[RFC PATCH 2/2] modpost: use config and ELF sections to build file2alias
Dave Martin
dave.martin at linaro.org
Wed Nov 23 11:28:42 EST 2011
Taking a look at your original series...
On Tue, Nov 22, 2011 at 12:56:32PM +0100, Alessandro Rubini wrote:
[...]
> lkml.org/lkml/2011/11/4/125 (0/2: description of the work)
> lkml.org/lkml/2011/11/4/126 (1/2: turn the if plethora to table lookup)
> lkml.org/lkml/2011/11/4/127 (2/2: partial split to type-specific files).
I'm not the expert here, but I have a few comments that might be
useful.
On Fri, 4 Nov 2011 13:23:21 +0100, Alessandro Rubini <rubini at gnudd.com> wrote:
> diff --git a/scripts/mod/Makefile b/scripts/mod/Makefile
> index ff954f8..96c3b58 100644
> --- a/scripts/mod/Makefile
> +++ b/scripts/mod/Makefile
> @@ -1,7 +1,18 @@
> hostprogs-y := modpost mk_elfconfig
> always := $(hostprogs-y) empty.o
>
> -modpost-objs := modpost.o file2alias.o sumversion.o
> +# we can use bool or tristate options here
> +modpost-y := modpost.o file2alias.o sumversion.o
> +modpost-$(CONFIG_ACPI) += alias_acpi.o
> +modpost-$(CONFIG_BCMA) += alias_bcma.o
> +modpost-$(CONFIG_PCI) += alias_pci.o
> +modpost-$(CONFIG_SPI) += alias_spi.o
> +modpost-y += $(modpost-m)
> +
> +
> +modpost-objs += $(modpost-y)
> +
> +HOSTLDFLAGS := $(obj)/modpost.lds
>
> # dependencies on generated files need to be listed explicitly
>
> diff --git a/scripts/mod/alias_acpi.c b/scripts/mod/alias_acpi.c
> new file mode 100644
> index 0000000..acb6842
> --- /dev/null
> +++ b/scripts/mod/alias_acpi.c
> @@ -0,0 +1,14 @@
> +#include "modpost.h"
> +#include "device_switch.h"
> +
> +/* looks like: "acpi:ACPI0003 or acpi:PNP0C0B" or "acpi:LNXVIDEO" */
> +static int do_acpi_entry(const char *filename,
> + struct acpi_device_id *id, char *alias)
> +{
> + sprintf(alias, "acpi*:%s:*", id->id);
> + return 1;
> +}
> +
> +static struct devtable_switch dt_sw_acpi[] __DEVTABLE_SWITCH = {
> + E("acpi", "__mod_acpi_device_table", acpi_device_id, do_acpi_entry),
> +};
In files which define multiple bus types, there's no reason to put them
all in the same array, so we can avoid the explicit boilerplate.
Assuming this technique is used at all (see comments below), a modified
approach like the following would be possible:
device_switch.h:
#include <linux/compiler.h>
#define DEVTABLE_SWITCH(device_id, symname, structname, function) \
__DEVTABLE_SWITCH(__LINE__, device_id, symname, structname, function)
#define __DEVTABLE_SWITCH(line_num, device_id, symname, structname, function) \
static const struct devtable_swith __dt_sw_##device_id##_##line_num \
__section(.devtable.switch) __used = { \
.device_id = #device_id, \
.symname = symname, \
.id_size = sizeof(struct structname) \
.function = function \
}
__LINE__ is used simply to generate unique local symbol names in case a
file wants to define multiple entries. If we don't think that will ever
happen, that trick isn't needed.
At time of use, this just becomes:
#incluce "device_switch.h"
DEVTABLE_SWITCH(acpi, "__mod_acpi_device_table", acpi_device_id, do_acpi_entry);
Notwithstanding this, your version does look like it should work.
> diff --git a/scripts/mod/alias_bcma.c b/scripts/mod/alias_bcma.c
> new file mode 100644
> index 0000000..87fa860
> --- /dev/null
> +++ b/scripts/mod/alias_bcma.c
> @@ -0,0 +1,25 @@
> +
> +#include "modpost.h"
> +#include "device_switch.h"
> +
> +/* Looks like: bcma:mNidNrevNclN. */
> +static int do_bcma_entry(const char *filename,
> + struct bcma_device_id *id, char *alias)
> +{
> + id->manuf = TO_NATIVE(id->manuf);
> + id->id = TO_NATIVE(id->id);
> + id->rev = TO_NATIVE(id->rev);
> + id->class = TO_NATIVE(id->class);
> +
> + strcpy(alias, "bcma:");
> + ADD(alias, "m", id->manuf != BCMA_ANY_MANUF, id->manuf);
> + ADD(alias, "id", id->id != BCMA_ANY_ID, id->id);
> + ADD(alias, "rev", id->rev != BCMA_ANY_REV, id->rev);
> + ADD(alias, "cl", id->class != BCMA_ANY_CLASS, id->class);
> + add_wildcard(alias);
> + return 1;
> +}
> +
> +static struct devtable_switch dt_sw_bcma[] __DEVTABLE_SWITCH = {
> + E("bcma", "__mod_bcma_device_table", bcma_device_id, do_bcma_entry),
> +};
> diff --git a/scripts/mod/alias_pci.c b/scripts/mod/alias_pci.c
> new file mode 100644
> index 0000000..90f3a9a
> --- /dev/null
> +++ b/scripts/mod/alias_pci.c
> @@ -0,0 +1,49 @@
> +#include "modpost.h"
> +#include "device_switch.h"
> +
> +/* Looks like: pci:vNdNsvNsdNbcNscNiN. */
> +static int do_pci_entry(const char *filename,
> + struct pci_device_id *id, char *alias)
> +{
> + /* Class field can be divided into these three. */
> + unsigned char baseclass, subclass, interface,
> + baseclass_mask, subclass_mask, interface_mask;
> +
> + id->vendor = TO_NATIVE(id->vendor);
> + id->device = TO_NATIVE(id->device);
> + id->subvendor = TO_NATIVE(id->subvendor);
> + id->subdevice = TO_NATIVE(id->subdevice);
> + id->class = TO_NATIVE(id->class);
> + id->class_mask = TO_NATIVE(id->class_mask);
> +
> + strcpy(alias, "pci:");
> + ADD(alias, "v", id->vendor != PCI_ANY_ID, id->vendor);
> + ADD(alias, "d", id->device != PCI_ANY_ID, id->device);
> + ADD(alias, "sv", id->subvendor != PCI_ANY_ID, id->subvendor);
> + ADD(alias, "sd", id->subdevice != PCI_ANY_ID, id->subdevice);
> +
> + baseclass = (id->class) >> 16;
> + baseclass_mask = (id->class_mask) >> 16;
> + subclass = (id->class) >> 8;
> + subclass_mask = (id->class_mask) >> 8;
> + interface = id->class;
> + interface_mask = id->class_mask;
> +
> + if ((baseclass_mask != 0 && baseclass_mask != 0xFF)
> + || (subclass_mask != 0 && subclass_mask != 0xFF)
> + || (interface_mask != 0 && interface_mask != 0xFF)) {
> + warn("Can't handle masks in %s:%04X\n",
> + filename, id->class_mask);
> + return 0;
> + }
> +
> + ADD(alias, "bc", baseclass_mask == 0xFF, baseclass);
> + ADD(alias, "sc", subclass_mask == 0xFF, subclass);
> + ADD(alias, "i", interface_mask == 0xFF, interface);
> + add_wildcard(alias);
> + return 1;
> +}
> +
> +static struct devtable_switch dt_sw_pci[] __DEVTABLE_SWITCH = {
> + E("pci", "__mod_pci_device_table", pci_device_id, do_pci_entry),
> +};
> diff --git a/scripts/mod/alias_spi.c b/scripts/mod/alias_spi.c
> new file mode 100644
> index 0000000..d509820
> --- /dev/null
> +++ b/scripts/mod/alias_spi.c
> @@ -0,0 +1,15 @@
> +#include "modpost.h"
> +#include "device_switch.h"
> +
> +/* Looks like: spi:S */
> +static int do_spi_entry(const char *filename, struct spi_device_id *id,
> + char *alias)
> +{
> + sprintf(alias, SPI_MODULE_PREFIX "%s", id->name);
> +
> + return 1;
> +}
> +
> +static struct devtable_switch dt_sw_spi[] __DEVTABLE_SWITCH = {
> + E("spi", "__mod_spi_device_table", spi_device_id, do_spi_entry),
> +};
> diff --git a/scripts/mod/device_switch.h b/scripts/mod/device_switch.h
> new file mode 100644
> index 0000000..9443cd5
> --- /dev/null
> +++ b/scripts/mod/device_switch.h
> @@ -0,0 +1,47 @@
> +/* We use the ELF typedefs for kernel_ulong_t but bite the bullet and
> + * use either stdint.h or inttypes.h for the rest. */
> +#if KERNEL_ELFCLASS == ELFCLASS32
> +typedef Elf32_Addr kernel_ulong_t;
> +#define BITS_PER_LONG 32
> +#else
> +typedef Elf64_Addr kernel_ulong_t;
> +#define BITS_PER_LONG 64
> +#endif
> +#ifdef __sun__
> +#include <inttypes.h>
> +#else
> +#include <stdint.h>
> +#endif
> +
> +#include <ctype.h>
> +
> +typedef uint32_t __u32;
> +typedef uint16_t __u16;
> +typedef unsigned char __u8;
> +
> +/* Big exception to the "don't include kernel headers into userspace, which
> + * even potentially has different endianness and word sizes, since
> + * we handle those differences explicitly below */
> +#include "../../include/linux/mod_devicetable.h"
> +
> +#define ADD(str, sep, cond, field) \
> +do { \
> + strcat(str, sep); \
> + if (cond) \
> + sprintf(str + strlen(str), \
> + sizeof(field) == 1 ? "%02X" : \
> + sizeof(field) == 2 ? "%04X" : \
> + sizeof(field) == 4 ? "%08X" : "", \
> + field); \
> + else \
> + sprintf(str + strlen(str), "*"); \
> +} while(0)
> +
> +/* Always end in a wildcard, for future extension */
> +static inline void add_wildcard(char *str)
> +{
> + int len = strlen(str);
> +
> + if (str[len - 1] != '*')
> + strcat(str + len, "*");
> +}
> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> index 1247bc9..8e91fe4 100644
> --- a/scripts/mod/file2alias.c
> +++ b/scripts/mod/file2alias.c
> @@ -11,54 +11,7 @@
> */
>
> #include "modpost.h"
> -
> -/* We use the ELF typedefs for kernel_ulong_t but bite the bullet and
> - * use either stdint.h or inttypes.h for the rest. */
> -#if KERNEL_ELFCLASS == ELFCLASS32
> -typedef Elf32_Addr kernel_ulong_t;
> -#define BITS_PER_LONG 32
> -#else
> -typedef Elf64_Addr kernel_ulong_t;
> -#define BITS_PER_LONG 64
> -#endif
> -#ifdef __sun__
> -#include <inttypes.h>
> -#else
> -#include <stdint.h>
> -#endif
> -
> -#include <ctype.h>
> -
> -typedef uint32_t __u32;
> -typedef uint16_t __u16;
> -typedef unsigned char __u8;
> -
> -/* Big exception to the "don't include kernel headers into userspace, which
> - * even potentially has different endianness and word sizes, since
> - * we handle those differences explicitly below */
> -#include "../../include/linux/mod_devicetable.h"
> -
> -#define ADD(str, sep, cond, field) \
> -do { \
> - strcat(str, sep); \
> - if (cond) \
> - sprintf(str + strlen(str), \
> - sizeof(field) == 1 ? "%02X" : \
> - sizeof(field) == 2 ? "%04X" : \
> - sizeof(field) == 4 ? "%08X" : "", \
> - field); \
> - else \
> - sprintf(str + strlen(str), "*"); \
> -} while(0)
> -
> -/* Always end in a wildcard, for future extension */
> -static inline void add_wildcard(char *str)
> -{
> - int len = strlen(str);
> -
> - if (str[len - 1] != '*')
> - strcat(str + len, "*");
> -}
> +#include "device_switch.h"
>
> unsigned int cross_build = 0;
> /**
> @@ -314,49 +267,6 @@ static int do_ieee1394_entry(const char *filename,
> return 1;
> }
>
> -/* Looks like: pci:vNdNsvNsdNbcNscNiN. */
> -static int do_pci_entry(const char *filename,
> - struct pci_device_id *id, char *alias)
> -{
> - /* Class field can be divided into these three. */
> - unsigned char baseclass, subclass, interface,
> - baseclass_mask, subclass_mask, interface_mask;
> -
> - id->vendor = TO_NATIVE(id->vendor);
> - id->device = TO_NATIVE(id->device);
> - id->subvendor = TO_NATIVE(id->subvendor);
> - id->subdevice = TO_NATIVE(id->subdevice);
> - id->class = TO_NATIVE(id->class);
> - id->class_mask = TO_NATIVE(id->class_mask);
> -
> - strcpy(alias, "pci:");
> - ADD(alias, "v", id->vendor != PCI_ANY_ID, id->vendor);
> - ADD(alias, "d", id->device != PCI_ANY_ID, id->device);
> - ADD(alias, "sv", id->subvendor != PCI_ANY_ID, id->subvendor);
> - ADD(alias, "sd", id->subdevice != PCI_ANY_ID, id->subdevice);
> -
> - baseclass = (id->class) >> 16;
> - baseclass_mask = (id->class_mask) >> 16;
> - subclass = (id->class) >> 8;
> - subclass_mask = (id->class_mask) >> 8;
> - interface = id->class;
> - interface_mask = id->class_mask;
> -
> - if ((baseclass_mask != 0 && baseclass_mask != 0xFF)
> - || (subclass_mask != 0 && subclass_mask != 0xFF)
> - || (interface_mask != 0 && interface_mask != 0xFF)) {
> - warn("Can't handle masks in %s:%04X\n",
> - filename, id->class_mask);
> - return 0;
> - }
> -
> - ADD(alias, "bc", baseclass_mask == 0xFF, baseclass);
> - ADD(alias, "sc", subclass_mask == 0xFF, subclass);
> - ADD(alias, "i", interface_mask == 0xFF, interface);
> - add_wildcard(alias);
> - return 1;
> -}
> -
> /* looks like: "ccw:tNmNdtNdmN" */
> static int do_ccw_entry(const char *filename,
> struct ccw_device_id *id, char *alias)
> @@ -415,14 +325,6 @@ static int do_serio_entry(const char *filename,
> return 1;
> }
>
> -/* looks like: "acpi:ACPI0003 or acpi:PNP0C0B" or "acpi:LNXVIDEO" */
> -static int do_acpi_entry(const char *filename,
> - struct acpi_device_id *id, char *alias)
> -{
> - sprintf(alias, "acpi*:%s:*", id->id);
> - return 1;
> -}
> -
> /* looks like: "pnp:dD" */
> static void do_pnp_device_entry(void *symval, unsigned long size,
> struct module *mod)
> @@ -702,24 +604,6 @@ static int do_ssb_entry(const char *filename,
> return 1;
> }
>
> -/* Looks like: bcma:mNidNrevNclN. */
> -static int do_bcma_entry(const char *filename,
> - struct bcma_device_id *id, char *alias)
> -{
> - id->manuf = TO_NATIVE(id->manuf);
> - id->id = TO_NATIVE(id->id);
> - id->rev = TO_NATIVE(id->rev);
> - id->class = TO_NATIVE(id->class);
> -
> - strcpy(alias, "bcma:");
> - ADD(alias, "m", id->manuf != BCMA_ANY_MANUF, id->manuf);
> - ADD(alias, "id", id->id != BCMA_ANY_ID, id->id);
> - ADD(alias, "rev", id->rev != BCMA_ANY_REV, id->rev);
> - ADD(alias, "cl", id->class != BCMA_ANY_CLASS, id->class);
> - add_wildcard(alias);
> - return 1;
> -}
> -
> /* Looks like: virtio:dNvN */
> static int do_virtio_entry(const char *filename, struct virtio_device_id *id,
> char *alias)
> @@ -765,13 +649,14 @@ static int do_i2c_entry(const char *filename, struct i2c_device_id *id,
> return 1;
> }
>
> -/* Looks like: spi:S */
> -static int do_spi_entry(const char *filename, struct spi_device_id *id,
> - char *alias)
> +static void dmi_ascii_filter(char *d, const char *s)
> {
> - sprintf(alias, SPI_MODULE_PREFIX "%s", id->name);
> + /* Filter out characters we don't want to see in the modalias string */
> + for (; *s; s++)
> + if (*s > ' ' && *s < 127 && *s != ':')
> + *(d++) = *s;
>
> - return 1;
> + *d = 0;
> }
>
> static const struct dmifield {
> @@ -793,17 +678,6 @@ static const struct dmifield {
> { NULL, DMI_NONE }
> };
>
> -static void dmi_ascii_filter(char *d, const char *s)
> -{
> - /* Filter out characters we don't want to see in the modalias string */
> - for (; *s; s++)
> - if (*s > ' ' && *s < 127 && *s != ':')
> - *(d++) = *s;
> -
> - *d = 0;
> -}
> -
> -
> static int do_dmi_entry(const char *filename, struct dmi_system_id *id,
> char *alias)
> {
> @@ -891,7 +765,7 @@ static inline int sym_is(const char *symbol, const char *name)
> return match[strlen(name)] == '\0';
> }
>
> -static void do_table(void *symval, unsigned long size,
> +void do_table(void *symval, unsigned long size,
> unsigned long id_size,
> const char *device_id,
> void *function,
> @@ -913,17 +787,7 @@ static void do_table(void *symval, unsigned long size,
> }
> }
>
> -/* This array collects all instances that use the generic do_table above */
> -struct devtable_switch {
> - const char *device_id;
> - const char *symname;
> - unsigned long id_size;
> - void *function;
> -};
> -#define E(id, name, structname, f) {id, name, sizeof(struct structname), f}
> -
> -static struct devtable_switch devtable_switch[] = {
> - E("pci", "__mod_pci_device_table", pci_device_id, do_pci_entry),
> +static struct devtable_switch devtable_switch[] __DEVTABLE_SWITCH = {
> E("hid", "__mod_hid_device_table", hid_device_id, do_hid_entry),
> E("ieee1394", "__mod_ieee1394_device_table",
> ieee1394_device_id, do_ieee1394_entry),
> @@ -931,7 +795,6 @@ static struct devtable_switch devtable_switch[] = {
> E("ap", "__mod_ap_device_table", ap_device_id, do_ap_entry),
> E("css", "__mod_css_device_table", css_device_id, do_css_entry),
> E("seio", "__mod_serio_device_table", serio_device_id, do_serio_entry),
> - E("acpi", "__mod_acpi_device_table", acpi_device_id, do_acpi_entry),
> E("pcmcia", "__mod_pcmcia_device_table",
> pcmcia_device_id, do_pcmcia_entry),
> E("of", "__mod_of_device_table", of_device_id, do_of_entry),
> @@ -942,13 +805,11 @@ static struct devtable_switch devtable_switch[] = {
> parisc_device_id, do_parisc_entry),
> E("sdio", "__mod_sdio_device_table", sdio_device_id, do_sdio_entry),
> E("ssb", "__mod_ssb_device_table", ssb_device_id, do_ssb_entry),
> - E("bcma", "__mod_bcma_device_table", bcma_device_id, do_bcma_entry),
> E("virtio", "__mod_virtio_device_table",
> virtio_device_id, do_virtio_entry),
> E("vmbus", "__mod_vmbus_device_table",
> hv_vmbus_device_id, do_vmbus_entry),
> E("i2c", "__mod_i2c_device_table", i2c_device_id, do_i2c_entry),
> - E("spi", "__mod_spi_device_table", spi_device_id, do_spi_entry),
> E("dmi", "__mod_dmi_device_table", dmi_system_id, do_dmi_entry),
> E("platform", "__mod_platform_device_table",
> platform_device_id, do_platform_entry),
> @@ -989,11 +850,10 @@ void handle_moddevtable(struct module *mod, struct elf_info *info,
> else if (sym_is(symname, "__mod_pnp_card_device_table"))
> do_pnp_card_entries(symval, sym->st_size, mod);
> else {
> - struct devtable_switch *p = devtable_switch;
> - int i;
> + struct devtable_switch *p;
>
> /* scan the array */
> - for (i = 0; i < ARRAY_SIZE(devtable_switch); i++, p++) {
> + for (p = __dt_sw_first; p < __dt_sw_last; p++) {
> if (sym_is(symname, p->symname)) {
> do_table(symval, sym->st_size, p->id_size,
> p->device_id, p->function, mod);
> diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> index 2031119..ea98de3 100644
> --- a/scripts/mod/modpost.h
> +++ b/scripts/mod/modpost.h
> @@ -169,6 +169,24 @@ void handle_moddevtable(struct module *mod, struct elf_info *info,
> Elf_Sym *sym, const char *symname);
> void add_moddevtable(struct buffer *buf, struct module *mod);
>
> +void do_table(void *symval, unsigned long size,
> + unsigned long id_size,
> + const char *device_id,
> + void *function,
> + struct module *mod);
> +
> +/* An array of these is assembled at compile time */
> +struct devtable_switch {
> + const char *device_id;
> + const char *symname;
> + unsigned long id_size;
> + void *function;
> +};
> +#define E(id, name, structname, f) {id, name, sizeof(struct structname), f}
> +#define __DEVTABLE_SWITCH __attribute__((section(".devtable_switch"),used))
I have some misgivings about using this kind of toolchain trick where it
is not needed -- though this is partly a matter of taste.
(To clarify, I believe this technique isn't needed except when the
resulting tables need to be inspectable from a binary only
environment, such as the running kernel image or tools like modinfo.)
All we really need here is to include the required set of headers at
compile-time, rather than doing these link-time tricks. This is
essentially just a source transofmration and can probably be done
straightforwardly with an autogenerated include file, a couple of
Makefile rules and some scripting or preprocessor tricks to paste
the relevant entries into a common array.
If you think that's worth a try, we can discuss it further.
> +
> +extern struct devtable_switch __dt_sw_first[], __dt_sw_last[];
> +
> /* sumversion.c */
> void maybe_frob_rcs_version(const char *modfilename,
> char *version,
> diff --git a/scripts/mod/modpost.lds b/scripts/mod/modpost.lds
> new file mode 100644
> index 0000000..0642326
> --- /dev/null
> +++ b/scripts/mod/modpost.lds
> @@ -0,0 +1,9 @@
> +SECTIONS
> +{
> + .data : {
> + . = ALIGN(0x40);
> + __dt_sw_first = .;
> + *(.devtable_switch);
> + __dt_sw_last = .;
> + }
> +}
> --
> 1.6.0.2
>
>
For myself, I have some misgivings about using this kind of toolchain
trick where it is not needed -- though this is partly a matter of taste.
(To clarify, I think this stuff is only needed where the resulting
tables need to be inspectable from a binary-only environment, such
as in the running kernel, or when using kernel image analysis tools
which are not supposed to depend in having a configured kernel source
tree handy, such as modinfo.)
The problem to be solved here is essentially a source transofmration
and should be possible to do straightforwardly with an autogenerated
include file, a couple of Makefile rules and some scripting or
preprocessor tricks to paste the relevant entries into a common
array.
If you think that's worth a try, we can discuss it further.
> +
> +extern struct devtable_switch __dt_sw_first[], __dt_sw_last[];
> +
> /* sumversion.c */
> void maybe_frob_rcs_version(const char *modfilename,
> char *version,
> diff --git a/scripts/mod/modpost.lds b/scripts/mod/modpost.lds
> new file mode 100644
> index 0000000..0642326
> --- /dev/null
> +++ b/scripts/mod/modpost.lds
> @@ -0,0 +1,9 @@
> +SECTIONS
> +{
> + .data : {
> + . = ALIGN(0x40);
> + __dt_sw_first = .;
> + *(.devtable_switch);
> + __dt_sw_last = .;
> + }
> +}
> --
> 1.6.0.2
>
>
Otherwise, this series looks like a sensible evolution to me.
Cheers
---Dave
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