Messages in this thread Patch in this message |  | | Date | Tue, 4 Feb 2020 07:28:56 -0500 | From | Steven Rostedt <> | Subject | Re: [GIT PULL] tracing: Changes for 5.6 |
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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();
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