linux-kernel - [PATCH v1 7/7] riscv: kernel/modules.c simplification

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-Id: <20220131182145.236005-8-kernel@esmil.dk>
Date:   Mon, 31 Jan 2022 19:21:45 +0100
From:   Emil Renner Berthing <kernel@...il.dk>
To:     linux-riscv@...ts.infradead.org
Cc:     Emil Renner Berthing <kernel@...il.dk>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Jason Baron <jbaron@...mai.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ard Biesheuvel <ardb@...nel.org>,
        Alexandre Ghiti <alex@...ti.fr>,
        Jisheng Zhang <jszhang@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v1 7/7] riscv: kernel/modules.c simplification

Signed-off-by: Emil Renner Berthing <kernel@...il.dk>
---
 arch/riscv/kernel/module.c | 93 ++++++++++++++++----------------------
 1 file changed, 39 insertions(+), 54 deletions(-)

diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
index 2212d88776e0..e371977aecfd 100644
--- a/arch/riscv/kernel/module.c
+++ b/arch/riscv/kernel/module.c
@@ -298,24 +298,23 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 		       unsigned int symindex, unsigned int relsec,
 		       struct module *me)
 {
-	Elf_Rela *rel = (void *) sechdrs[relsec].sh_addr;
-	int (*handler)(struct module *me, void *location, Elf_Addr v);
-	Elf_Sym *sym;
-	void *location;
-	unsigned int i, type;
-	Elf_Addr v;
-	int res;
+	Elf_Rela *rel = (void *)sechdrs[relsec].sh_addr;
+	unsigned int entries = sechdrs[relsec].sh_size / sizeof(*rel);
+	unsigned int i;
 
 	pr_debug("Applying relocate section %u to %u\n", relsec,
 	       sechdrs[relsec].sh_info);
 
-	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
-		/* This is where to make the change */
-		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
-			+ rel[i].r_offset;
-		/* This is the symbol it is referring to */
-		sym = (Elf_Sym *)sechdrs[symindex].sh_addr
+	for (i = 0; i < entries; i++) {
+		Elf_Sym *sym = (Elf_Sym *)sechdrs[symindex].sh_addr
 			+ ELF_RISCV_R_SYM(rel[i].r_info);
+		Elf_Addr loc = sechdrs[sechdrs[relsec].sh_info].sh_addr
+			+ rel[i].r_offset;
+		unsigned int type = ELF_RISCV_R_TYPE(rel[i].r_info);
+		int (*handler)(struct module *me, void *location, Elf_Addr v);
+		Elf_Addr v;
+		int res;
+
 		if (IS_ERR_VALUE(sym->st_value)) {
 			/* Ignore unresolved weak symbol */
 			if (ELF_ST_BIND(sym->st_info) == STB_WEAK)
@@ -325,8 +324,6 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 			return -ENOENT;
 		}
 
-		type = ELF_RISCV_R_TYPE(rel[i].r_info);
-
 		if (type < ARRAY_SIZE(reloc_handlers_rela))
 			handler = reloc_handlers_rela[type];
 		else
@@ -343,48 +340,36 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
 		if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) {
 			unsigned int j;
 
-			for (j = 0; j < sechdrs[relsec].sh_size / sizeof(*rel); j++) {
-				unsigned long hi20_loc =
-					sechdrs[sechdrs[relsec].sh_info].sh_addr
+			/* find the corresponding HI20 entry */
+			for (j = 0; j < entries; j++) {
+				Elf_Sym *hi20_sym = (Elf_Sym *)sechdrs[symindex].sh_addr
+					+ ELF_RISCV_R_SYM(rel[j].r_info);
+				Elf_Addr hi20_loc = sechdrs[sechdrs[relsec].sh_info].sh_addr
 					+ rel[j].r_offset;
-				u32 hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info);
-
-				/* Find the corresponding HI20 relocation entry */
-				if (hi20_loc == sym->st_value
-				    && (hi20_type == R_RISCV_PCREL_HI20
-					|| hi20_type == R_RISCV_GOT_HI20)) {
-					s32 hi20, lo12;
-					Elf_Sym *hi20_sym =
-						(Elf_Sym *)sechdrs[symindex].sh_addr
-						+ ELF_RISCV_R_SYM(rel[j].r_info);
-					unsigned long hi20_sym_val =
-						hi20_sym->st_value
-						+ rel[j].r_addend;
-
-					/* Calculate lo12 */
-					size_t offset = hi20_sym_val - hi20_loc;
-					if (IS_ENABLED(CONFIG_MODULE_SECTIONS)
-					    && hi20_type == R_RISCV_GOT_HI20) {
-						offset = module_emit_got_entry(
-							 me, hi20_sym_val);
-						offset = offset - hi20_loc;
-					}
-					hi20 = (offset + 0x800) & 0xfffff000;
-					lo12 = offset - hi20;
-					v = lo12;
-
-					break;
-				}
-			}
-			if (j == sechdrs[relsec].sh_size / sizeof(*rel)) {
-				pr_err(
-				  "%s: Can not find HI20 relocation information\n",
-				  me->name);
-				return -EINVAL;
+				unsigned int hi20_type = ELF_RISCV_R_TYPE(rel[j].r_info);
+
+				if (hi20_loc != sym->st_value ||
+						(hi20_type != R_RISCV_PCREL_HI20 &&
+						 hi20_type != R_RISCV_GOT_HI20))
+					continue;
+
+				/* calculate relative offset */
+				v = hi20_sym->st_value + rel[j].r_addend;
+
+				if (IS_ENABLED(CONFIG_MODULE_SECTIONS) &&
+						hi20_type == R_RISCV_GOT_HI20)
+					v = module_emit_got_entry(me, v);
+
+				v -= hi20_loc;
+				goto handle_reloc;
 			}
-		}
 
-		res = handler(me, location, v);
+			pr_err("%s: Cannot find HI20 relocation information\n",
+					me->name);
+			return -EINVAL;
+		}
+handle_reloc:
+		res = handler(me, (void *)loc, v);
 		if (res)
 			return res;
 	}
-- 
2.35.1