linux-kernel - Re: [PATCH v3] powerpc: Support CMDLINE

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Message-ID: <46da00814535270a2b525de1f75afc79f3abbf5c.camel@alliedtelesis.co.nz>
Date:   Thu, 7 Nov 2019 03:18:19 +0000
From:   Chris Packham <Chris.Packham@...iedtelesis.co.nz>
To:     "christophe.leroy@....fr" <christophe.leroy@....fr>,
        "paulus@...ba.org" <paulus@...ba.org>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>,
        "malat@...ian.org" <malat@...ian.org>
CC:     "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3] powerpc: Support CMDLINE_EXTEND

Hi All,

On Fri, 2019-08-02 at 06:40 +0200, Christophe Leroy wrote:
> 
> Le 02/08/2019 à 00:50, Chris Packham a écrit :
> > Bring powerpc in line with other architectures that support extending or
> > overriding the bootloader provided command line.
> > 
> > The current behaviour is most like CMDLINE_FROM_BOOTLOADER where the
> > bootloader command line is preferred but the kernel config can provide a
> > fallback so CMDLINE_FROM_BOOTLOADER is the default. CMDLINE_EXTEND can
> > be used to append the CMDLINE from the kernel config to the one provided
> > by the bootloader.
> > 
> > Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
> 
> Reviewed-by: Christophe Leroy <christophe.leroy@....fr>

Just going over some old patches this doesn't appear to be in next. Is
there anything stopping it from being accepted?

> 
> > ---
> > Changes in v3:
> > - don't use BUG_ON in prom_strlcat
> > - rearrange things to eliminate prom_strlcpy
> > 
> > Changes in v2:
> > - incorporate ideas from Christope's patch https://patchwork.ozlabs.org/patch/1074126/
> > - support CMDLINE_FORCE
> > 
> >   arch/powerpc/Kconfig            | 20 +++++++++++++++++-
> >   arch/powerpc/kernel/prom_init.c | 36 ++++++++++++++++++++++-----------
> >   2 files changed, 43 insertions(+), 13 deletions(-)
> > 
> > diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> > index 77f6ebf97113..d413fe1b4058 100644
> > --- a/arch/powerpc/Kconfig
> > +++ b/arch/powerpc/Kconfig
> > @@ -852,15 +852,33 @@ config CMDLINE
> >   	  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"
> > -	depends on CMDLINE_BOOL
> >   	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_init.c b/arch/powerpc/kernel/prom_init.c
> > index 514707ef6779..1c7010cc6ec9 100644
> > --- a/arch/powerpc/kernel/prom_init.c
> > +++ b/arch/powerpc/kernel/prom_init.c
> > @@ -298,16 +298,24 @@ static char __init *prom_strstr(const char *s1, const char *s2)
> >   	return NULL;
> >   }
> >   
> > -static size_t __init prom_strlcpy(char *dest, const char *src, size_t size)
> > -{
> > -	size_t ret = prom_strlen(src);
> > +static size_t __init prom_strlcat(char *dest, const char *src, size_t count)
> > +{
> > +	size_t dsize = prom_strlen(dest);
> > +	size_t len = prom_strlen(src);
> > +	size_t res = dsize + len;
> > +
> > +	/* This would be a bug */
> > +	if (dsize >= count)
> > +		return count;
> > +
> > +	dest += dsize;
> > +	count -= dsize;
> > +	if (len >= count)
> > +		len = count-1;
> > +	memcpy(dest, src, len);
> > +	dest[len] = 0;
> > +	return res;
> >   
> > -	if (size) {
> > -		size_t len = (ret >= size) ? size - 1 : ret;
> > -		memcpy(dest, src, len);
> > -		dest[len] = '\0';
> > -	}
> > -	return ret;
> >   }
> >   
> >   #ifdef CONFIG_PPC_PSERIES
> > @@ -759,10 +767,14 @@ static void __init early_cmdline_parse(void)
> >   
> >   	prom_cmd_line[0] = 0;
> >   	p = prom_cmd_line;
> > -	if ((long)prom.chosen > 0)
> > +
> > +	if (!IS_ENABLED(CONFIG_CMDLINE_FORCE) && (long)prom.chosen > 0)
> >   		l = prom_getprop(prom.chosen, "bootargs", p, COMMAND_LINE_SIZE-1);
> > -	if (IS_ENABLED(CONFIG_CMDLINE_BOOL) && (l <= 0 || p[0] == '\0')) /* dbl check */
> > -		prom_strlcpy(prom_cmd_line, CONFIG_CMDLINE, sizeof(prom_cmd_line));
> > +
> > +	if (IS_ENABLED(CONFIG_CMDLINE_EXTEND) || l <= 0 || p[0] == '\0')
> > +		prom_strlcat(prom_cmd_line, " " CONFIG_CMDLINE,
> > +			     sizeof(prom_cmd_line));
> > +
> >   	prom_printf("command line: %s\n", prom_cmd_line);
> >   
> >   #ifdef CONFIG_PPC64
> >