |  3 ++
 tools/objtool/include/objtool/check.h |  5 ++
 4 files changed, 89 insertions(+), 5 deletions(-)

diff --git a/tools/objtool/arch/loongarch/decode.c b/tools/objtool/arch/loongarch/decode.c
index 90adbbeab8d4..6ca8cbad6813 100644
--- a/tools/objtool/arch/loongarch/decode.c
+++ b/tools/objtool/arch/loongarch/decode.c
@@ -4,6 +4,8 @@
 #include <stdlib.h>
 
 #include <linux/bitops.h>
+#include <linux/objtool.h>
+
 #include <asm/inst.h>
 #include <asm/orc_types.h>
 
@@ -274,3 +276,77 @@ void arch_initial_func_cfi_state(struct cfi_init_state *state)
 	state->cfa.base = CFI_SP;
 	state->cfa.offset = 0;
 }
+
+
+int arch_update_cfi_state(struct instruction *insn,
+			  struct instruction *next_insn,
+			  struct cfi_state *cfi, struct stack_op *op)
+{
+	struct cfi_reg *cfa = &cfi->cfa;
+	struct cfi_reg *regs = cfi->regs;
+
+	/* stack operations don't make sense with an undefined CFA */
+	if (cfa->base == CFI_UNDEFINED) {
+		if (insn_func(insn)) {
+			WARN_FUNC("undefined stack state", insn->sec, insn->offset);
+			return -1;
+		}
+		return 0;
+	}
+
+	if (cfi->type == UNWIND_HINT_TYPE_REGS)
+		return update_cfi_state_regs(insn, cfi, op);
+
+
+	switch (op->dest.type) {
+	case OP_DEST_REG:
+		switch (op->src.type) {
+		case OP_SRC_ADD:
+			if (op->dest.reg == CFI_SP && op->src.reg == CFI_SP) {
+				/* addi.d sp, sp, imm */
+				cfi->stack_size -= op->src.offset;
+				if (cfa->base == CFI_SP)
+					cfa->offset -= op->src.offset;
+			} else if (op->dest.reg == CFI_FP && op->src.reg == CFI_SP) {
+				/* addi.d fp, sp, imm */
+				if (cfa->base == CFI_SP && cfa->offset == op->src.offset) {
+					cfa->base = CFI_FP;
+					cfa->offset = 0;
+				}
+			} else if (op->dest.reg == CFI_SP && op->src.reg == CFI_FP) {
+				/* addi.d sp, fp, imm */
+				if (cfa->base == CFI_FP && cfa->offset == 0) {
+					cfa->base = CFI_SP;
+					cfa->offset = -op->src.offset;
+				}
+			}
+			break;
+		case OP_SRC_REG_INDIRECT:
+			/* ld.d _reg, sp, imm */
+			if (op->src.reg == CFI_SP &&
+				op->src.offset == (regs[op->dest.reg].offset + cfi->stack_size)) {
+				restore_reg(cfi, op->dest.reg);
+				/* Gcc may not restore sp, we adjust it directly. */
+				if (cfa->base == CFI_FP && cfa->offset == 0) {
+					cfa->base = CFI_SP;
+					cfa->offset = cfi->stack_size;
+				}
+			}
+			break;
+		default:
+			break;
+		}
+		break;
+	case OP_DEST_REG_INDIRECT:
+		if (op->src.type == OP_SRC_REG)
+			/* st.d _reg, sp, imm */
+			if (op->dest.offset)
+				save_reg(cfi, op->src.reg, CFI_CFA, op->dest.offset - cfi->stack_size);
+		break;
+	default:
+		WARN_FUNC("unknown stack-related instruction", insn->sec, insn->offset);
+		return -1;
+	}
+
+	return 0;
+}
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index c637e54088f6..42f87a33f558 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -2230,7 +2230,7 @@ static bool has_valid_stack_frame(struct insn_state *state)
 	return false;
 }
 
-static int update_cfi_state_regs(struct instruction *insn,
+int update_cfi_state_regs(struct instruction *insn,
 				  struct cfi_state *cfi,
 				  struct stack_op *op)
 {
@@ -2255,7 +2255,7 @@ static int update_cfi_state_regs(struct instruction *insn,
 	return 0;
 }
 
-static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
+void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset)
 {
 	if (arch_callee_saved_reg(reg) &&
 	    cfi->regs[reg].base == CFI_UNDEFINED) {
@@ -2264,7 +2264,7 @@ static void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int off
 	}
 }
 
-static void restore_reg(struct cfi_state *cfi, unsigned char reg)
+void restore_reg(struct cfi_state *cfi, unsigned char reg)
 {
 	cfi->regs[reg].base = initial_func_cfi.regs[reg].base;
 	cfi->regs[reg].offset = initial_func_cfi.regs[reg].offset;
@@ -2323,7 +2323,7 @@ static void restore_reg(struct cfi_state *cfi, unsigned char reg)
  *   41 5d			pop    %r13
  *   c3				retq
  */
-static int update_cfi_state(struct instruction *insn,
+int __weak arch_update_cfi_state(struct instruction *insn,
 			    struct instruction *next_insn,
 			    struct cfi_state *cfi, struct stack_op *op)
 {
@@ -2795,7 +2795,7 @@ static int handle_insn_ops(struct instruction *insn,
 
 	for (op = insn->stack_ops; op; op = op->next) {
 
-		if (update_cfi_state(insn, next_insn, &state->cfi, op))
+		if (arch_update_cfi_state(insn, next_insn, &state->cfi, op))
 			return 1;
 
 		if (!insn->alt_group)
diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h
index 2b6d2ce4f9a5..88570c598752 100644
--- a/tools/objtool/include/objtool/arch.h
+++ b/tools/objtool/include/objtool/arch.h
@@ -95,4 +95,7 @@ int arch_rewrite_retpolines(struct objtool_file *file);
 
 bool arch_pc_relative_reloc(struct reloc *reloc);
 
+int __weak arch_update_cfi_state(struct instruction *insn,
+			    struct instruction *next_insn,
+			    struct cfi_state *cfi, struct stack_op *op);
 #endif /* _ARCH_H */
diff --git a/tools/objtool/include/objtool/check.h b/tools/objtool/include/objtool/check.h
index 34898364bf03..dd1b95c67620 100644
--- a/tools/objtool/include/objtool/check.h
+++ b/tools/objtool/include/objtool/check.h
@@ -33,4 +33,9 @@ struct alt_group {
 
 extern unsigned long nr_insns;
 
+int update_cfi_state_regs(struct instruction *insn,
+				  struct cfi_state *cfi,
+				  struct stack_op *op);
+void save_reg(struct cfi_state *cfi, unsigned char reg, int base, int offset);
+void restore_reg(struct cfi_state *cfi, unsigned char reg);
 #endif /* _CHECK_H */
-- 
2.39.2