* [PATCH mips-next 2/2] MIPS: relocatable: optimize the relocation process
2021-01-16 15:02 ` [PATCH mips-next 1/2] MIPS: module: optimize module " Alexander Lobakin
@ 2021-01-16 15:02 ` Alexander Lobakin
2021-01-18 1:49 ` [PATCH mips-next 1/2] MIPS: module: optimize module relocations processing Jiaxun Yang
1 sibling, 0 replies; 5+ messages in thread
From: Alexander Lobakin @ 2021-01-16 15:02 UTC (permalink / raw)
To: Thomas Bogendoerfer
Cc: Nathan Chancellor, Nick Desaulniers, Kees Cook, Andrew Morton,
Mike Rapoport, Alexander Lobakin, Jinyang He, linux-mips,
linux-kernel
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 <alobakin@pm.me>
---
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 47aeb3350a76..c643c816cbe0 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 @@ void *__init relocate_kernel(void)
/*
* Show relocation information on panic.
*/
-void show_kernel_relocation(const char *level)
+static void show_kernel_relocation(const char *level)
{
unsigned long offset;
--
2.30.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* Re: [PATCH mips-next 1/2] MIPS: module: optimize module relocations processing
2021-01-16 15:02 ` [PATCH mips-next 1/2] MIPS: module: optimize module " Alexander Lobakin
2021-01-16 15:02 ` [PATCH mips-next 2/2] MIPS: relocatable: optimize the relocation process Alexander Lobakin
@ 2021-01-18 1:49 ` Jiaxun Yang
1 sibling, 0 replies; 5+ messages in thread
From: Jiaxun Yang @ 2021-01-18 1:49 UTC (permalink / raw)
To: Alexander Lobakin, Thomas Bogendoerfer
Cc: Nathan Chancellor, Nick Desaulniers, Kees Cook, Andrew Morton,
Mike Rapoport, Jinyang He, linux-mips, linux-kernel
在 2021/1/16 下午11:02, Alexander Lobakin 写道:
> For now, module relocation functions are implemented as an array
> of handlers of type reloc_handler_t.
>
> 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].
>
> The result on MIPS32 R2 with GCC 10.2 -O2 is:
>
> scripts/bloat-o-meter -c arch/mips/kernel/__module.o arch/mips/kernel/module.o
> add/remove: 1/11 grow/shrink: 1/0 up/down: 876/-1436 (-560)
> Function old new delta
> apply_relocate 456 1148 +692
> apply_r_mips_pc - 184 +184
> apply_r_mips_none 8 - -8
> apply_r_mips_32 16 - -16
> apply_r_mips_64 76 - -76
> apply_r_mips_highest 88 - -88
> apply_r_mips_higher 108 - -108
> apply_r_mips_26 132 - -132
> apply_r_mips_pc26 160 - -160
> apply_r_mips_pc21 160 - -160
> apply_r_mips_pc16 160 - -160
> apply_r_mips_hi16 172 - -172
> apply_r_mips_lo16 356 - -356
> Total: Before=2608, After=2048, chg -21.47%
> add/remove: 0/0 grow/shrink: 0/0 up/down: 0/0 (0)
> Data old new delta
> Total: Before=12, After=12, chg +0.00%
> add/remove: 0/1 grow/shrink: 0/0 up/down: 0/-248 (-248)
> RO Data old new delta
> reloc_handlers 248 - -248
> Total: Before=248, After=0, chg -100.00%
>
> All functions were collapsed into a single one that is called
> directly by $(srctree)/kernel/module.c.
>
> Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> ---
> arch/mips/kernel/module.c | 109 ++++++++++++++++++--------------------
> 1 file changed, 52 insertions(+), 57 deletions(-)
>
> diff --git a/arch/mips/kernel/module.c b/arch/mips/kernel/module.c
> index 3c0c3d1260c1..14f46d17500a 100644
> --- a/arch/mips/kernel/module.c
> +++ b/arch/mips/kernel/module.c
> @@ -40,22 +40,13 @@ void *module_alloc(unsigned long size)
> }
> #endif
>
> -static int apply_r_mips_none(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela)
> -{
> - return 0;
> -}
> -
> -static int apply_r_mips_32(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela)
> +static void apply_r_mips_32(u32 *location, u32 base, Elf_Addr v)
> {
> *location = base + v;
> -
> - return 0;
> }
>
> -static int apply_r_mips_26(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela)
> +static int apply_r_mips_26(struct module *me, u32 *location, u32 base,
> + Elf_Addr v)
> {
> if (v % 4) {
> pr_err("module %s: dangerous R_MIPS_26 relocation\n",
> @@ -75,8 +66,8 @@ static int apply_r_mips_26(struct module *me, u32 *location,
> return 0;
> }
>
> -static int apply_r_mips_hi16(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela)
> +static int apply_r_mips_hi16(struct module *me, u32 *location, Elf_Addr v,
> + bool rela)
> {
> struct mips_hi16 *n;
>
> @@ -217,26 +208,25 @@ static int apply_r_mips_pc(struct module *me, u32 *location, u32 base,
> return 0;
> }
>
> -static int apply_r_mips_pc16(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela)
> +static int apply_r_mips_pc16(struct module *me, u32 *location, u32 base,
> + Elf_Addr v)
> {
> return apply_r_mips_pc(me, location, base, v, 16);
> }
>
> -static int apply_r_mips_pc21(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela)
> +static int apply_r_mips_pc21(struct module *me, u32 *location, u32 base,
> + Elf_Addr v)
> {
> return apply_r_mips_pc(me, location, base, v, 21);
> }
>
> -static int apply_r_mips_pc26(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela)
> +static int apply_r_mips_pc26(struct module *me, u32 *location, u32 base,
> + Elf_Addr v)
> {
> return apply_r_mips_pc(me, location, base, v, 26);
> }
>
> -static int apply_r_mips_64(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela)
> +static int apply_r_mips_64(u32 *location, Elf_Addr v, bool rela)
> {
> if (WARN_ON(!rela))
> return -EINVAL;
> @@ -246,8 +236,7 @@ static int apply_r_mips_64(struct module *me, u32 *location,
> return 0;
> }
>
> -static int apply_r_mips_higher(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela)
> +static int apply_r_mips_higher(u32 *location, Elf_Addr v, bool rela)
> {
> if (WARN_ON(!rela))
> return -EINVAL;
> @@ -258,8 +247,7 @@ static int apply_r_mips_higher(struct module *me, u32 *location,
> return 0;
> }
>
> -static int apply_r_mips_highest(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela)
> +static int apply_r_mips_highest(u32 *location, Elf_Addr v, bool rela)
> {
> if (WARN_ON(!rela))
> return -EINVAL;
> @@ -272,12 +260,14 @@ static int apply_r_mips_highest(struct module *me, u32 *location,
>
> /**
> * reloc_handler() - Apply a particular relocation to a module
> + * @type: type of the relocation to apply
> * @me: the module to apply the reloc to
> * @location: the address at which the reloc is to be applied
> * @base: the existing value at location for REL-style; 0 for RELA-style
> * @v: the value of the reloc, with addend for RELA-style
> + * @rela: indication of is this a RELA (true) or REL (false) relocation
> *
> - * Each implemented reloc_handler function applies a particular type of
> + * Each implemented relocation function applies a particular type of
> * relocation to the module @me. Relocs that may be found in either REL or RELA
> * variants can be handled by making use of the @base & @v parameters which are
> * set to values which abstract the difference away from the particular reloc
> @@ -285,23 +275,40 @@ static int apply_r_mips_highest(struct module *me, u32 *location,
> *
> * Return: 0 upon success, else -ERRNO
> */
> -typedef int (*reloc_handler)(struct module *me, u32 *location,
> - u32 base, Elf_Addr v, bool rela);
> -
> -/* The handlers for known reloc types */
> -static reloc_handler reloc_handlers[] = {
> - [R_MIPS_NONE] = apply_r_mips_none,
> - [R_MIPS_32] = apply_r_mips_32,
> - [R_MIPS_26] = apply_r_mips_26,
> - [R_MIPS_HI16] = apply_r_mips_hi16,
> - [R_MIPS_LO16] = apply_r_mips_lo16,
> - [R_MIPS_PC16] = apply_r_mips_pc16,
> - [R_MIPS_64] = apply_r_mips_64,
> - [R_MIPS_HIGHER] = apply_r_mips_higher,
> - [R_MIPS_HIGHEST] = apply_r_mips_highest,
> - [R_MIPS_PC21_S2] = apply_r_mips_pc21,
> - [R_MIPS_PC26_S2] = apply_r_mips_pc26,
> -};
> +static int reloc_handler(u32 type, struct module *me, u32 *location, u32 base,
> + Elf_Addr v, bool rela)
> +{
> + switch (type) {
> + case R_MIPS_NONE:
> + break;
> + case R_MIPS_32:
> + apply_r_mips_32(location, base, v);
> + break;
> + case R_MIPS_26:
> + return apply_r_mips_26(me, location, base, v);
> + case R_MIPS_HI16:
> + return apply_r_mips_hi16(me, location, v, rela);
> + case R_MIPS_LO16:
> + return apply_r_mips_lo16(me, location, base, v, rela);
> + case R_MIPS_PC16:
> + return apply_r_mips_pc16(me, location, base, v);
> + case R_MIPS_PC21_S2:
> + return apply_r_mips_pc21(me, location, base, v);
> + case R_MIPS_PC26_S2:
> + return apply_r_mips_pc26(me, location, base, v);
> + case R_MIPS_64:
> + return apply_r_mips_64(location, v, rela);
> + case R_MIPS_HIGHER:
> + return apply_r_mips_higher(location, v, rela);
> + case R_MIPS_HIGHEST:
> + return apply_r_mips_highest(location, v, rela);
> + default:
> + pr_err("%s: Unknown relocation type %u\n", me->name, type);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
>
> static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
> unsigned int symindex, unsigned int relsec,
> @@ -311,7 +318,6 @@ static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
> Elf_Mips_Rel *rel;
> Elf_Mips_Rela *rela;
> } r;
> - reloc_handler handler;
> Elf_Sym *sym;
> u32 *location, base;
> unsigned int i, type;
> @@ -343,17 +349,6 @@ static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
> }
>
> type = ELF_MIPS_R_TYPE(*r.rel);
> - if (type < ARRAY_SIZE(reloc_handlers))
> - handler = reloc_handlers[type];
> - else
> - handler = NULL;
> -
> - if (!handler) {
> - pr_err("%s: Unknown relocation type %u\n",
> - me->name, type);
> - err = -EINVAL;
> - goto out;
> - }
>
> if (rela) {
> v = sym->st_value + r.rela->r_addend;
> @@ -365,7 +360,7 @@ static int __apply_relocate(Elf_Shdr *sechdrs, const char *strtab,
> r.rel = &r.rel[1];
> }
>
> - err = handler(me, location, base, v, rela);
> + err = reloc_handler(type, me, location, base, v, rela);
> if (err)
> goto out;
> }
^ permalink raw reply [flat|nested] 5+ messages in thread