From 080c4324fa5e81ff3780206a138223abfb57a68e Mon Sep 17 00:00:00 2001 From: Maxim Kochetkov Date: Thu, 14 Dec 2023 09:39:06 +0300 Subject: [PATCH] riscv: optimize ELF relocation function in riscv The patch can optimize the running times of insmod command by modify ELF relocation function. In the 5.10 and latest kernel, when install the riscv ELF drivers which contains multiple symbol table items to be relocated, kernel takes a lot of time to execute the relocation. For example, we install a 3+MB driver need 180+s. We focus on the riscv architecture handle R_RISCV_HI20 and R_RISCV_LO20 type items relocation function in the arch\riscv\kernel\module.c and find that there are two-loops in the function. If we modify the begin number in the second for-loops iteration, we could save significant time for installation. We install the same 3+MB driver could just need 2s. Signed-off-by: Amma Lee Signed-off-by: Maxim Kochetkov Reviewed-by: Charlie Jenkins Link: https://lore.kernel.org/r/20231214063906.13612-1-fido_max@inbox.ru Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/module.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/arch/riscv/kernel/module.c b/arch/riscv/kernel/module.c index c9d59a5448b6c..5e5a82644451e 100644 --- a/arch/riscv/kernel/module.c +++ b/arch/riscv/kernel/module.c @@ -783,6 +783,7 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, Elf_Sym *sym; void *location; unsigned int i, type; + unsigned int j_idx = 0; Elf_Addr v; int res; unsigned int num_relocations = sechdrs[relsec].sh_size / sizeof(*rel); @@ -833,9 +834,10 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, v = sym->st_value + rel[i].r_addend; if (type == R_RISCV_PCREL_LO12_I || type == R_RISCV_PCREL_LO12_S) { - unsigned int j; + unsigned int j = j_idx; + bool found = false; - for (j = 0; j < sechdrs[relsec].sh_size / sizeof(*rel); j++) { + do { unsigned long hi20_loc = sechdrs[sechdrs[relsec].sh_info].sh_addr + rel[j].r_offset; @@ -864,16 +866,26 @@ int apply_relocate_add(Elf_Shdr *sechdrs, const char *strtab, hi20 = (offset + 0x800) & 0xfffff000; lo12 = offset - hi20; v = lo12; + found = true; break; } - } - if (j == sechdrs[relsec].sh_size / sizeof(*rel)) { + + j++; + if (j > sechdrs[relsec].sh_size / sizeof(*rel)) + j = 0; + + } while (j_idx != j); + + if (!found) { pr_err( "%s: Can not find HI20 relocation information\n", me->name); return -EINVAL; } + + /* Record the previous j-loop end index */ + j_idx = j; } if (reloc_handlers[type].accumulate_handler) -- 2.30.2