[RFC PATCH 7/9] arm64: ftrace: Revert "fix unreachable PLT for ftrace_caller ..."

[Ard Biesheuvel <ardb+git@google.com>]

From: Ard Biesheuvel <ardb@kernel.org>

This reverts commit a7ed7b9d0ebb038db9963d574da0311cab0b666a, which is
no longer needed now that the corner case where .init.text is placed out
of direct branching range from .text of the same module can no longer
occur.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/include/asm/module.h     |  1 -
 arch/arm64/include/asm/module.lds.h |  1 -
 arch/arm64/kernel/ftrace.c          | 13 +++----------
 arch/arm64/kernel/module-plts.c     | 12 +-----------
 arch/arm64/kernel/module.c          | 11 -----------
 5 files changed, 4 insertions(+), 34 deletions(-)

diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h
index fb9b88eebeb1..79550b22ba19 100644
--- a/arch/arm64/include/asm/module.h
+++ b/arch/arm64/include/asm/module.h
@@ -19,7 +19,6 @@ struct mod_arch_specific {
 
 	/* for CONFIG_DYNAMIC_FTRACE */
 	struct plt_entry	*ftrace_trampolines;
-	struct plt_entry	*init_ftrace_trampolines;
 };
 
 u64 module_emit_plt_entry(struct module *mod, Elf64_Shdr *sechdrs,
diff --git a/arch/arm64/include/asm/module.lds.h b/arch/arm64/include/asm/module.lds.h
index 0b3aacd22c59..0c3aea98e116 100644
--- a/arch/arm64/include/asm/module.lds.h
+++ b/arch/arm64/include/asm/module.lds.h
@@ -2,7 +2,6 @@ SECTIONS {
 	.plt 0 : { BYTE(0) }
 	.init.plt 0 : { BYTE(0) }
 	.text.ftrace_trampoline 0 : { BYTE(0) }
-	.init.text.ftrace_trampoline 0 : { BYTE(0) }
 
 #ifdef CONFIG_KASAN_SW_TAGS
 	/*
diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c
index 5a1554a44162..b56da24c1be4 100644
--- a/arch/arm64/kernel/ftrace.c
+++ b/arch/arm64/kernel/ftrace.c
@@ -258,17 +258,10 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 	return ftrace_modify_code(pc, 0, new, false);
 }
 
-static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr)
+static struct plt_entry *get_ftrace_plt(struct module *mod)
 {
 #ifdef CONFIG_MODULES
-	struct plt_entry *plt = NULL;
-
-	if (within_module_mem_type(addr, mod, MOD_INIT_TEXT))
-		plt = mod->arch.init_ftrace_trampolines;
-	else if (within_module_mem_type(addr, mod, MOD_TEXT))
-		plt = mod->arch.ftrace_trampolines;
-	else
-		return NULL;
+	struct plt_entry *plt = mod->arch.ftrace_trampolines;
 
 	return &plt[FTRACE_PLT_IDX];
 #else
@@ -339,7 +332,7 @@ static bool ftrace_find_callable_addr(struct dyn_ftrace *rec,
 	if (WARN_ON(!mod))
 		return false;
 
-	plt = get_ftrace_plt(mod, pc);
+	plt = get_ftrace_plt(mod);
 	if (!plt) {
 		pr_err("ftrace: no module PLT for %ps\n", (void *)*addr);
 		return false;
diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c
index 7afd370da9f4..bde32979c06a 100644
--- a/arch/arm64/kernel/module-plts.c
+++ b/arch/arm64/kernel/module-plts.c
@@ -283,7 +283,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 	unsigned long core_plts = 0;
 	unsigned long init_plts = 0;
 	Elf64_Sym *syms = NULL;
-	Elf_Shdr *pltsec, *tramp = NULL, *init_tramp = NULL;
+	Elf_Shdr *pltsec, *tramp = NULL;
 	int i;
 
 	/*
@@ -298,9 +298,6 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 		else if (!strcmp(secstrings + sechdrs[i].sh_name,
 				 ".text.ftrace_trampoline"))
 			tramp = sechdrs + i;
-		else if (!strcmp(secstrings + sechdrs[i].sh_name,
-				 ".init.text.ftrace_trampoline"))
-			init_tramp = sechdrs + i;
 		else if (sechdrs[i].sh_type == SHT_SYMTAB)
 			syms = (Elf64_Sym *)sechdrs[i].sh_addr;
 	}
@@ -366,12 +363,5 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 		tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
 	}
 
-	if (init_tramp) {
-		init_tramp->sh_type = SHT_NOBITS;
-		init_tramp->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
-		init_tramp->sh_addralign = __alignof__(struct plt_entry);
-		init_tramp->sh_size = NR_FTRACE_PLTS * sizeof(struct plt_entry);
-	}
-
 	return 0;
 }
diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c
index 24adb581af0e..6e5b488a219e 100644
--- a/arch/arm64/kernel/module.c
+++ b/arch/arm64/kernel/module.c
@@ -466,17 +466,6 @@ static int module_init_ftrace_plt(const Elf_Ehdr *hdr,
 	__init_plt(&plts[FTRACE_PLT_IDX], FTRACE_ADDR);
 
 	mod->arch.ftrace_trampolines = plts;
-
-	s = find_section(hdr, sechdrs, ".init.text.ftrace_trampoline");
-	if (!s)
-		return -ENOEXEC;
-
-	plts = (void *)s->sh_addr;
-
-	__init_plt(&plts[FTRACE_PLT_IDX], FTRACE_ADDR);
-
-	mod->arch.init_ftrace_trampolines = plts;
-
 #endif
 	return 0;
 }
-- 
2.55.0.860.g4b6b3295ed-goog