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Date: Wed, 20 May 2015 11:56:41 -0700
From: Brian Norris <computersforpeace@...il.com>
To: Denys Vlasenko <dvlasenk@...hat.com>
Cc: David Woodhouse <David.Woodhouse@...el.com>,
Dan Carpenter <dan.carpenter@...cle.com>,
Jingoo Han <jg1.han@...sung.com>,
Aaron Sierra <asierra@...-inc.com>,
Artem Bityutskiy <Artem.Bityutskiy@...ux.intel.com>,
linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mtd: cfi: Deiline large functions
On Mon, May 18, 2015 at 12:58:40PM +0200, Denys Vlasenko wrote:
> With this .config: http://busybox.net/~vda/kernel_config,
> after uninlining these functions have sizes and callsite counts
> as follows:
Most of this is probably good, thanks. But I'm curious about one:
> cfi_udelay(): 74 bytes, 26 callsites
^^ This is pretty dead-simple. If it's generating bad code, we might
look at fixing it up instead. Almost all of its call sites are with
constant input, so it *should* just become:
udelay(1);
cond_resched();
in most cases. For the non-constant cases, we might still do an
out-of-line implementation. Or maybe we just say it's all not worth it,
and we just stick with what you have. But I'd like to consider
alternatives to out-lining this one.
Thanks,
Brian
> cfi_send_gen_cmd(): 153 bytes, 95 callsites
> cfi_build_cmd(): 274 bytes, 123 callsites
> cfi_build_cmd_addr(): 49 bytes, 15 callsites
> cfi_merge_status(): 230 bytes, 3 callsites
>
> Reduction in code size is about 50,000:
>
> text data bss dec hex filename
> 85842882 22294584 20627456 128764922 7accbfa vmlinux.before
> 85789648 22294616 20627456 128711720 7abfc28 vmlinux
>
> Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
> CC: Dan Carpenter <dan.carpenter@...cle.com>
> CC: Jingoo Han <jg1.han@...sung.com>
> CC: Brian Norris <computersforpeace@...il.com>
> CC: Aaron Sierra <asierra@...-inc.com>
> CC: Artem Bityutskiy <Artem.Bityutskiy@...ux.intel.com>
> CC: David Woodhouse <David.Woodhouse@...el.com>
> CC: linux-mtd@...ts.infradead.org
> CC: linux-kernel@...r.kernel.org
> ---
> drivers/mtd/chips/cfi_util.c | 188 +++++++++++++++++++++++++++++++++++++++++++
> include/linux/mtd/cfi.h | 188 ++-----------------------------------------
> 2 files changed, 196 insertions(+), 180 deletions(-)
>
> diff --git a/drivers/mtd/chips/cfi_util.c b/drivers/mtd/chips/cfi_util.c
> index 09c79bd..6f16552 100644
> --- a/drivers/mtd/chips/cfi_util.c
> +++ b/drivers/mtd/chips/cfi_util.c
> @@ -23,6 +23,194 @@
> #include <linux/mtd/map.h>
> #include <linux/mtd/cfi.h>
>
> +void cfi_udelay(int us)
> +{
> + if (us >= 1000) {
> + msleep((us+999)/1000);
> + } else {
> + udelay(us);
> + cond_resched();
> + }
> +}
> +EXPORT_SYMBOL(cfi_udelay);
> +
> +/*
> + * Returns the command address according to the given geometry.
> + */
> +uint32_t cfi_build_cmd_addr(uint32_t cmd_ofs,
> + struct map_info *map, struct cfi_private *cfi)
> +{
> + unsigned bankwidth = map_bankwidth(map);
> + unsigned interleave = cfi_interleave(cfi);
> + unsigned type = cfi->device_type;
> + uint32_t addr;
> +
> + addr = (cmd_ofs * type) * interleave;
> +
> + /* Modify the unlock address if we are in compatibility mode.
> + * For 16bit devices on 8 bit busses
> + * and 32bit devices on 16 bit busses
> + * set the low bit of the alternating bit sequence of the address.
> + */
> + if (((type * interleave) > bankwidth) && ((cmd_ofs & 0xff) == 0xaa))
> + addr |= (type >> 1)*interleave;
> +
> + return addr;
> +}
> +EXPORT_SYMBOL(cfi_build_cmd_addr);
> +
> +/*
> + * Transforms the CFI command for the given geometry (bus width & interleave).
> + * It looks too long to be inline, but in the common case it should almost all
> + * get optimised away.
> + */
> +map_word cfi_build_cmd(u_long cmd, struct map_info *map, struct cfi_private *cfi)
> +{
> + map_word val = { {0} };
> + int wordwidth, words_per_bus, chip_mode, chips_per_word;
> + unsigned long onecmd;
> + int i;
> +
> + /* We do it this way to give the compiler a fighting chance
> + of optimising away all the crap for 'bankwidth' larger than
> + an unsigned long, in the common case where that support is
> + disabled */
> + if (map_bankwidth_is_large(map)) {
> + wordwidth = sizeof(unsigned long);
> + words_per_bus = (map_bankwidth(map)) / wordwidth; // i.e. normally 1
> + } else {
> + wordwidth = map_bankwidth(map);
> + words_per_bus = 1;
> + }
> +
> + chip_mode = map_bankwidth(map) / cfi_interleave(cfi);
> + chips_per_word = wordwidth * cfi_interleave(cfi) / map_bankwidth(map);
> +
> + /* First, determine what the bit-pattern should be for a single
> + device, according to chip mode and endianness... */
> + switch (chip_mode) {
> + default: BUG();
> + case 1:
> + onecmd = cmd;
> + break;
> + case 2:
> + onecmd = cpu_to_cfi16(map, cmd);
> + break;
> + case 4:
> + onecmd = cpu_to_cfi32(map, cmd);
> + break;
> + }
> +
> + /* Now replicate it across the size of an unsigned long, or
> + just to the bus width as appropriate */
> + switch (chips_per_word) {
> + default: BUG();
> +#if BITS_PER_LONG >= 64
> + case 8:
> + onecmd |= (onecmd << (chip_mode * 32));
> +#endif
> + case 4:
> + onecmd |= (onecmd << (chip_mode * 16));
> + case 2:
> + onecmd |= (onecmd << (chip_mode * 8));
> + case 1:
> + ;
> + }
> +
> + /* And finally, for the multi-word case, replicate it
> + in all words in the structure */
> + for (i=0; i < words_per_bus; i++) {
> + val.x[i] = onecmd;
> + }
> +
> + return val;
> +}
> +EXPORT_SYMBOL(cfi_build_cmd);
> +
> +unsigned long cfi_merge_status(map_word val, struct map_info *map,
> + struct cfi_private *cfi)
> +{
> + int wordwidth, words_per_bus, chip_mode, chips_per_word;
> + unsigned long onestat, res = 0;
> + int i;
> +
> + /* We do it this way to give the compiler a fighting chance
> + of optimising away all the crap for 'bankwidth' larger than
> + an unsigned long, in the common case where that support is
> + disabled */
> + if (map_bankwidth_is_large(map)) {
> + wordwidth = sizeof(unsigned long);
> + words_per_bus = (map_bankwidth(map)) / wordwidth; // i.e. normally 1
> + } else {
> + wordwidth = map_bankwidth(map);
> + words_per_bus = 1;
> + }
> +
> + chip_mode = map_bankwidth(map) / cfi_interleave(cfi);
> + chips_per_word = wordwidth * cfi_interleave(cfi) / map_bankwidth(map);
> +
> + onestat = val.x[0];
> + /* Or all status words together */
> + for (i=1; i < words_per_bus; i++) {
> + onestat |= val.x[i];
> + }
> +
> + res = onestat;
> + switch(chips_per_word) {
> + default: BUG();
> +#if BITS_PER_LONG >= 64
> + case 8:
> + res |= (onestat >> (chip_mode * 32));
> +#endif
> + case 4:
> + res |= (onestat >> (chip_mode * 16));
> + case 2:
> + res |= (onestat >> (chip_mode * 8));
> + case 1:
> + ;
> + }
> +
> + /* Last, determine what the bit-pattern should be for a single
> + device, according to chip mode and endianness... */
> + switch (chip_mode) {
> + case 1:
> + break;
> + case 2:
> + res = cfi16_to_cpu(map, res);
> + break;
> + case 4:
> + res = cfi32_to_cpu(map, res);
> + break;
> + default: BUG();
> + }
> + return res;
> +}
> +EXPORT_SYMBOL(cfi_merge_status);
> +
> +/*
> + * Sends a CFI command to a bank of flash for the given geometry.
> + *
> + * Returns the offset in flash where the command was written.
> + * If prev_val is non-null, it will be set to the value at the command address,
> + * before the command was written.
> + */
> +uint32_t cfi_send_gen_cmd(u_char cmd, uint32_t cmd_addr, uint32_t base,
> + struct map_info *map, struct cfi_private *cfi,
> + int type, map_word *prev_val)
> +{
> + map_word val;
> + uint32_t addr = base + cfi_build_cmd_addr(cmd_addr, map, cfi);
> + val = cfi_build_cmd(cmd, map, cfi);
> +
> + if (prev_val)
> + *prev_val = map_read(map, addr);
> +
> + map_write(map, val, addr);
> +
> + return addr - base;
> +}
> +EXPORT_SYMBOL(cfi_send_gen_cmd);
> +
> int __xipram cfi_qry_present(struct map_info *map, __u32 base,
> struct cfi_private *cfi)
> {
> diff --git a/include/linux/mtd/cfi.h b/include/linux/mtd/cfi.h
> index 299d7d3..9b57a9b 100644
> --- a/include/linux/mtd/cfi.h
> +++ b/include/linux/mtd/cfi.h
> @@ -296,183 +296,19 @@ struct cfi_private {
> struct flchip chips[0]; /* per-chip data structure for each chip */
> };
>
> -/*
> - * Returns the command address according to the given geometry.
> - */
> -static inline uint32_t cfi_build_cmd_addr(uint32_t cmd_ofs,
> - struct map_info *map, struct cfi_private *cfi)
> -{
> - unsigned bankwidth = map_bankwidth(map);
> - unsigned interleave = cfi_interleave(cfi);
> - unsigned type = cfi->device_type;
> - uint32_t addr;
> -
> - addr = (cmd_ofs * type) * interleave;
> -
> - /* Modify the unlock address if we are in compatibility mode.
> - * For 16bit devices on 8 bit busses
> - * and 32bit devices on 16 bit busses
> - * set the low bit of the alternating bit sequence of the address.
> - */
> - if (((type * interleave) > bankwidth) && ((cmd_ofs & 0xff) == 0xaa))
> - addr |= (type >> 1)*interleave;
> -
> - return addr;
> -}
> -
> -/*
> - * Transforms the CFI command for the given geometry (bus width & interleave).
> - * It looks too long to be inline, but in the common case it should almost all
> - * get optimised away.
> - */
> -static inline map_word cfi_build_cmd(u_long cmd, struct map_info *map, struct cfi_private *cfi)
> -{
> - map_word val = { {0} };
> - int wordwidth, words_per_bus, chip_mode, chips_per_word;
> - unsigned long onecmd;
> - int i;
> -
> - /* We do it this way to give the compiler a fighting chance
> - of optimising away all the crap for 'bankwidth' larger than
> - an unsigned long, in the common case where that support is
> - disabled */
> - if (map_bankwidth_is_large(map)) {
> - wordwidth = sizeof(unsigned long);
> - words_per_bus = (map_bankwidth(map)) / wordwidth; // i.e. normally 1
> - } else {
> - wordwidth = map_bankwidth(map);
> - words_per_bus = 1;
> - }
> -
> - chip_mode = map_bankwidth(map) / cfi_interleave(cfi);
> - chips_per_word = wordwidth * cfi_interleave(cfi) / map_bankwidth(map);
> -
> - /* First, determine what the bit-pattern should be for a single
> - device, according to chip mode and endianness... */
> - switch (chip_mode) {
> - default: BUG();
> - case 1:
> - onecmd = cmd;
> - break;
> - case 2:
> - onecmd = cpu_to_cfi16(map, cmd);
> - break;
> - case 4:
> - onecmd = cpu_to_cfi32(map, cmd);
> - break;
> - }
> -
> - /* Now replicate it across the size of an unsigned long, or
> - just to the bus width as appropriate */
> - switch (chips_per_word) {
> - default: BUG();
> -#if BITS_PER_LONG >= 64
> - case 8:
> - onecmd |= (onecmd << (chip_mode * 32));
> -#endif
> - case 4:
> - onecmd |= (onecmd << (chip_mode * 16));
> - case 2:
> - onecmd |= (onecmd << (chip_mode * 8));
> - case 1:
> - ;
> - }
> +uint32_t cfi_build_cmd_addr(uint32_t cmd_ofs,
> + struct map_info *map, struct cfi_private *cfi);
>
> - /* And finally, for the multi-word case, replicate it
> - in all words in the structure */
> - for (i=0; i < words_per_bus; i++) {
> - val.x[i] = onecmd;
> - }
> -
> - return val;
> -}
> +map_word cfi_build_cmd(u_long cmd, struct map_info *map, struct cfi_private *cfi);
> #define CMD(x) cfi_build_cmd((x), map, cfi)
>
> -
> -static inline unsigned long cfi_merge_status(map_word val, struct map_info *map,
> - struct cfi_private *cfi)
> -{
> - int wordwidth, words_per_bus, chip_mode, chips_per_word;
> - unsigned long onestat, res = 0;
> - int i;
> -
> - /* We do it this way to give the compiler a fighting chance
> - of optimising away all the crap for 'bankwidth' larger than
> - an unsigned long, in the common case where that support is
> - disabled */
> - if (map_bankwidth_is_large(map)) {
> - wordwidth = sizeof(unsigned long);
> - words_per_bus = (map_bankwidth(map)) / wordwidth; // i.e. normally 1
> - } else {
> - wordwidth = map_bankwidth(map);
> - words_per_bus = 1;
> - }
> -
> - chip_mode = map_bankwidth(map) / cfi_interleave(cfi);
> - chips_per_word = wordwidth * cfi_interleave(cfi) / map_bankwidth(map);
> -
> - onestat = val.x[0];
> - /* Or all status words together */
> - for (i=1; i < words_per_bus; i++) {
> - onestat |= val.x[i];
> - }
> -
> - res = onestat;
> - switch(chips_per_word) {
> - default: BUG();
> -#if BITS_PER_LONG >= 64
> - case 8:
> - res |= (onestat >> (chip_mode * 32));
> -#endif
> - case 4:
> - res |= (onestat >> (chip_mode * 16));
> - case 2:
> - res |= (onestat >> (chip_mode * 8));
> - case 1:
> - ;
> - }
> -
> - /* Last, determine what the bit-pattern should be for a single
> - device, according to chip mode and endianness... */
> - switch (chip_mode) {
> - case 1:
> - break;
> - case 2:
> - res = cfi16_to_cpu(map, res);
> - break;
> - case 4:
> - res = cfi32_to_cpu(map, res);
> - break;
> - default: BUG();
> - }
> - return res;
> -}
> -
> +unsigned long cfi_merge_status(map_word val, struct map_info *map,
> + struct cfi_private *cfi);
> #define MERGESTATUS(x) cfi_merge_status((x), map, cfi)
>
> -
> -/*
> - * Sends a CFI command to a bank of flash for the given geometry.
> - *
> - * Returns the offset in flash where the command was written.
> - * If prev_val is non-null, it will be set to the value at the command address,
> - * before the command was written.
> - */
> -static inline uint32_t cfi_send_gen_cmd(u_char cmd, uint32_t cmd_addr, uint32_t base,
> +uint32_t cfi_send_gen_cmd(u_char cmd, uint32_t cmd_addr, uint32_t base,
> struct map_info *map, struct cfi_private *cfi,
> - int type, map_word *prev_val)
> -{
> - map_word val;
> - uint32_t addr = base + cfi_build_cmd_addr(cmd_addr, map, cfi);
> - val = cfi_build_cmd(cmd, map, cfi);
> -
> - if (prev_val)
> - *prev_val = map_read(map, addr);
> -
> - map_write(map, val, addr);
> -
> - return addr - base;
> -}
> + int type, map_word *prev_val);
>
> static inline uint8_t cfi_read_query(struct map_info *map, uint32_t addr)
> {
> @@ -506,15 +342,7 @@ static inline uint16_t cfi_read_query16(struct map_info *map, uint32_t addr)
> }
> }
>
> -static inline void cfi_udelay(int us)
> -{
> - if (us >= 1000) {
> - msleep((us+999)/1000);
> - } else {
> - udelay(us);
> - cond_resched();
> - }
> -}
> +void cfi_udelay(int us);
>
> int __xipram cfi_qry_present(struct map_info *map, __u32 base,
> struct cfi_private *cfi);
> --
> 1.8.1.4
>
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