From d9e84fb1a34efd0ca3f68f481a051f26a952e383 Mon Sep 17 00:00:00 2001 From: Alexander Lobakin Date: Sat, 16 Jan 2021 15:02:53 +0000 Subject: [PATCH] MIPS: relocatable: optimize the relocation process For now, vmlinux relocation functions for relocatable kernel are implemented as an array of handlers of a particular type. Convert that array into a single switch-case function to: - remove unused arguments; - change the return type of simple handlers to void; - remove the array and don't use any data at all; - avoid using indirect calls; - allow the compiler to inline and greatly optimize the relocation function[s]; and also mark do_relocations() and show_kernel_relocation() static as they aren't used anywhere else. The result on MIPS32 R2 with GCC 10.2 -O2 is: scripts/bloat-o-meter -c arch/mips/kernel/__relocate.o arch/mips/kernel/relocate.o add/remove: 0/6 grow/shrink: 1/0 up/down: 356/-640 (-284) Function old new delta relocate_kernel 852 1208 +356 apply_r_mips_32_rel 20 - -20 apply_r_mips_hi16_rel 40 - -40 apply_r_mips_64_rel 44 - -44 apply_r_mips_26_rel 144 - -144 show_kernel_relocation 164 - -164 do_relocations 228 - -228 Total: Before=1780, After=1496, chg -15.96% add/remove: 0/1 grow/shrink: 0/0 up/down: 0/-76 (-76) Data old new delta reloc_handlers_rel 76 - -76 Total: Before=92, After=16, chg -82.61% add/remove: 0/0 grow/shrink: 0/0 up/down: 0/0 (0) RO Data old new delta Total: Before=0, After=0, chg +0.00% All functions were collapsed into the main one, relocate_kernel(). Signed-off-by: Alexander Lobakin Signed-off-by: Thomas Bogendoerfer --- arch/mips/kernel/relocate.c | 54 +++++++++++++++++++++++++-------------------- 1 file changed, 30 insertions(+), 24 deletions(-) diff --git a/arch/mips/kernel/relocate.c b/arch/mips/kernel/relocate.c index 47aeb33..c643c81 100644 --- a/arch/mips/kernel/relocate.c +++ b/arch/mips/kernel/relocate.c @@ -70,18 +70,14 @@ static void __init sync_icache(void *kbase, unsigned long kernel_length) __sync(); } -static int __init apply_r_mips_64_rel(u32 *loc_orig, u32 *loc_new, long offset) +static void __init apply_r_mips_64_rel(u32 *loc_new, long offset) { *(u64 *)loc_new += offset; - - return 0; } -static int __init apply_r_mips_32_rel(u32 *loc_orig, u32 *loc_new, long offset) +static void __init apply_r_mips_32_rel(u32 *loc_new, long offset) { *loc_new += offset; - - return 0; } static int __init apply_r_mips_26_rel(u32 *loc_orig, u32 *loc_new, long offset) @@ -114,7 +110,8 @@ static int __init apply_r_mips_26_rel(u32 *loc_orig, u32 *loc_new, long offset) } -static int __init apply_r_mips_hi16_rel(u32 *loc_orig, u32 *loc_new, long offset) +static void __init apply_r_mips_hi16_rel(u32 *loc_orig, u32 *loc_new, + long offset) { unsigned long insn = *loc_orig; unsigned long target = (insn & 0xffff) << 16; /* high 16bits of target */ @@ -122,17 +119,33 @@ static int __init apply_r_mips_hi16_rel(u32 *loc_orig, u32 *loc_new, long offset target += offset; *loc_new = (insn & ~0xffff) | ((target >> 16) & 0xffff); - return 0; } -static int (*reloc_handlers_rel[]) (u32 *, u32 *, long) __initdata = { - [R_MIPS_64] = apply_r_mips_64_rel, - [R_MIPS_32] = apply_r_mips_32_rel, - [R_MIPS_26] = apply_r_mips_26_rel, - [R_MIPS_HI16] = apply_r_mips_hi16_rel, -}; +static int __init reloc_handler(u32 type, u32 *loc_orig, u32 *loc_new, + long offset) +{ + switch (type) { + case R_MIPS_64: + apply_r_mips_64_rel(loc_new, offset); + break; + case R_MIPS_32: + apply_r_mips_32_rel(loc_new, offset); + break; + case R_MIPS_26: + return apply_r_mips_26_rel(loc_orig, loc_new, offset); + case R_MIPS_HI16: + apply_r_mips_hi16_rel(loc_orig, loc_new, offset); + break; + default: + pr_err("Unhandled relocation type %d at 0x%pK\n", type, + loc_orig); + return -ENOEXEC; + } -int __init do_relocations(void *kbase_old, void *kbase_new, long offset) + return 0; +} + +static int __init do_relocations(void *kbase_old, void *kbase_new, long offset) { u32 *r; u32 *loc_orig; @@ -149,14 +162,7 @@ int __init do_relocations(void *kbase_old, void *kbase_new, long offset) loc_orig = kbase_old + ((*r & 0x00ffffff) << 2); loc_new = RELOCATED(loc_orig); - if (reloc_handlers_rel[type] == NULL) { - /* Unsupported relocation */ - pr_err("Unhandled relocation type %d at 0x%pK\n", - type, loc_orig); - return -ENOEXEC; - } - - res = reloc_handlers_rel[type](loc_orig, loc_new, offset); + res = reloc_handler(type, loc_orig, loc_new, offset); if (res) return res; } @@ -412,7 +418,7 @@ out: /* * Show relocation information on panic. */ -void show_kernel_relocation(const char *level) +static void show_kernel_relocation(const char *level) { unsigned long offset; -- 2.7.4