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Message-ID: <9c5b8e33-026e-c9d6-c267-a5dd4a2b999c@csgroup.eu>
Date: Wed, 24 Mar 2021 16:31:35 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Daniel Walker <danielwa@...co.com>
Cc: Will Deacon <will@...nel.org>, Rob Herring <robh@...nel.org>,
Daniel Gimpelevich <daniel@...pelevich.san-francisco.ca.us>,
Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
xe-linux-external@...co.com, Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
Paul Mackerras <paulus@...ba.org>,
Ruslan Ruslichenko <rruslich@...co.com>,
Ruslan Bilovol <rbilovol@...co.com>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/7] CMDLINE: powerpc: convert to generic builtin
command line
Le 09/03/2021 à 22:40, Daniel Walker a écrit :
> On Tue, Mar 09, 2021 at 08:56:47AM +0100, Christophe Leroy wrote:
>>
>>
>> Le 09/03/2021 à 01:02, Daniel Walker a écrit :
>>> This updates the powerpc code to use the CONFIG_GENERIC_CMDLINE
>>> option.
>>>
>>> Cc: xe-linux-external@...co.com
>>> Signed-off-by: Ruslan Ruslichenko <rruslich@...co.com>
>>> Signed-off-by: Ruslan Bilovol <rbilovol@...co.com>
>>> Signed-off-by: Daniel Walker <danielwa@...co.com>
>>> ---
>>> arch/powerpc/Kconfig | 37 +--------------------------------
>>> arch/powerpc/kernel/prom.c | 1 +
>>> arch/powerpc/kernel/prom_init.c | 35 ++++++++++++++++++-------------
>>> 3 files changed, 23 insertions(+), 50 deletions(-)
>>>
>>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>>> index 107bb4319e0e..276b06d5c961 100644
>>> --- a/arch/powerpc/Kconfig
>>> +++ b/arch/powerpc/Kconfig
>>> @@ -167,6 +167,7 @@ config PPC
>>> select EDAC_SUPPORT
>>> select GENERIC_ATOMIC64 if PPC32
>>> select GENERIC_CLOCKEVENTS_BROADCAST if SMP
>>> + select GENERIC_CMDLINE
>>> select GENERIC_CMOS_UPDATE
>>> select GENERIC_CPU_AUTOPROBE
>>> select GENERIC_CPU_VULNERABILITIES if PPC_BARRIER_NOSPEC
>>> @@ -906,42 +907,6 @@ config PPC_DENORMALISATION
>>> Add support for handling denormalisation of single precision
>>> values. Useful for bare metal only. If unsure say Y here.
>>> -config CMDLINE
>>> - string "Initial kernel command string"
>>> - default ""
>>> - help
>>> - On some platforms, there is currently no way for the boot loader to
>>> - pass arguments to the kernel. For these platforms, you can supply
>>> - some command-line options at build time by entering them here. In
>>> - most cases you will need to specify the root device here.
>>> -
>>> -choice
>>> - prompt "Kernel command line type" if CMDLINE != ""
>>> - default CMDLINE_FROM_BOOTLOADER
>>> -
>>> -config CMDLINE_FROM_BOOTLOADER
>>> - bool "Use bootloader kernel arguments if available"
>>> - help
>>> - Uses the command-line options passed by the boot loader. If
>>> - the boot loader doesn't provide any, the default kernel command
>>> - string provided in CMDLINE will be used.
I can't see how the above is supported in the generic builtin.
Taking into account that it is the default on powerpc, I'm having hardtime with that.
>>> -
>>> -config CMDLINE_EXTEND
>>> - bool "Extend bootloader kernel arguments"
>>> - help
>>> - The command-line arguments provided by the boot loader will be
>>> - appended to the default kernel command string.
>>> -
>>> -config CMDLINE_FORCE
>>> - bool "Always use the default kernel command string"
>>> - help
>>> - Always use the default kernel command string, even if the boot
>>> - loader passes other arguments to the kernel.
>>> - This is useful if you cannot or don't want to change the
>>> - command-line options your boot loader passes to the kernel.
>>> -
>>> -endchoice
>>> -
>>> config EXTRA_TARGETS
>>> string "Additional default image types"
>>> help
>>> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
>>> index ae3c41730367..96d0a01be1b4 100644
>>> --- a/arch/powerpc/kernel/prom.c
>>> +++ b/arch/powerpc/kernel/prom.c
>>> @@ -27,6 +27,7 @@
>>> #include <linux/irq.h>
>>> #include <linux/memblock.h>
>>> #include <linux/of.h>
>>> +#include <linux/cmdline.h>
>>
>> Why is this needed in prom.c ?
>
> Must have been a mistake, I don't think it's needed.
>
>
>>> #include <linux/of_fdt.h>
>>> #include <linux/libfdt.h>
>>> #include <linux/cpu.h>
>>> diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
>>> index e9d4eb6144e1..657241534d69 100644
>>> --- a/arch/powerpc/kernel/prom_init.c
>>> +++ b/arch/powerpc/kernel/prom_init.c
>>> @@ -27,6 +27,7 @@
>>> #include <linux/initrd.h>
>>> #include <linux/bitops.h>
>>> #include <linux/pgtable.h>
>>> +#include <linux/cmdline.h>
>>> #include <asm/prom.h>
>>> #include <asm/rtas.h>
>>> #include <asm/page.h>
>>> @@ -242,15 +243,6 @@ static int __init prom_strcmp(const char *cs, const char *ct)
>>> return 0;
>>> }
>>> -static char __init *prom_strcpy(char *dest, const char *src)
>>> -{
>>> - char *tmp = dest;
>>> -
>>> - while ((*dest++ = *src++) != '\0')
>>> - /* nothing */;
>>> - return tmp;
>>> -}
>>> -
>>
>> This game with prom_strcpy() should go a separate preceeding patch.
>>
>> Also, it looks like checkpatch.pl recommends to use strscpy() instead of strlcpy().
>
> strscpy() is very large. I'm not sure it's compatible with this prom_init.c
> environment.
Ok you are right, lets keep strlcpy() and ignore checkpatch complaints
>
>>> static int __init prom_strncmp(const char *cs, const char *ct, size_t count)
>>> {
>>> unsigned char c1, c2;
>>> @@ -276,6 +268,20 @@ static size_t __init prom_strlen(const char *s)
>>> return sc - s;
>>> }
>>> +static size_t __init prom_strlcpy(char *dest, const char *src, size_t size)
>>> +{
>>> + size_t ret = prom_strlen(src);
>>> +
>>> + if (size) {
>>> + size_t len = (ret >= size) ? size - 1 : ret;
>>> +
>>> + memcpy(dest, src, len);
>>> + dest[len] = '\0';
>>> + }
>>> + return ret;
>>> +}
>>> +
>>> +
>>> static int __init prom_memcmp(const void *cs, const void *ct, size_t count)
>>> {
>>> const unsigned char *su1, *su2;
>>> @@ -304,6 +310,7 @@ static char __init *prom_strstr(const char *s1, const char *s2)
>>> return NULL;
>>> }
>>> +#ifdef GENERIC_CMDLINE_NEED_STRLCAT
>>> static size_t __init prom_strlcat(char *dest, const char *src, size_t count)
>>> {
>>> size_t dsize = prom_strlen(dest);
>>> @@ -323,6 +330,7 @@ static size_t __init prom_strlcat(char *dest, const char *src, size_t count)
>>> return res;
>>> }
>>> +#endif
>>> #ifdef CONFIG_PPC_PSERIES
>>> static int __init prom_strtobool(const char *s, bool *res)
>>> @@ -775,12 +783,11 @@ static void __init early_cmdline_parse(void)
>>> prom_cmd_line[0] = 0;
>>> p = prom_cmd_line;
>>> - if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && (long)prom.chosen > 0)
>>> + if ((long)prom.chosen > 0)
>>> l = prom_getprop(prom.chosen, "bootargs", p, COMMAND_LINE_SIZE-1);
>>> - if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || l <= 0 || p[0] == '\0')
>>> - prom_strlcat(prom_cmd_line, " " CONFIG_CMDLINE,
>>> - sizeof(prom_cmd_line));
>>> + cmdline_add_builtin_custom(prom_cmd_line, (l > 0 ? p : NULL), sizeof(prom_cmd_line),
>>> + __prombss, prom_strlcpy, prom_strlcat);
>>
>> So we are referencing a function that doesn't exist (namely prom_strlcat).
>> But it works because cmdline_add_builtin_custom() looks like a function but
>> is in fact an obscure macro that doesn't use prom_strlcat() unless
>> GENERIC_CMDLINE_NEED_STRLCAT is defined.
>>
>> IMHO that's awful for readability and code maintenance.
>
> powerpc is a special case, there's no other users like this. The reason is
> because of all the difficulty in this prom_init.c code. A lot of the generic
> code has similar kind of changes to work across architectures.
Any feedback on the proposed changes I made on the 13th ? I know it is partly buggy but that was
more for the principle. I can make clean working patch if it helps.
>
>
>>> prom_printf("command line: %s\n", prom_cmd_line);
>>> @@ -2706,7 +2713,7 @@ static void __init flatten_device_tree(void)
>>> /* Add "phandle" in there, we'll need it */
>>> namep = make_room(&mem_start, &mem_end, 16, 1);
>>> - prom_strcpy(namep, "phandle");
>>> + prom_strlcpy(namep, "phandle", 8);
>>
>> Should be in a separate patch.
>
> I can move it, I missed that from the first round.
>
> Daniel
>
Christophe
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