1 files changed, 38 insertions, 11 deletions

diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c
index 6e626abaefc5..1fc309b41f94 100644
--- a/arch/arm/kernel/module-plts.c
+++ b/arch/arm/kernel/module-plts.c
@@ -4,6 +4,7 @@
  */
 
 #include <linux/elf.h>
+#include <linux/ftrace.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/sort.h>
@@ -12,10 +13,6 @@
 #include <asm/cache.h>
 #include <asm/opcodes.h>
 
-#define PLT_ENT_STRIDE		L1_CACHE_BYTES
-#define PLT_ENT_COUNT		(PLT_ENT_STRIDE / sizeof(u32))
-#define PLT_ENT_SIZE		(sizeof(struct plt_entries) / PLT_ENT_COUNT)
-
 #ifdef CONFIG_THUMB2_KERNEL
 #define PLT_ENT_LDR		__opcode_to_mem_thumb32(0xf8dff000 | \
 							(PLT_ENT_STRIDE - 4))
@@ -24,9 +21,11 @@
 						    (PLT_ENT_STRIDE - 8))
 #endif
 
-struct plt_entries {
-	u32	ldr[PLT_ENT_COUNT];
-	u32	lit[PLT_ENT_COUNT];
+static const u32 fixed_plts[] = {
+#ifdef CONFIG_DYNAMIC_FTRACE
+	FTRACE_ADDR,
+	MCOUNT_ADDR,
+#endif
 };
 
 static bool in_init(const struct module *mod, unsigned long loc)
@@ -34,14 +33,40 @@ static bool in_init(const struct module *mod, unsigned long loc)
 	return loc - (u32)mod->init_layout.base < mod->init_layout.size;
 }
 
+static void prealloc_fixed(struct mod_plt_sec *pltsec, struct plt_entries *plt)
+{
+	int i;
+
+	if (!ARRAY_SIZE(fixed_plts) || pltsec->plt_count)
+		return;
+	pltsec->plt_count = ARRAY_SIZE(fixed_plts);
+
+	for (i = 0; i < ARRAY_SIZE(plt->ldr); ++i)
+		plt->ldr[i] = PLT_ENT_LDR;
+
+	BUILD_BUG_ON(sizeof(fixed_plts) > sizeof(plt->lit));
+	memcpy(plt->lit, fixed_plts, sizeof(fixed_plts));
+}
+
 u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val)
 {
 	struct mod_plt_sec *pltsec = !in_init(mod, loc) ? &mod->arch.core :
 							  &mod->arch.init;
+	struct plt_entries *plt;
+	int idx;
+
+	/* cache the address, ELF header is available only during module load */
+	if (!pltsec->plt_ent)
+		pltsec->plt_ent = (struct plt_entries *)pltsec->plt->sh_addr;
+	plt = pltsec->plt_ent;
 
-	struct plt_entries *plt = (struct plt_entries *)pltsec->plt->sh_addr;
-	int idx = 0;
+	prealloc_fixed(pltsec, plt);
+
+	for (idx = 0; idx < ARRAY_SIZE(fixed_plts); ++idx)
+		if (plt->lit[idx] == val)
+			return (u32)&plt->ldr[idx];
 
+	idx = 0;
 	/*
 	 * Look for an existing entry pointing to 'val'. Given that the
 	 * relocations are sorted, this will be the last entry we allocated.
@@ -189,8 +214,8 @@ static unsigned int count_plts(const Elf32_Sym *syms, Elf32_Addr base,
 int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 			      char *secstrings, struct module *mod)
 {
-	unsigned long core_plts = 0;
-	unsigned long init_plts = 0;
+	unsigned long core_plts = ARRAY_SIZE(fixed_plts);
+	unsigned long init_plts = ARRAY_SIZE(fixed_plts);
 	Elf32_Shdr *s, *sechdrs_end = sechdrs + ehdr->e_shnum;
 	Elf32_Sym *syms = NULL;
 
@@ -245,6 +270,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 	mod->arch.core.plt->sh_size = round_up(core_plts * PLT_ENT_SIZE,
 					       sizeof(struct plt_entries));
 	mod->arch.core.plt_count = 0;
+	mod->arch.core.plt_ent = NULL;
 
 	mod->arch.init.plt->sh_type = SHT_NOBITS;
 	mod->arch.init.plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
@@ -252,6 +278,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
 	mod->arch.init.plt->sh_size = round_up(init_plts * PLT_ENT_SIZE,
 					       sizeof(struct plt_entries));
 	mod->arch.init.plt_count = 0;
+	mod->arch.init.plt_ent = NULL;
 
 	pr_debug("%s: plt=%x, init.plt=%x\n", __func__,
 		 mod->arch.core.plt->sh_size, mod->arch.init.plt->sh_size);