llext: Add parameters to arch_elf_relocate

The RISC-V port of llext requires additional parameters for handling non-adjacent HI20/LO12 relocations in arch_elf_relocate(): the current extension (struct llext), the current extension loader (struct llext_loader), the current section header (elf_shdr_t) and the current symbol (elf_sym_t). This changes the signature of arch_elf_relocate accordingly. Signed-off-by: Eric Ackermann <[email protected]>
zephyrproject-rtos · Feb 18, 2025 · 6d9b0c0 · 6d9b0c0
1 parent 37f5100
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Showing 7 changed files with 58 additions and 30 deletions.
diff --git a/arch/arc/core/elf.c b/arch/arc/core/elf.c
@@ -6,6 +6,7 @@
 
 #include <zephyr/llext/elf.h>
 #include <zephyr/llext/llext.h>
+#include <zephyr/llext/llext_internal.h>
 #include <zephyr/llext/loader.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/sys/util.h>
@@ -31,12 +32,18 @@ LOG_MODULE_REGISTER(elf, CONFIG_LLEXT_LOG_LEVEL);
  * https://github.com/foss-for-synopsys-dwc-arc-processors/arc-ABI-manual/blob/master/ARCv2_ABI.pdf
  * https://github.com/zephyrproject-rtos/binutils-gdb
  */
-int arch_elf_relocate(elf_rela_t *rel, uintptr_t loc, uintptr_t sym_base_addr, const char *sym_name,
-		      uintptr_t load_bias)
+int arch_elf_relocate(struct llext_loader *ldr, const struct llext *ext, elf_rela_t *rel,
+		      const elf_shdr_t *shdr, const elf_sym_t *sym, uintptr_t loc,
+		      uintptr_t sym_base_addr, const char *sym_name)
 {
 	int ret = 0;
 	uint32_t insn = UNALIGNED_GET((uint32_t *)loc);
 	uint32_t value;
+	const uintptr_t load_bias = llext_text_start(ext);
+
+	ARG_UNUSED(ldr);
+	ARG_UNUSED(shdr);
+	ARG_UNUSED(sym);
 
 	sym_base_addr += rel->r_addend;
 

diff --git a/arch/arm/core/elf.c b/arch/arm/core/elf.c
@@ -7,6 +7,7 @@
 
 #include <zephyr/llext/elf.h>
 #include <zephyr/llext/llext.h>
+#include <zephyr/llext/llext_internal.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/sys/util.h>
 
@@ -316,11 +317,17 @@ static void thm_movs_handler(elf_word reloc_type, uint32_t loc,
  * Do NOT mix them with not 'Thumb instructions' in the below switch/case: they are not
  * intended to work together.
  */
-int arch_elf_relocate(elf_rela_t *rel, uintptr_t loc, uintptr_t sym_base_addr,
-			const char *sym_name, uintptr_t load_bias)
+int arch_elf_relocate(struct llext_loader *ldr, const struct llext *ext, elf_rela_t *rel,
+		      const elf_shdr_t *shdr, const elf_sym_t *sym, uintptr_t loc,
+		      uintptr_t sym_base_addr, const char *sym_name)
 {
 	int ret = 0;
 	elf_word reloc_type = ELF32_R_TYPE(rel->r_info);
+	const uintptr_t load_bias = llext_text_start(ext);
+
+	ARG_UNUSED(ldr);
+	ARG_UNUSED(shdr);
+	ARG_UNUSED(sym);
 
 	LOG_DBG("%d %lx %lx %s", reloc_type, loc, sym_base_addr, sym_name);
 

diff --git a/arch/arm64/core/elf.c b/arch/arm64/core/elf.c
@@ -6,6 +6,7 @@
 
 #include <zephyr/llext/elf.h>
 #include <zephyr/llext/llext.h>
+#include <zephyr/llext/llext_internal.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/sys/util.h>
 #include <zephyr/sys/byteorder.h>
@@ -430,13 +431,19 @@ static int imm_reloc_handler(elf_rela_t *rel, elf_word reloc_type, uintptr_t loc
  * @retval -ENOTSUP Unsupported relocation
  * @retval -ENOEXEC Invalid relocation
  */
-int arch_elf_relocate(elf_rela_t *rel, uintptr_t loc, uintptr_t sym_base_addr, const char *sym_name,
-		      uintptr_t load_bias)
+int arch_elf_relocate(struct llext_loader *ldr, const struct llext *ext, elf_rela_t *rel,
+		      const elf_shdr_t *shdr, const elf_sym_t *sym, uintptr_t loc,
+		      uintptr_t sym_base_addr, const char *sym_name)
 {
 	int ret = 0;
 	bool overflow_check = true;
 	elf_word reloc_type = ELF_R_TYPE(rel->r_info);
 
+	ARG_UNUSED(ext);
+	ARG_UNUSED(ldr);
+	ARG_UNUSED(shdr);
+	ARG_UNUSED(sym);
+
 	switch (reloc_type) {
 	case R_ARM_NONE:
 	case R_AARCH64_NONE:

diff --git a/arch/riscv/core/elf.c b/arch/riscv/core/elf.c
@@ -68,11 +68,13 @@ static long long last_u_type_jump_target;
  * https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-elf.adoc
  *
  */
-int arch_elf_relocate(elf_rela_t *rel, uintptr_t loc_unsigned, uintptr_t sym_base_addr_unsigned,
-		      const char *sym_name, uintptr_t load_bias)
+int arch_elf_relocate(struct llext_loader *ldr, const struct llext *ext, elf_rela_t *rel,
+		      const elf_shdr_t *shdr, const elf_sym_t *sym, uintptr_t loc_unsigned,
+		      uintptr_t sym_base_addr_unsigned, const char *sym_name)
 {
 	/* FIXME currently, RISC-V relocations all fit in ELF_32_R_TYPE */
 	elf_word reloc_type = ELF32_R_TYPE(rel->r_info);
+	const uintptr_t load_bias = llext_text_start(ext);
 	/*
 	 * The RISC-V specification uses the following symbolic names for the relocations:
 	 *
@@ -105,6 +107,10 @@ int arch_elf_relocate(elf_rela_t *rel, uintptr_t loc_unsigned, uintptr_t sym_bas
 		sym_name, (void *)loc, (void *)sym_base_addr, (void *)load_bias,
 		(uint64_t)reloc_type);
 
+	ARG_UNUSED(ldr);
+	ARG_UNUSED(shdr);
+	ARG_UNUSED(sym);
+
 	/* FIXME not all types of relocations currently supported, especially TLS */
 
 	switch (reloc_type) {

diff --git a/include/zephyr/llext/llext.h b/include/zephyr/llext/llext.h
@@ -354,18 +354,24 @@ int llext_add_domain(struct llext *ext, struct k_mem_domain *domain);
  * symbolic data such as a section, function, or object. These relocations
  * are architecture specific and each architecture supporting LLEXT must
  * implement this.
+ * Arguments sym_base_addr, sym_name can be computed from the sym parameter,
+ * but these parameters are provided redundantly to increase efficiency.
  *
+ * @param[in] ldr Extension loader
+ * @param[in] ext Extension being relocated refers to
  * @param[in] rel Relocation data provided by ELF
+ * @param[in] shdr Header of the ELF section currently being located
+ * @param[in] sym ELF symbol to be relocated
  * @param[in] loc Address of opcode to rewrite
  * @param[in] sym_base_addr Address of symbol referenced by relocation
  * @param[in] sym_name Name of symbol referenced by relocation
- * @param[in] load_bias `.text` load address
  * @retval 0 Success
  * @retval -ENOTSUP Unsupported relocation
  * @retval -ENOEXEC Invalid relocation
  */
-int arch_elf_relocate(elf_rela_t *rel, uintptr_t loc,
-			     uintptr_t sym_base_addr, const char *sym_name, uintptr_t load_bias);
+int arch_elf_relocate(struct llext_loader *ldr, const struct llext *ext, elf_rela_t *rel,
+		      const elf_shdr_t *shdr, const elf_sym_t *sym, uintptr_t loc,
+		      uintptr_t sym_base_addr, const char *sym_name);
 
 /**
  * @brief Locates an ELF section in the file.

diff --git a/include/zephyr/llext/llext_internal.h b/include/zephyr/llext/llext_internal.h
@@ -28,6 +28,11 @@ struct llext_elf_sect_map {
 
 const void *llext_loaded_sect_ptr(struct llext_loader *ldr, struct llext *ext, unsigned int sh_ndx);
 
+static inline uintptr_t llext_text_start(const struct llext *ext)
+{
+	return (uintptr_t)ext->mem[LLEXT_MEM_TEXT];
+}
+
 /** @endcond */
 
 #ifdef __cplusplus

diff --git a/subsys/llext/llext_link.c b/subsys/llext/llext_link.c
@@ -26,8 +26,9 @@ LOG_MODULE_DECLARE(llext, CONFIG_LLEXT_LOG_LEVEL);
 #define SYM_NAME_OR_SLID(name, slid) name
 #endif
 
-__weak int arch_elf_relocate(elf_rela_t *rel, uintptr_t loc,
-			     uintptr_t sym_base_addr, const char *sym_name, uintptr_t load_bias)
+__weak int arch_elf_relocate(struct llext_loader *ldr, const struct llext *ext, elf_rela_t *rel,
+			     const elf_shdr_t *shdr, const elf_sym_t *sym, uintptr_t loc,
+			     uintptr_t sym_base_addr, const char *sym_name)
 {
 	return -ENOTSUP;
 }
@@ -142,20 +143,10 @@ static const void *llext_find_extension_sym(const char *sym_name, struct llext *
 	return se.addr;
 }
 
-/**
- * @brief Determine address of a symbol.
- *
- * @param ext llext extension
- * @param ldr llext loader
- * @param link_addr (output) resolved address
- * @param rel relocation entry
- * @param sym symbol entry
- * @param name symbol name
- * @param shdr section header
- *
- * @return 0 for OK, negative for error
+/*
+ * Determine address of a symbol.
  */
-static int llext_lookup_symbol(struct llext *ext, struct llext_loader *ldr, uintptr_t *link_addr,
+static int llext_lookup_symbol(struct llext_loader *ldr, struct llext *ext, uintptr_t *link_addr,
 			       const elf_rela_t *rel, const elf_sym_t *sym, const char *name,
 			       const elf_shdr_t *shdr)
 {
@@ -219,7 +210,6 @@ static int llext_lookup_symbol(struct llext *ext, struct llext_loader *ldr, uint
 	return 0;
 }
 
-
 static void llext_link_plt(struct llext_loader *ldr, struct llext *ext, elf_shdr_t *shdr,
 			   const struct llext_load_param *ldr_parm, elf_shdr_t *tgt)
 {
@@ -485,7 +475,7 @@ int llext_link(struct llext_loader *ldr, struct llext *ext, const struct llext_l
 
 			op_loc = sect_base + rel.r_offset;
 
-			ret = llext_lookup_symbol(ext, ldr, &link_addr, &rel, &sym, name, shdr);
+			ret = llext_lookup_symbol(ldr, ext, &link_addr, &rel, &sym, name, shdr);
 
 			if (ret != 0) {
 				LOG_ERR("Failed to lookup symbol in rela section %d entry %d!", i,
@@ -499,8 +489,8 @@ int llext_link(struct llext_loader *ldr, struct llext *ext, const struct llext_l
 				op_loc, link_addr);
 
 			/* relocation */
-			ret = arch_elf_relocate(&rel, op_loc, link_addr, name,
-					     (uintptr_t)ext->mem[LLEXT_MEM_TEXT]);
+			ret = arch_elf_relocate(ldr, ext, &rel, shdr, &sym, op_loc, link_addr,
+						name);
 			if (ret != 0) {
 				return ret;
 			}