Add all final module relocations and add error logs explaining the ones
that are not supported. Implement overflow checks for
ADD/SUB/SET/ULEB128 relocations.
Signed-off-by: Charlie Jenkins <charlie@xxxxxxxxxxxx>
---
arch/riscv/include/uapi/asm/elf.h | 5 +-
arch/riscv/kernel/module.c | 448 +++++++++++++++++++++++++++++++++++---
2 files changed, 423 insertions(+), 30 deletions(-)
diff --git a/arch/riscv/include/uapi/asm/elf.h b/arch/riscv/include/uapi/asm/elf.h
index d696d6610231..11a71b8533d5 100644
--- a/arch/riscv/include/uapi/asm/elf.h
+++ b/arch/riscv/include/uapi/asm/elf.h
@@ -49,6 +49,7 @@ typedef union __riscv_fp_state elf_fpregset_t;
#define R_RISCV_TLS_DTPREL64 9
#define R_RISCV_TLS_TPREL32 10
#define R_RISCV_TLS_TPREL64 11
+#define R_RISCV_IRELATIVE 58
/* Relocation types not used by the dynamic linker */
#define R_RISCV_BRANCH 16
@@ -81,7 +82,6 @@ typedef union __riscv_fp_state elf_fpregset_t;
#define R_RISCV_ALIGN 43
#define R_RISCV_RVC_BRANCH 44
#define R_RISCV_RVC_JUMP 45
-#define R_RISCV_LUI 46
#define R_RISCV_GPREL_I 47
#define R_RISCV_GPREL_S 48
#define R_RISCV_TPREL_I 49
@@ -93,6 +93,9 @@ typedef union __riscv_fp_state elf_fpregset_t;
#define R_RISCV_SET16 55
#define R_RISCV_SET32 56
#define R_RISCV_32_PCREL 57
+#define R_RISCV_PLT32 59
+#define R_RISCV_SET_ULEB128 60
+#define R_RISCV_SUB_ULEB128 61
#endif /* _UAPI_ASM_RISCV_ELF_H */
diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c
index 8286d3bb04f4..4b339729d5ec 100644
--- a/arch/riscv/kernel/module.c
+++ b/arch/riscv/kernel/module.c
@@ -7,6 +7,9 @@
#include <linux/elf.h>
#include <linux/err.h>
#include <linux/errno.h>
+#include <linux/hashtable.h>
+#include <linux/kernel.h>
+#include <linux/log2.h>
#include <linux/moduleloader.h>
#include <linux/vmalloc.h>
#include <linux/sizes.h>
@@ -14,6 +17,38 @@
#include <asm/alternative.h>
#include <asm/sections.h>
+struct used_bucket {
+ struct list_head head;
+ struct hlist_head *bucket;
+};
+
+struct relocation_head {
+ struct hlist_node node;
+ struct list_head *rel_entry;
+ void *location;
+};
+
+struct relocation_entry {
+ struct list_head head;
+ Elf_Addr value;
+ unsigned int type;
+};
+
+struct relocation_handlers {
+ int (*reloc_handler)(struct module *me, void *location, Elf_Addr v);
+ int (*accumulate_handler)(struct module *me, void *location,
+ long buffer);
+};
+
+unsigned int initialize_relocation_hashtable(unsigned int num_relocations);
+void process_accumulated_relocations(struct module *me);
+int add_relocation_to_accumulate(struct module *me, int type, void *location,
+ unsigned int hashtable_bits, Elf_Addr v);
+
+struct hlist_head *relocation_hashtable;
+
+struct list_head used_buckets_list;
+
/*
* The auipc+jalr instruction pair can reach any PC-relative offset
* in the range [-2^31 - 2^11, 2^31 - 2^11)
@@ -273,6 +308,12 @@ static int apply_r_riscv_align_rela(struct module *me, void *location,
return -EINVAL;
}
+static int apply_r_riscv_add8_rela(struct module *me, void *location, Elf_Addr v)
+{
+ *(u8 *)location += (u8)v;
+ return 0;
+}
+
static int apply_r_riscv_add16_rela(struct module *me, void *location,
Elf_Addr v)
{
@@ -294,6 +335,12 @@ static int apply_r_riscv_add64_rela(struct module *me, void *location,
return 0;
}
+static int apply_r_riscv_sub8_rela(struct module *me, void *location, Elf_Addr v)
+{
+ *(u8 *)location -= (u8)v;
+ return 0;
+}
+
static int apply_r_riscv_sub16_rela(struct module *me, void *location,
Elf_Addr v)
{
@@ -315,33 +362,369 @@ static int apply_r_riscv_sub64_rela(struct module *me, void *location,
return 0;
}
-static int (*reloc_handlers_rela[]) (struct module *me, void *location,
- Elf_Addr v) = {
- [R_RISCV_32] = apply_r_riscv_32_rela,
- [R_RISCV_64] = apply_r_riscv_64_rela,
- [R_RISCV_BRANCH] = apply_r_riscv_branch_rela,
- [R_RISCV_JAL] = apply_r_riscv_jal_rela,
- [R_RISCV_RVC_BRANCH] = apply_r_riscv_rvc_branch_rela,
- [R_RISCV_RVC_JUMP] = apply_r_riscv_rvc_jump_rela,
- [R_RISCV_PCREL_HI20] = apply_r_riscv_pcrel_hi20_rela,
- [R_RISCV_PCREL_LO12_I] = apply_r_riscv_pcrel_lo12_i_rela,
- [R_RISCV_PCREL_LO12_S] = apply_r_riscv_pcrel_lo12_s_rela,
- [R_RISCV_HI20] = apply_r_riscv_hi20_rela,
- [R_RISCV_LO12_I] = apply_r_riscv_lo12_i_rela,
- [R_RISCV_LO12_S] = apply_r_riscv_lo12_s_rela,
- [R_RISCV_GOT_HI20] = apply_r_riscv_got_hi20_rela,
- [R_RISCV_CALL_PLT] = apply_r_riscv_call_plt_rela,
- [R_RISCV_CALL] = apply_r_riscv_call_rela,
- [R_RISCV_RELAX] = apply_r_riscv_relax_rela,
- [R_RISCV_ALIGN] = apply_r_riscv_align_rela,
- [R_RISCV_ADD16] = apply_r_riscv_add16_rela,
- [R_RISCV_ADD32] = apply_r_riscv_add32_rela,
- [R_RISCV_ADD64] = apply_r_riscv_add64_rela,
- [R_RISCV_SUB16] = apply_r_riscv_sub16_rela,
- [R_RISCV_SUB32] = apply_r_riscv_sub32_rela,
- [R_RISCV_SUB64] = apply_r_riscv_sub64_rela,
+static int dynamic_linking_not_supported(struct module *me, void *location,
+ Elf_Addr v)
+{
+ pr_err("%s: Dynamic linking not supported in kernel modules PC = %p\n",
+ me->name, location);
+ return -EINVAL;
+}
+
+static int tls_not_supported(struct module *me, void *location, Elf_Addr v)
+{
+ pr_err("%s: Thread local storage not supported in kernel modules PC = %p\n",
+ me->name, location);
+ return -EINVAL;
+}
+
+static int apply_r_riscv_sub6_rela(struct module *me, void *location, Elf_Addr v)
+{
+ u8 *byte = location;
+ u8 value = v;
+
+ *byte = (*byte - (value & 0x3f)) & 0x3f;
+ return 0;
+}
+
+static int apply_r_riscv_set6_rela(struct module *me, void *location, Elf_Addr v)
+{
+ u8 *byte = location;
+ u8 value = v;
+
+ *byte = (*byte & 0xc0) | (value & 0x3f);
+ return 0;
+}
+
+static int apply_r_riscv_set8_rela(struct module *me, void *location, Elf_Addr v)
+{
+ *(u8 *)location = (u8)v;
+ return 0;
+}
+
+static int apply_r_riscv_set16_rela(struct module *me, void *location,
+ Elf_Addr v)
+{
+ *(u16 *)location = (u16)v;
+ return 0;
+}
+
+static int apply_r_riscv_set32_rela(struct module *me, void *location,
+ Elf_Addr v)
+{
+ *(u32 *)location = (u32)v;
+ return 0;
+}
+
+static int apply_r_riscv_32_pcrel_rela(struct module *me, void *location,
+ Elf_Addr v)
+{
+ *(u32 *)location = v - (uintptr_t)location;
+ return 0;
+}
+
+static int apply_r_riscv_plt32_rela(struct module *me, void *location,
+ Elf_Addr v)
+{
+ ptrdiff_t offset = (void *)v - location;
+
+ if (!riscv_insn_valid_32bit_offset(offset)) {
+ /* Only emit the plt entry if offset over 32-bit range */
+ if (IS_ENABLED(CONFIG_MODULE_SECTIONS)) {
+ offset = (void *)module_emit_plt_entry(me, v) - location;
+ } else {
+ pr_err("%s: target %016llx can not be addressed by the 32-bit offset from PC = %p\n",
+ me->name, (long long)v, location);
+ return -EINVAL;
+ }
+ }
+
+ *(u32 *)location = (u32)offset;
+ return 0;
+}
+
+static int apply_r_riscv_set_uleb128(struct module *me, void *location, Elf_Addr v)
+{
+ *(long *)location = v;
+ return 0;
+}
+
+static int apply_r_riscv_sub_uleb128(struct module *me, void *location, Elf_Addr v)
+{
+ *(long *)location -= v;
+ return 0;
+}
+
+static int apply_6_bit_accumulation(struct module *me, void *location, long buffer)
+{
+ u8 *byte = location;
+ u8 value = buffer;
+
+ if (buffer > 0x3f) {
+ pr_err("%s: value %ld out of range for 6-bit relocation.\n",
+ me->name, buffer);
+ return -EINVAL;
+ }
+
+ *byte = (*byte & 0xc0) | (value & 0x3f);
+ return 0;
+}
+
+static int apply_8_bit_accumulation(struct module *me, void *location, long buffer)
+{
+ if (buffer > U8_MAX) {
+ pr_err("%s: value %ld out of range for 8-bit relocation.\n",
+ me->name, buffer);
+ return -EINVAL;
+ }
+ *(u8 *)location = (u8)buffer;
+ return 0;
+}
+
+static int apply_16_bit_accumulation(struct module *me, void *location, long buffer)
+{
+ if (buffer > U16_MAX) {
+ pr_err("%s: value %ld out of range for 16-bit relocation.\n",
+ me->name, buffer);
+ return -EINVAL;
+ }
+ *(u16 *)location = (u16)buffer;
+ return 0;
+}
+
+static int apply_32_bit_accumulation(struct module *me, void *location, long buffer)
+{
+ if (buffer > U32_MAX) {
+ pr_err("%s: value %ld out of range for 32-bit relocation.\n",
+ me->name, buffer);
+ return -EINVAL;
+ }
+ *(u32 *)location = (u32)buffer;
+ return 0;
+}
+
+static int apply_64_bit_accumulation(struct module *me, void *location, long buffer)
+{
+ *(u64 *)location = (u64)buffer;
+ return 0;
+}
+
+static int apply_uleb128_accumulation(struct module *me, void *location, long buffer)
+{
+ /*
+ * ULEB128 is a variable length encoding. Encode the buffer into
+ * the ULEB128 data format.
+ */
+ u8 *p = location;
+
+ while (buffer != 0) {
+ u8 value = buffer & 0x7f;
+
+ buffer >>= 7;
+ value |= (!!buffer) << 7;
+
+ *p++ = value;
+ }
+ return 0;
+}
+
+/*
+ * Relocations defined in the riscv-elf-psabi-doc.
+ * This handles static linking only.
+ */
+static const struct relocation_handlers reloc_handlers[] = {
+ [R_RISCV_32] = { apply_r_riscv_32_rela },
+ [R_RISCV_64] = { apply_r_riscv_64_rela },
+ [R_RISCV_RELATIVE] = { dynamic_linking_not_supported },
+ [R_RISCV_COPY] = { dynamic_linking_not_supported },
+ [R_RISCV_JUMP_SLOT] = { dynamic_linking_not_supported },
+ [R_RISCV_TLS_DTPMOD32] = { dynamic_linking_not_supported },
+ [R_RISCV_TLS_DTPMOD64] = { dynamic_linking_not_supported },
+ [R_RISCV_TLS_DTPREL32] = { dynamic_linking_not_supported },
+ [R_RISCV_TLS_DTPREL64] = { dynamic_linking_not_supported },
+ [R_RISCV_TLS_TPREL32] = { dynamic_linking_not_supported },
+ [R_RISCV_TLS_TPREL64] = { dynamic_linking_not_supported },
+ /* 12-15 undefined */
+ [R_RISCV_BRANCH] = { apply_r_riscv_branch_rela },
+ [R_RISCV_JAL] = { apply_r_riscv_jal_rela },
+ [R_RISCV_CALL] = { apply_r_riscv_call_rela },
+ [R_RISCV_CALL_PLT] = { apply_r_riscv_call_plt_rela },
+ [R_RISCV_GOT_HI20] = { apply_r_riscv_got_hi20_rela },
+ [R_RISCV_TLS_GOT_HI20] = { tls_not_supported },
+ [R_RISCV_TLS_GD_HI20] = { tls_not_supported },
+ [R_RISCV_PCREL_HI20] = { apply_r_riscv_pcrel_hi20_rela },
+ [R_RISCV_PCREL_LO12_I] = { apply_r_riscv_pcrel_lo12_i_rela },
+ [R_RISCV_PCREL_LO12_S] = { apply_r_riscv_pcrel_lo12_s_rela },
+ [R_RISCV_HI20] = { apply_r_riscv_hi20_rela },
+ [R_RISCV_LO12_I] = { apply_r_riscv_lo12_i_rela },
+ [R_RISCV_LO12_S] = { apply_r_riscv_lo12_s_rela },
+ [R_RISCV_TPREL_HI20] = { tls_not_supported },
+ [R_RISCV_TPREL_LO12_I] = { tls_not_supported },
+ [R_RISCV_TPREL_LO12_S] = { tls_not_supported },
+ [R_RISCV_TPREL_ADD] = { tls_not_supported },
+ [R_RISCV_ADD8] = { apply_r_riscv_add8_rela, apply_8_bit_accumulation },
+ [R_RISCV_ADD16] = { apply_r_riscv_add16_rela,
+ apply_16_bit_accumulation },
+ [R_RISCV_ADD32] = { apply_r_riscv_add32_rela,
+ apply_32_bit_accumulation },
+ [R_RISCV_ADD64] = { apply_r_riscv_add64_rela,
+ apply_64_bit_accumulation },
+ [R_RISCV_SUB8] = { apply_r_riscv_sub8_rela, apply_8_bit_accumulation },
+ [R_RISCV_SUB16] = { apply_r_riscv_sub16_rela,
+ apply_16_bit_accumulation },
+ [R_RISCV_SUB32] = { apply_r_riscv_sub32_rela,
+ apply_32_bit_accumulation },
+ [R_RISCV_SUB64] = { apply_r_riscv_sub64_rela,
+ apply_64_bit_accumulation },
+ /* 41-42 reserved for future standard use */
+ [R_RISCV_ALIGN] = { apply_r_riscv_align_rela },
+ [R_RISCV_RVC_BRANCH] = { apply_r_riscv_rvc_branch_rela },
+ [R_RISCV_RVC_JUMP] = { apply_r_riscv_rvc_jump_rela },
+ /* 46-50 reserved for future standard use */
+ [R_RISCV_RELAX] = { apply_r_riscv_relax_rela },
+ [R_RISCV_SUB6] = { apply_r_riscv_sub6_rela, apply_6_bit_accumulation },
+ [R_RISCV_SET6] = { apply_r_riscv_set6_rela, apply_6_bit_accumulation },
+ [R_RISCV_SET8] = { apply_r_riscv_set8_rela, apply_8_bit_accumulation },
+ [R_RISCV_SET16] = { apply_r_riscv_set16_rela,
+ apply_16_bit_accumulation },
+ [R_RISCV_SET32] = { apply_r_riscv_set32_rela,
+ apply_32_bit_accumulation },
+ [R_RISCV_32_PCREL] = { apply_r_riscv_32_pcrel_rela },
+ [R_RISCV_IRELATIVE] = { dynamic_linking_not_supported },
+ [R_RISCV_PLT32] = { apply_r_riscv_plt32_rela },
+ [R_RISCV_SET_ULEB128] = { apply_r_riscv_set_uleb128,
+ apply_uleb128_accumulation },
+ [R_RISCV_SUB_ULEB128] = { apply_r_riscv_sub_uleb128,
+ apply_uleb128_accumulation },
+ /* 62-191 reserved for future standard use */
+ /* 192-255 nonstandard ABI extensions */
};
+void process_accumulated_relocations(struct module *me)
+{
+ /*
+ * Only ADD/SUB/SET/ULEB128 should end up here.
+ *
+ * Each bucket may have more than one relocation location. All
+ * relocations for a location are stored in a list in a bucket.
+ *
+ * Relocations are applied to a temp variable before being stored to the
+ * provided location to check for overflow. This also allows ULEB128 to
+ * properly decide how many entries are needed before storing to
+ * location. The final value is stored into location using the handler
+ * for the last relocation to an address.
+ *
+ * Three layers of indexing:
+ * - Each of the buckets in use
+ * - Groups of relocations in each bucket by location address
+ * - Each relocation entry for a location address
+ */
+ struct used_bucket *bucket_iter;
+ struct relocation_head *rel_head_iter;
+ struct relocation_entry *rel_entry_iter;
+ int curr_type;
+ void *location;
+ long buffer;
+
+ list_for_each_entry(bucket_iter, &used_buckets_list, head) {
+ hlist_for_each_entry(rel_head_iter, bucket_iter->bucket, node) {
+ buffer = 0;
+ location = rel_head_iter->location;
+ list_for_each_entry(rel_entry_iter,
+ rel_head_iter->rel_entry, head) {
+ curr_type = rel_entry_iter->type;
+ reloc_handlers[curr_type].reloc_handler(
+ me, &buffer, rel_entry_iter->value);
+ kfree(rel_entry_iter);
+ }
+ reloc_handlers[curr_type].accumulate_handler(
+ me, location, buffer);
+ kfree(rel_head_iter);
+ }
+ kfree(bucket_iter);
+ }
+
+ kfree(relocation_hashtable);
+}
+
+int add_relocation_to_accumulate(struct module *me, int type, void *location,
+ unsigned int hashtable_bits, Elf_Addr v)
+{
+ struct relocation_entry *entry;
+ struct relocation_head *rel_head;
+ struct hlist_head *current_head;
+ struct used_bucket *bucket;
+ unsigned long hash;
+
+ entry = kmalloc(sizeof(*entry), GFP_KERNEL);
+ INIT_LIST_HEAD(&entry->head);
+ entry->type = type;
+ entry->value = v;
+
+ hash = hash_min((uintptr_t)location, hashtable_bits);
+
+ current_head = &relocation_hashtable[hash];
+
+ /* Find matching location (if any) */
+ bool found = false;
+ struct relocation_head *rel_head_iter;
+
+ hlist_for_each_entry(rel_head_iter, current_head, node) {
+ if (rel_head_iter->location == location) {
+ found = true;
+ rel_head = rel_head_iter;
+ break;
+ }
+ }
+
+ if (!found) {
+ rel_head = kmalloc(sizeof(*rel_head), GFP_KERNEL);
+ rel_head->rel_entry =
+ kmalloc(sizeof(struct list_head), GFP_KERNEL);
+ INIT_LIST_HEAD(rel_head->rel_entry);
+ rel_head->location = location;
+ INIT_HLIST_NODE(&rel_head->node);
+ if (!current_head->first) {
+ bucket =
+ kmalloc(sizeof(struct used_bucket), GFP_KERNEL);
+ INIT_LIST_HEAD(&bucket->head);
+ bucket->bucket = current_head;
+ list_add(&bucket->head, &used_buckets_list);
+ }
+ hlist_add_head(&rel_head->node, current_head);
+ }
+
+ /* Add relocation to head of discovered rel_head */
+ list_add_tail(&entry->head, rel_head->rel_entry);
+
+ return 0;
+}
+
+unsigned int initialize_relocation_hashtable(unsigned int num_relocations)
+{
+ /* Can safely assume that bits is not greater than sizeof(long) */
+ unsigned long hashtable_size = roundup_pow_of_two(num_relocations);
+ unsigned int hashtable_bits = ilog2(hashtable_size);
+
+ /*
+ * Double size of hashtable if num_relocations * 1.25 is greater than
+ * hashtable_size.
+ */
+ int should_double_size = ((num_relocations + (num_relocations >> 2)) > (hashtable_size));
+
+ hashtable_bits += should_double_size;
+
+ hashtable_size <<= should_double_size;
+
+ relocation_hashtable = kmalloc_array(hashtable_size,
+ sizeof(*relocation_hashtable),
+ GFP_KERNEL);
+ __hash_init(relocation_hashtable, hashtable_size);
+
+ INIT_LIST_HEAD(&used_buckets_list);
+
+ return hashtable_bits;
+}
+
int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
unsigned int symindex, unsigned int relsec,
struct module *me)
@@ -353,11 +736,13 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
unsigned int i, type;
Elf_Addr v;
int res;
+ unsigned int num_relocations = sechdrs[relsec].sh_size / sizeof(*rel);
+ unsigned int hashtable_bits = initialize_relocation_hashtable(num_relocations);
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++) {
+ for (i = 0; i < num_relocations; i++) {
/* This is where to make the change */
location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
+ rel[i].r_offset;
@@ -375,8 +760,8 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
type = ELF_RISCV_R_TYPE(rel[i].r_info);
- if (type < ARRAY_SIZE(reloc_handlers_rela))
- handler = reloc_handlers_rela[type];
+ if (type < ARRAY_SIZE(reloc_handlers))
+ handler = reloc_handlers[type].reloc_handler;
else
handler = NULL;
@@ -432,11 +817,16 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
}
}
- res = handler(me, location, v);
+ if (reloc_handlers[type].accumulate_handler)
+ res = add_relocation_to_accumulate(me, type, location, hashtable_bits, v);
+ else
+ res = handler(me, location, v);
if (res)
return res;
}
+ process_accumulated_relocations(me);
+
return 0;
}
--
2.34.1
