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 <[email protected]>
---
arch/riscv/include/uapi/asm/elf.h | 5 +-
arch/riscv/kernel/module.c | 503 +++++++++++++++++++++++++++++++++++---
2 files changed, 476 insertions(+), 32 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 a9e94e939cb5..0f5d41eaa596 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 +17,39 @@
#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);
+ bool accumulate_relocations;
+ 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)
@@ -35,7 +71,7 @@ static int riscv_insn_rmw(void *location, u32 keep, u32 set)
insn &= keep;
insn |= set;
- parcel[0] = cpu_to_le32(insn);
+ parcel[0] = cpu_to_le16(insn);
parcel[1] = cpu_to_le16(insn >> 16);
return 0;
}
@@ -43,8 +79,12 @@ static int riscv_insn_rmw(void *location, u32 keep, u32 set)
static int riscv_insn_rvc_rmw(void *location, u16 keep, u16 set)
{
u16 *parcel = location;
+ u16 insn = le16_to_cpu(*parcel);
- *parcel = cpu_to_le16((le16_to_cpu(*parcel) & keep) | set);
+ insn &= keep;
+ insn |= set;
+
+ *parcel = cpu_to_le16(insn);
return 0;
}
@@ -269,6 +309,12 @@ 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)
{
@@ -290,6 +336,12 @@ 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)
{
@@ -311,33 +363,415 @@ 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 - (unsigned long)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 accumulation_not_supported(struct module *me, void *location, long buffer)
+{
+ pr_err("%s: Internal error. Only ADD/SUB/SET/ULEB128 should be accumulated.", me->name);
+ return -EINVAL;
+}
+
+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 struct relocation_handlers reloc_handlers[] = {
+ [R_RISCV_32] = { apply_r_riscv_32_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_64] = { apply_r_riscv_64_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_RELATIVE] = { dynamic_linking_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_COPY] = { dynamic_linking_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_JUMP_SLOT] = { dynamic_linking_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_TLS_DTPMOD32] = { dynamic_linking_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_TLS_DTPMOD64] = { dynamic_linking_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_TLS_DTPREL32] = { dynamic_linking_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_TLS_DTPREL64] = { dynamic_linking_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_TLS_TPREL32] = { dynamic_linking_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_TLS_TPREL64] = { dynamic_linking_not_supported, false,
+ accumulation_not_supported },
+ /* 12-15 undefined */
+ [R_RISCV_BRANCH] = { apply_r_riscv_branch_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_JAL] = { apply_r_riscv_jal_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_CALL] = { apply_r_riscv_call_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_CALL_PLT] = { apply_r_riscv_call_plt_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_GOT_HI20] = { apply_r_riscv_got_hi20_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_TLS_GOT_HI20] = { tls_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_TLS_GD_HI20] = { tls_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_PCREL_HI20] = { apply_r_riscv_pcrel_hi20_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_PCREL_LO12_I] = { apply_r_riscv_pcrel_lo12_i_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_PCREL_LO12_S] = { apply_r_riscv_pcrel_lo12_s_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_HI20] = { apply_r_riscv_hi20_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_LO12_I] = { apply_r_riscv_lo12_i_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_LO12_S] = { apply_r_riscv_lo12_s_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_TPREL_HI20] = { tls_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_TPREL_LO12_I] = { tls_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_TPREL_LO12_S] = { tls_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_TPREL_ADD] = { tls_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_ADD8] = { apply_r_riscv_add8_rela, true,
+ apply_8_bit_accumulation },
+ [R_RISCV_ADD16] = { apply_r_riscv_add16_rela, true,
+ apply_16_bit_accumulation },
+ [R_RISCV_ADD32] = { apply_r_riscv_add32_rela, true,
+ apply_32_bit_accumulation },
+ [R_RISCV_ADD64] = { apply_r_riscv_add64_rela, true,
+ apply_64_bit_accumulation },
+ [R_RISCV_SUB8] = { apply_r_riscv_sub8_rela, true,
+ apply_8_bit_accumulation },
+ [R_RISCV_SUB16] = { apply_r_riscv_sub16_rela, true,
+ apply_16_bit_accumulation },
+ [R_RISCV_SUB32] = { apply_r_riscv_sub32_rela, true,
+ apply_32_bit_accumulation },
+ [R_RISCV_SUB64] = { apply_r_riscv_sub64_rela, true,
+ apply_64_bit_accumulation },
+ /* 41-42 reserved for future standard use */
+ [R_RISCV_ALIGN] = { apply_r_riscv_align_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_RVC_BRANCH] = { apply_r_riscv_rvc_branch_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_RVC_JUMP] = { apply_r_riscv_rvc_jump_rela, false,
+ accumulation_not_supported },
+ /* 46-50 reserved for future standard use */
+ [R_RISCV_RELAX] = { apply_r_riscv_relax_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_SUB6] = { apply_r_riscv_sub6_rela, true,
+ apply_6_bit_accumulation },
+ [R_RISCV_SET6] = { apply_r_riscv_set6_rela, true,
+ apply_6_bit_accumulation },
+ [R_RISCV_SET8] = { apply_r_riscv_set8_rela, true,
+ apply_8_bit_accumulation },
+ [R_RISCV_SET16] = { apply_r_riscv_set16_rela, true,
+ apply_16_bit_accumulation },
+ [R_RISCV_SET32] = { apply_r_riscv_set32_rela, true,
+ apply_32_bit_accumulation },
+ [R_RISCV_32_PCREL] = { apply_r_riscv_32_pcrel_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_IRELATIVE] = { dynamic_linking_not_supported, false,
+ accumulation_not_supported },
+ [R_RISCV_PLT32] = { apply_r_riscv_plt32_rela, false,
+ accumulation_not_supported },
+ [R_RISCV_SET_ULEB128] = { apply_r_riscv_set_uleb128, true,
+ apply_uleb128_accumulation },
+ [R_RISCV_SUB_ULEB128] = { apply_r_riscv_sub_uleb128, true,
+ 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((unsigned long)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)
@@ -349,11 +783,13 @@ 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;
@@ -371,8 +807,8 @@ 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;
@@ -428,11 +864,16 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
}
}
- res = handler(me, location, v);
+ if (reloc_handlers[type].accumulate_relocations)
+ 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
Charlie Jenkins wrote:
> 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 <[email protected]>
> ---
> arch/riscv/include/uapi/asm/elf.h | 5 +-
> arch/riscv/kernel/module.c | 503 +++++++++++++++++++++++++++++++++++---
> 2 files changed, 476 insertions(+), 32 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 a9e94e939cb5..0f5d41eaa596 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 +17,39 @@
> #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);
> + bool accumulate_relocations;
> + 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)
> @@ -35,7 +71,7 @@ static int riscv_insn_rmw(void *location, u32 keep, u32 set)
> insn &= keep;
> insn |= set;
>
> - parcel[0] = cpu_to_le32(insn);
> + parcel[0] = cpu_to_le16(insn);
> parcel[1] = cpu_to_le16(insn >> 16);
> return 0;
> }
> @@ -43,8 +79,12 @@ static int riscv_insn_rmw(void *location, u32 keep, u32 set)
> static int riscv_insn_rvc_rmw(void *location, u16 keep, u16 set)
> {
> u16 *parcel = location;
> + u16 insn = le16_to_cpu(*parcel);
>
> - *parcel = cpu_to_le16((le16_to_cpu(*parcel) & keep) | set);
> + insn &= keep;
> + insn |= set;
> +
> + *parcel = cpu_to_le16(insn);
> return 0;
> }
I think you meant to squash these two chunks into the previous patch.
>
> @@ -269,6 +309,12 @@ 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)
> {
> @@ -290,6 +336,12 @@ 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)
> {
> @@ -311,33 +363,415 @@ 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 - (unsigned long)location;
nit: in other reviews i've been told to use uintptr_t when casting pointers to
an unsigned integer.
> + 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 accumulation_not_supported(struct module *me, void *location, long buffer)
> +{
> + pr_err("%s: Internal error. Only ADD/SUB/SET/ULEB128 should be accumulated.", me->name);
> + return -EINVAL;
> +}
> +
> +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 struct relocation_handlers reloc_handlers[] = {
I don't see anywhere this table is written to. Can we maybe make it const?
> + [R_RISCV_32] = { apply_r_riscv_32_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_64] = { apply_r_riscv_64_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_RELATIVE] = { dynamic_linking_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_COPY] = { dynamic_linking_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_JUMP_SLOT] = { dynamic_linking_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_TLS_DTPMOD32] = { dynamic_linking_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_TLS_DTPMOD64] = { dynamic_linking_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_TLS_DTPREL32] = { dynamic_linking_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_TLS_DTPREL64] = { dynamic_linking_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_TLS_TPREL32] = { dynamic_linking_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_TLS_TPREL64] = { dynamic_linking_not_supported, false,
> + accumulation_not_supported },
> + /* 12-15 undefined */
> + [R_RISCV_BRANCH] = { apply_r_riscv_branch_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_JAL] = { apply_r_riscv_jal_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_CALL] = { apply_r_riscv_call_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_CALL_PLT] = { apply_r_riscv_call_plt_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_GOT_HI20] = { apply_r_riscv_got_hi20_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_TLS_GOT_HI20] = { tls_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_TLS_GD_HI20] = { tls_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_PCREL_HI20] = { apply_r_riscv_pcrel_hi20_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_PCREL_LO12_I] = { apply_r_riscv_pcrel_lo12_i_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_PCREL_LO12_S] = { apply_r_riscv_pcrel_lo12_s_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_HI20] = { apply_r_riscv_hi20_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_LO12_I] = { apply_r_riscv_lo12_i_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_LO12_S] = { apply_r_riscv_lo12_s_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_TPREL_HI20] = { tls_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_TPREL_LO12_I] = { tls_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_TPREL_LO12_S] = { tls_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_TPREL_ADD] = { tls_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_ADD8] = { apply_r_riscv_add8_rela, true,
> + apply_8_bit_accumulation },
> + [R_RISCV_ADD16] = { apply_r_riscv_add16_rela, true,
> + apply_16_bit_accumulation },
> + [R_RISCV_ADD32] = { apply_r_riscv_add32_rela, true,
> + apply_32_bit_accumulation },
> + [R_RISCV_ADD64] = { apply_r_riscv_add64_rela, true,
> + apply_64_bit_accumulation },
> + [R_RISCV_SUB8] = { apply_r_riscv_sub8_rela, true,
> + apply_8_bit_accumulation },
> + [R_RISCV_SUB16] = { apply_r_riscv_sub16_rela, true,
> + apply_16_bit_accumulation },
> + [R_RISCV_SUB32] = { apply_r_riscv_sub32_rela, true,
> + apply_32_bit_accumulation },
> + [R_RISCV_SUB64] = { apply_r_riscv_sub64_rela, true,
> + apply_64_bit_accumulation },
> + /* 41-42 reserved for future standard use */
> + [R_RISCV_ALIGN] = { apply_r_riscv_align_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_RVC_BRANCH] = { apply_r_riscv_rvc_branch_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_RVC_JUMP] = { apply_r_riscv_rvc_jump_rela, false,
> + accumulation_not_supported },
> + /* 46-50 reserved for future standard use */
> + [R_RISCV_RELAX] = { apply_r_riscv_relax_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_SUB6] = { apply_r_riscv_sub6_rela, true,
> + apply_6_bit_accumulation },
> + [R_RISCV_SET6] = { apply_r_riscv_set6_rela, true,
> + apply_6_bit_accumulation },
> + [R_RISCV_SET8] = { apply_r_riscv_set8_rela, true,
> + apply_8_bit_accumulation },
> + [R_RISCV_SET16] = { apply_r_riscv_set16_rela, true,
> + apply_16_bit_accumulation },
> + [R_RISCV_SET32] = { apply_r_riscv_set32_rela, true,
> + apply_32_bit_accumulation },
> + [R_RISCV_32_PCREL] = { apply_r_riscv_32_pcrel_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_IRELATIVE] = { dynamic_linking_not_supported, false,
> + accumulation_not_supported },
> + [R_RISCV_PLT32] = { apply_r_riscv_plt32_rela, false,
> + accumulation_not_supported },
> + [R_RISCV_SET_ULEB128] = { apply_r_riscv_set_uleb128, true,
> + apply_uleb128_accumulation },
> + [R_RISCV_SUB_ULEB128] = { apply_r_riscv_sub_uleb128, true,
> + 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((unsigned long)location, hashtable_bits);
uintptr_t
> +
> + 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)
> @@ -349,11 +783,13 @@ 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;
> @@ -371,8 +807,8 @@ 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;
>
> @@ -428,11 +864,16 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
> }
> }
>
> - res = handler(me, location, v);
> + if (reloc_handlers[type].accumulate_relocations)
As far as I can tell the table above has accumulate_relocations == false if and
only if .accumulate_handler == accumulation_not_supported. Could we maybe drop
the bool and just check for that?
Are there situations where we might end up calling
accumulation_not_supported()? If not we could just let .accumulate_handler be
NULL where accumulation is not supported. Then the table could be initialised
with
{ reloc_handler }, // when accumulation is not supported and
{ reloc_handler, accumulate_handler }, // when it is
..and the test above would just be
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
>
>
> _______________________________________________
> linux-riscv mailing list
> [email protected]
> http://lists.infradead.org/mailman/listinfo/linux-riscv
On Wed, Nov 01, 2023 at 03:44:30PM +0100, Emil Renner Berthing wrote:
> Charlie Jenkins wrote:
> > 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 <[email protected]>
> > ---
> > arch/riscv/include/uapi/asm/elf.h | 5 +-
> > arch/riscv/kernel/module.c | 503 +++++++++++++++++++++++++++++++++++---
> > 2 files changed, 476 insertions(+), 32 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 a9e94e939cb5..0f5d41eaa596 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 +17,39 @@
> > #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);
> > + bool accumulate_relocations;
> > + 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)
> > @@ -35,7 +71,7 @@ static int riscv_insn_rmw(void *location, u32 keep, u32 set)
> > insn &= keep;
> > insn |= set;
> >
> > - parcel[0] = cpu_to_le32(insn);
> > + parcel[0] = cpu_to_le16(insn);
> > parcel[1] = cpu_to_le16(insn >> 16);
> > return 0;
> > }
> > @@ -43,8 +79,12 @@ static int riscv_insn_rmw(void *location, u32 keep, u32 set)
> > static int riscv_insn_rvc_rmw(void *location, u16 keep, u16 set)
> > {
> > u16 *parcel = location;
> > + u16 insn = le16_to_cpu(*parcel);
> >
> > - *parcel = cpu_to_le16((le16_to_cpu(*parcel) & keep) | set);
> > + insn &= keep;
> > + insn |= set;
> > +
> > + *parcel = cpu_to_le16(insn);
> > return 0;
> > }
>
> I think you meant to squash these two chunks into the previous patch.
>
> >
> > @@ -269,6 +309,12 @@ 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)
> > {
> > @@ -290,6 +336,12 @@ 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)
> > {
> > @@ -311,33 +363,415 @@ 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 - (unsigned long)location;
>
> nit: in other reviews i've been told to use uintptr_t when casting pointers to
> an unsigned integer.
>
Okay will do.
> > + 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 accumulation_not_supported(struct module *me, void *location, long buffer)
> > +{
> > + pr_err("%s: Internal error. Only ADD/SUB/SET/ULEB128 should be accumulated.", me->name);
> > + return -EINVAL;
> > +}
> > +
> > +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 struct relocation_handlers reloc_handlers[] = {
>
> I don't see anywhere this table is written to. Can we maybe make it const?
>
> > + [R_RISCV_32] = { apply_r_riscv_32_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_64] = { apply_r_riscv_64_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_RELATIVE] = { dynamic_linking_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_COPY] = { dynamic_linking_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_JUMP_SLOT] = { dynamic_linking_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TLS_DTPMOD32] = { dynamic_linking_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TLS_DTPMOD64] = { dynamic_linking_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TLS_DTPREL32] = { dynamic_linking_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TLS_DTPREL64] = { dynamic_linking_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TLS_TPREL32] = { dynamic_linking_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TLS_TPREL64] = { dynamic_linking_not_supported, false,
> > + accumulation_not_supported },
> > + /* 12-15 undefined */
> > + [R_RISCV_BRANCH] = { apply_r_riscv_branch_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_JAL] = { apply_r_riscv_jal_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_CALL] = { apply_r_riscv_call_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_CALL_PLT] = { apply_r_riscv_call_plt_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_GOT_HI20] = { apply_r_riscv_got_hi20_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TLS_GOT_HI20] = { tls_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TLS_GD_HI20] = { tls_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_PCREL_HI20] = { apply_r_riscv_pcrel_hi20_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_PCREL_LO12_I] = { apply_r_riscv_pcrel_lo12_i_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_PCREL_LO12_S] = { apply_r_riscv_pcrel_lo12_s_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_HI20] = { apply_r_riscv_hi20_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_LO12_I] = { apply_r_riscv_lo12_i_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_LO12_S] = { apply_r_riscv_lo12_s_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TPREL_HI20] = { tls_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TPREL_LO12_I] = { tls_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TPREL_LO12_S] = { tls_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_TPREL_ADD] = { tls_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_ADD8] = { apply_r_riscv_add8_rela, true,
> > + apply_8_bit_accumulation },
> > + [R_RISCV_ADD16] = { apply_r_riscv_add16_rela, true,
> > + apply_16_bit_accumulation },
> > + [R_RISCV_ADD32] = { apply_r_riscv_add32_rela, true,
> > + apply_32_bit_accumulation },
> > + [R_RISCV_ADD64] = { apply_r_riscv_add64_rela, true,
> > + apply_64_bit_accumulation },
> > + [R_RISCV_SUB8] = { apply_r_riscv_sub8_rela, true,
> > + apply_8_bit_accumulation },
> > + [R_RISCV_SUB16] = { apply_r_riscv_sub16_rela, true,
> > + apply_16_bit_accumulation },
> > + [R_RISCV_SUB32] = { apply_r_riscv_sub32_rela, true,
> > + apply_32_bit_accumulation },
> > + [R_RISCV_SUB64] = { apply_r_riscv_sub64_rela, true,
> > + apply_64_bit_accumulation },
> > + /* 41-42 reserved for future standard use */
> > + [R_RISCV_ALIGN] = { apply_r_riscv_align_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_RVC_BRANCH] = { apply_r_riscv_rvc_branch_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_RVC_JUMP] = { apply_r_riscv_rvc_jump_rela, false,
> > + accumulation_not_supported },
> > + /* 46-50 reserved for future standard use */
> > + [R_RISCV_RELAX] = { apply_r_riscv_relax_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_SUB6] = { apply_r_riscv_sub6_rela, true,
> > + apply_6_bit_accumulation },
> > + [R_RISCV_SET6] = { apply_r_riscv_set6_rela, true,
> > + apply_6_bit_accumulation },
> > + [R_RISCV_SET8] = { apply_r_riscv_set8_rela, true,
> > + apply_8_bit_accumulation },
> > + [R_RISCV_SET16] = { apply_r_riscv_set16_rela, true,
> > + apply_16_bit_accumulation },
> > + [R_RISCV_SET32] = { apply_r_riscv_set32_rela, true,
> > + apply_32_bit_accumulation },
> > + [R_RISCV_32_PCREL] = { apply_r_riscv_32_pcrel_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_IRELATIVE] = { dynamic_linking_not_supported, false,
> > + accumulation_not_supported },
> > + [R_RISCV_PLT32] = { apply_r_riscv_plt32_rela, false,
> > + accumulation_not_supported },
> > + [R_RISCV_SET_ULEB128] = { apply_r_riscv_set_uleb128, true,
> > + apply_uleb128_accumulation },
> > + [R_RISCV_SUB_ULEB128] = { apply_r_riscv_sub_uleb128, true,
> > + 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((unsigned long)location, hashtable_bits);
>
> uintptr_t
>
> > +
> > + 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)
> > @@ -349,11 +783,13 @@ 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;
> > @@ -371,8 +807,8 @@ 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;
> >
> > @@ -428,11 +864,16 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab,
> > }
> > }
> >
> > - res = handler(me, location, v);
> > + if (reloc_handlers[type].accumulate_relocations)
>
> As far as I can tell the table above has accumulate_relocations == false if and
> only if .accumulate_handler == accumulation_not_supported. Could we maybe drop
> the bool and just check for that?
>
> Are there situations where we might end up calling
> accumulation_not_supported()? If not we could just let .accumulate_handler be
> NULL where accumulation is not supported. Then the table could be initialised
> with
>
> { reloc_handler }, // when accumulation is not supported and
> { reloc_handler, accumulate_handler }, // when it is
>
> ..and the test above would just be
>
> if (reloc_handlers[type].accumulate_handler)
>
Yes it will always be the case that accumulate_relocations == false and
it uses accumulation_not_supported. This suggestion will make the code
much cleaner.
- Charlie
> > + 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
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > [email protected]
> > http://lists.infradead.org/mailman/listinfo/linux-riscv