[RFC/PATCH 3/3] ARM: Replace calls to __aeabi_{u}idiv with udiv/sdiv instructions

Måns Rullgård
2015-11-23T20:54:48Z

Stephen Boyd <sboyd@codeaurora.org> writes:

> On 11/21, M?ns Rullg?rd wrote:
>> Stephen Boyd <sboyd@codeaurora.org> writes:
>>
>> > +static int module_patch_aeabi_uidiv(unsigned long loc, const Elf32_Sym *sym)
>> > +{
>> > + extern char __aeabi_uidiv[], __aeabi_idiv[];
>> > + unsigned long udiv_addr = (unsigned long)__aeabi_uidiv;
>> > + unsigned long sdiv_addr = (unsigned long)__aeabi_idiv;
>> > + unsigned int udiv_insn, sdiv_insn, mask;
>> > +
>> > + if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
>> > + mask = HWCAP_IDIVT;
>> > + udiv_insn = __opcode_to_mem_thumb32(0xfbb0f0f1);
>> > + sdiv_insn = __opcode_to_mem_thumb32(0xfb90f0f1);
>> > + } else {
>> > + mask = HWCAP_IDIVA;
>> > + udiv_insn = __opcode_to_mem_arm(0xe730f110);
>> > + sdiv_insn = __opcode_to_mem_arm(0xe710f110);
>> > + }
>> > +
>> > + if (elf_hwcap & mask) {
>> > + if (sym->st_value == udiv_addr) {
>> > + *(u32 *)loc = udiv_insn;
>> > + return 1;
>> > + } else if (sym->st_value == sdiv_addr) {
>> > + *(u32 *)loc = sdiv_insn;
>> > + return 1;
>> > + }
>> > + }
>> > +
>> > + return 0;
>> > +}
>>
>> [...]
>>
>> > +static void __init patch_aeabi_uidiv(void)
>> > +{
>> > + extern unsigned long *__start_udiv_loc[], *__stop_udiv_loc[];
>> > + extern unsigned long *__start_idiv_loc[], *__stop_idiv_loc[];
>> > + unsigned long **p;
>> > + unsigned int udiv_insn, sdiv_insn, mask;
>> > +
>> > + if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
>> > + mask = HWCAP_IDIVT;
>> > + udiv_insn = __opcode_to_mem_thumb32(0xfbb0f0f1);
>> > + sdiv_insn = __opcode_to_mem_thumb32(0xfb90f0f1);
>> > + } else {
>> > + mask = HWCAP_IDIVA;
>> > + udiv_insn = __opcode_to_mem_arm(0xe730f110);
>> > + sdiv_insn = __opcode_to_mem_arm(0xe710f110);
>> > + }
>> > +
>> > + if (elf_hwcap & mask) {
>> > + for (p = __start_udiv_loc; p < __stop_udiv_loc; p++) {
>> > + unsigned long *inst = *p;
>> > + *inst = udiv_insn;
>> > + }
>> > + for (p = __start_idiv_loc; p < __stop_idiv_loc; p++) {
>> > + unsigned long *inst = *p;
>> > + *inst = sdiv_insn;
>> > + }
>> > + }
>> > +}
>>
>> These functions are rather similar. Perhaps they could be combined
>> somehow.
>>
>
> Yes. I have this patch on top, just haven't folded it in because
> it doesn't reduce the lines of code.

I don't see any reason to split it anyhow. The end result isn't any
harder to understand than the intermediate.

> ----8<----
> From: Stephen Boyd <sboyd@codeaurora.org>
> Subject: [PATCH] consolidate with module code
>
> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> ---
> arch/arm/include/asm/setup.h | 3 +++
> arch/arm/kernel/module.c | 16 +++++--------
> arch/arm/kernel/setup.c | 54 +++++++++++++++++++++++++++-----------------
> 3 files changed, 42 insertions(+), 31 deletions(-)
>
> diff --git a/arch/arm/include/asm/setup.h b/arch/arm/include/asm/setup.h
> index e0adb9f1bf94..3f251cdb94ef 100644
> --- a/arch/arm/include/asm/setup.h
> +++ b/arch/arm/include/asm/setup.h
> @@ -25,4 +25,7 @@ extern int arm_add_memory(u64 start, u64 size);
> extern void early_print(const char *str, ...);
> extern void dump_machine_table(void);
>
> +extern void patch_uidiv(void *addr, size_t size);
> +extern void patch_idiv(void *addr, size_t size);

Why not call things sdiv and udiv like the actual instructions?

> #endif
> diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c
> index 064e6ae60e08..684a68f1085b 100644
> --- a/arch/arm/kernel/module.c
> +++ b/arch/arm/kernel/module.c
> @@ -22,6 +22,7 @@
>
> #include <asm/hwcap.h>
> #include <asm/pgtable.h>
> +#include <asm/setup.h>
> #include <asm/sections.h>
> #include <asm/smp_plat.h>
> #include <asm/unwind.h>
> @@ -58,24 +59,19 @@ static int module_patch_aeabi_uidiv(unsigned long loc, const Elf32_Sym *sym)
> extern char __aeabi_uidiv[], __aeabi_idiv[];
> unsigned long udiv_addr = (unsigned long)__aeabi_uidiv;
> unsigned long sdiv_addr = (unsigned long)__aeabi_idiv;
> - unsigned int udiv_insn, sdiv_insn, mask;
> + unsigned int mask;
>
> - if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
> + if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
> mask = HWCAP_IDIVT;
> - udiv_insn = __opcode_to_mem_thumb32(0xfbb0f0f1);
> - sdiv_insn = __opcode_to_mem_thumb32(0xfb90f0f1);
> - } else {
> + else
> mask = HWCAP_IDIVA;
> - udiv_insn = __opcode_to_mem_arm(0xe730f110);
> - sdiv_insn = __opcode_to_mem_arm(0xe710f110);
> - }
>
> if (elf_hwcap & mask) {
> if (sym->st_value == udiv_addr) {
> - *(u32 *)loc = udiv_insn;
> + patch_uidiv(&loc, sizeof(loc));
> return 1;
> } else if (sym->st_value == sdiv_addr) {
> - *(u32 *)loc = sdiv_insn;
> + patch_idiv(&loc, sizeof(loc));
> return 1;
> }
> }
> diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
> index d2a3d165dcae..cb86012c47d1 100644
> --- a/arch/arm/kernel/setup.c
> +++ b/arch/arm/kernel/setup.c
> @@ -376,33 +376,45 @@ void __init early_print(const char *str, ...)
> }
>
> #ifdef CONFIG_ARM_PATCH_UIDIV
> +static void __init_or_module patch(u32 **addr, size_t count, u32 insn)
> +{
> + for (; count != 0; count -= 4)
> + **addr++ = insn;
> +}
> +
> +void __init_or_module patch_uidiv(void *addr, size_t size)
> +{
> + if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
> + patch(addr, size, __opcode_to_mem_thumb32(0xfbb0f0f1));
> + else
> + patch(addr, size, __opcode_to_mem_arm(0xe730f110));
> +
> +}
> +
> +void __init_or_module patch_idiv(void *addr, size_t size)
> +{
> + if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
> + patch(addr, size, __opcode_to_mem_thumb32(0xfb90f0f1));
> + else
> + patch(addr, size, __opcode_to_mem_arm(0xe710f110));
> +}
> +
> static void __init patch_aeabi_uidiv(void)
> {
> - extern unsigned long *__start_udiv_loc[], *__stop_udiv_loc[];
> - extern unsigned long *__start_idiv_loc[], *__stop_idiv_loc[];
> - unsigned long **p;
> - unsigned int udiv_insn, sdiv_insn, mask;
> + extern char __start_udiv_loc[], __stop_udiv_loc[];
> + extern char __start_idiv_loc[], __stop_idiv_loc[];
> + unsigned int mask;
>
> - if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) {
> + if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
> mask = HWCAP_IDIVT;
> - udiv_insn = __opcode_to_mem_thumb32(0xfbb0f0f1);
> - sdiv_insn = __opcode_to_mem_thumb32(0xfb90f0f1);
> - } else {
> + else
> mask = HWCAP_IDIVA;
> - udiv_insn = __opcode_to_mem_arm(0xe730f110);
> - sdiv_insn = __opcode_to_mem_arm(0xe710f110);
> - }
>
> - if (elf_hwcap & mask) {
> - for (p = __start_udiv_loc; p < __stop_udiv_loc; p++) {
> - unsigned long *inst = *p;
> - *inst = udiv_insn;
> - }
> - for (p = __start_idiv_loc; p < __stop_idiv_loc; p++) {
> - unsigned long *inst = *p;
> - *inst = sdiv_insn;
> - }
> - }
> + if (!(elf_hwcap & mask))
> + return;
> +
> + patch_uidiv(__start_udiv_loc, __stop_udiv_loc - __start_udiv_loc);
> + patch_idiv(__start_idiv_loc, __stop_idiv_loc - __start_idiv_loc);
> }
> #else
> static void __init patch_aeabi_uidiv(void) { }
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project

--
M?ns Rullg?rd
mans at mansr.com