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Message-ID: <c5c8b57e-7954-ec02-188a-7f85cb0af731@csgroup.eu>
Date: Tue, 9 Mar 2021 08:56:47 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Daniel Walker <danielwa@...co.com>, 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>
Cc: 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 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.
> -
> -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 ?
> #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().
> 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.
>
> 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.
> mem_start = (unsigned long)namep + prom_strlen(namep) + 1;
>
> /* Build string array */
>
Christophe
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