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Message-ID: <CAJM55Z8Q7jG60TGakAhvg90zosdbNq8NeAuQeHVwHomvD+heAQ@mail.gmail.com>
Date: Wed, 1 Nov 2023 15:44:30 +0100
From: Emil Renner Berthing <emil.renner.berthing@...onical.com>
To: Charlie Jenkins <charlie@...osinc.com>,
linux-riscv@...ts.infradead.org, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Cc: Eric Biederman <ebiederm@...ssion.com>,
Kees Cook <keescook@...omium.org>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Andreas Schwab <schwab@...ux-m68k.org>,
Emil Renner Berthing <emil.renner.berthing@...onical.com>,
Samuel Holland <samuel.holland@...ive.com>,
Nelson Chu <nelson@...osinc.com>
Subject: Re: [PATCH v8 2/3] riscv: Add remaining module relocations
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 <charlie@...osinc.com>
> ---
> 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
>
>
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