From: Steven Rostedt <rostedt@goodmis.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
Tom Zanussi <zanussi@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [GIT PULL] tracing: Changes for 5.6
Date: Tue, 4 Feb 2020 07:28:56 -0500 [thread overview]
Message-ID: <20200204072856.0da60613@oasis.local.home> (raw)
In-Reply-To: <CAHk-=wjfjO+h6bQzrTf=YCZA53Y3EDyAs3Z4gEsT7icA3u_Psw@mail.gmail.com>
On Tue, 4 Feb 2020 11:54:09 +0000
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Tue, Feb 4, 2020 at 10:32 AM Steven Rostedt <rostedt@goodmis.org> wrote:
> >
> > - Added new "bootconfig".
> > Looks for a file appended to initrd to add boot config options.
> > This has been discussed thoroughly at Linux Plumbers.
> > Very useful for adding kprobes at bootup.
>
> Is there a way to disable this from the "real" kernel command line?
Currently no.
>
> If I have problems, I want to boot with a known kernel command line
> (forcing text mode etc). If the bootconfig file always gets parsed,
> there's no way to do that from the bootloader (grub2, whatever)..
>
I totally agree as I had that exact same issue while testing this. I
wanted to not have it and found it a bit annoying I needed to modify
the initrd to remove it for just a single boot up.
Would this work?
-- Steve
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index ade4e6ec23e0..c4f1417f1934 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -857,6 +857,10 @@
on Perform hardened usercopy checks (default).
off Disable hardened usercopy checks.
+ disable_bootconfig
+ Disable reading the bootconfig that may be attached
+ to the initrd.
+
disable_radix [PPC]
Disable RADIX MMU mode on POWER9
diff --git a/init/main.c b/init/main.c
index dd7da62d99a5..b52636cd9c1d 100644
--- a/init/main.c
+++ b/init/main.c
@@ -336,15 +336,23 @@ u32 boot_config_checksum(unsigned char *p, u32 size)
return ret;
}
-static void __init setup_boot_config(void)
+static void __init setup_boot_config(const char *cmdline)
{
u32 size, csum;
char *data, *copy;
+ const char *p;
u32 *hdr;
if (!initrd_end)
return;
+ p = strstr(cmdline, "disable_bootconfig");
+ if (p && (p == cmdline || isspace(*(p-1))) &&
+ (!p[18] || isspace(p[18]))) {
+ pr_info("Disabling bootconfig because 'disable_bootconfig' found on the command line\n");
+ return;
+ }
+
hdr = (u32 *)(initrd_end - 8);
size = hdr[0];
csum = hdr[1];
@@ -379,7 +387,7 @@ static void __init setup_boot_config(void)
}
}
#else
-#define setup_boot_config() do { } while (0)
+#define setup_boot_config(cmdline) do { } while (0)
#endif
/* Change NUL term back to "=", to make "param" the whole string. */
@@ -760,7 +768,7 @@ asmlinkage __visible void __init start_kernel(void)
pr_notice("%s", linux_banner);
early_security_init();
setup_arch(&command_line);
- setup_boot_config();
+ setup_boot_config(command_line);
setup_command_line(command_line);
setup_nr_cpu_ids();
setup_per_cpu_areas();
next prev parent reply other threads:[~2020-02-04 12:29 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-04 10:31 [GIT PULL] tracing: Changes for 5.6 Steven Rostedt
2020-02-04 11:54 ` Linus Torvalds
2020-02-04 12:28 ` Steven Rostedt [this message]
2020-02-04 12:43 ` [PATCH] bootconfig: Add "disable_bootconfig" cmdline option to disable bootconfig Steven Rostedt
2020-02-04 13:19 ` [GIT PULL] tracing: Changes for 5.6 Linus Torvalds
2020-02-04 13:46 ` Steven Rostedt
2020-02-04 14:25 ` [PATCH v2] bootconfig: Only load bootconfig if "config=bootconfig" is on the kernel cmdline (was: bootconfig: Add "disable_bootconfig" cmdline option to disable bootconfig) Steven Rostedt
2020-02-04 14:33 ` Steven Rostedt
2020-02-04 15:43 ` Linus Torvalds
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