Re: [PATCH 6/8] drivers: firmware: efi: libstub: enable generic commandline

[Daniel Walker <danielwa@cisco.com>]

On Fri, Apr 02, 2021 at 07:36:53PM +0200, Christophe Leroy wrote:
> 
> 
> Le 30/03/2021 à 19:57, Daniel Walker a écrit :
> > This adds code to handle the generic command line changes.
> > The efi code appears that it doesn't benefit as much from this design
> > as it could.
> > 
> > For example, if you had a prepend command line with "nokaslr" then
> > you might be helpful to re-enable it in the boot loader or dts,
> > but there appears to be no way to re-enable kaslr or some of the
> > other options.
> > 
> > Cc: xe-linux-external@cisco.com
> > Signed-off-by: Daniel Walker <danielwa@cisco.com>
> > ---
> >   .../firmware/efi/libstub/efi-stub-helper.c    | 35 +++++++++++++++++++
> >   drivers/firmware/efi/libstub/efi-stub.c       |  7 ++++
> >   drivers/firmware/efi/libstub/efistub.h        |  1 +
> >   drivers/firmware/efi/libstub/x86-stub.c       | 13 +++++--
> >   4 files changed, 54 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
> > index aa8da0a49829..c155837cedc9 100644
> > --- a/drivers/firmware/efi/libstub/efi-stub-helper.c
> > +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
> > @@ -13,6 +13,7 @@
> >   #include <linux/efi.h>
> >   #include <linux/kernel.h>
> >   #include <linux/printk.h> /* For CONSOLE_LOGLEVEL_* */
> > +#include <linux/cmdline.h>
> >   #include <asm/efi.h>
> >   #include <asm/setup.h>
> > @@ -172,6 +173,40 @@ int efi_printk(const char *fmt, ...)
> >   	return printed;
> >   }
> > +/**
> > + * efi_handle_cmdline() - handle adding in building parts of the command line
> > + * @cmdline:	kernel command line
> > + *
> > + * Add in the generic parts of the commandline and start the parsing of the
> > + * command line.
> > + *
> > + * Return:	status code
> > + */
> > +efi_status_t efi_handle_cmdline(char const *cmdline)
> > +{
> > +	efi_status_t status;
> > +
> > +	status = efi_parse_options(CMDLINE_PREPEND);
> > +	if (status != EFI_SUCCESS) {
> > +		efi_err("Failed to parse options\n");
> > +		return status;
> > +	}
> > +
> > +	status = efi_parse_options(IS_ENABLED(CONFIG_CMDLINE_OVERRIDE) ? "" : cmdline);
> > +	if (status != EFI_SUCCESS) {
> > +		efi_err("Failed to parse options\n");
> > +		return status;
> > +	}
> > +
> > +	status = efi_parse_options(CMDLINE_APPEND);
> > +	if (status != EFI_SUCCESS) {
> > +		efi_err("Failed to parse options\n");
> > +		return status;
> > +	}
> > +
> > +	return EFI_SUCCESS;
> > +}
> 
> I think we can refactor to first build the final command line, then call
> efi_parse_options() only once after that.
 
I tried this, like what you did in your v4 .. The issues are similar to the
prom_init.c problems. The environment is delicate and requires careful
programming to get it done correctly.

> The big advantage of GENERIC_CMDLINE should be to not address anymore
> CONFIG_CMDLINE_XXX options at all outside of linux/cmdline.h
 
I agree , but not I've found that it's not likely to get this all changed in a
single series.

Daniel