[PATCH] Add commands for reading and writing raw bytes to CMOS

[PATCH] Add commands for reading and writing raw bytes to CMOS

[Vladimir 'phcoder' Serbinenko]

[-- Attachment #1: Type: text/plain, Size: 285 bytes --]

With some coreboot configs setting a byte to a magic value
changes behaviour on next boot. Setting bit-by-bit is
possible but not convenient. Add cmosread and cmoswrite for
convenience.

Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>

-- 
Regards
Vladimir 'phcoder' Serbinenko

[-- Attachment #2: 0001-Add-commands-for-reading-and-writing-raw-bytes-to-CM.patch --]
[-- Type: application/octet-stream, Size: 3823 bytes --]

From a29cfa77e292fdd0792eeb0bc2a0287524c1de1f Mon Sep 17 00:00:00 2001
From: Vladimir Serbinenko <phcoder@gmail.com>
Date: Mon, 18 Sep 2023 02:20:13 +0200
Subject: [PATCH] Add commands for reading and writing raw bytes to CMOS

With some coreboot configs setting a byte to a magic value
changes behaviour on next boot. Setting bit-by-bit is
possible but not convenient. Add cmosread and cmoswrite for
convenience.

Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
---
 grub-core/commands/i386/cmostest.c | 77 +++++++++++++++++++++++++++++-
 1 file changed, 76 insertions(+), 1 deletion(-)

diff --git a/grub-core/commands/i386/cmostest.c b/grub-core/commands/i386/cmostest.c
index 1f0c5341d..920cd81eb 100644
--- a/grub-core/commands/i386/cmostest.c
+++ b/grub-core/commands/i386/cmostest.c
@@ -18,9 +18,12 @@
 
 #include <grub/dl.h>
 #include <grub/command.h>
+#include <grub/extcmd.h>
 #include <grub/misc.h>
 #include <grub/cmos.h>
 #include <grub/i18n.h>
+#include <grub/mm.h>
+#include <grub/env.h>
 
 GRUB_MOD_LICENSE ("GPLv3+");
 
@@ -99,7 +102,71 @@ grub_cmd_cmosset (struct grub_command *cmd __attribute__ ((unused)),
   return grub_cmos_write (byte, value | (1 << bit));
 }
 
-static grub_command_t cmd, cmd_clean, cmd_set;
+static grub_err_t
+grub_cmd_cmoswrite (struct grub_command *cmd __attribute__ ((unused)),
+		    int argc, char *argv[])
+{
+  int byte = -1, value = -1;
+
+  if (argc != 2)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("two arguments expected"));
+
+  byte = grub_strtoul (argv[0], NULL, 0);
+  if (grub_errno)
+    return grub_errno;
+
+  if (byte < 0 || byte >= 0x100)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid address"));
+
+  value = grub_strtoul (argv[1], NULL, 0);
+  if (grub_errno)
+    return grub_errno;
+
+  if (value < 0 || value >= 0x100)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid value"));
+
+  return grub_cmos_write (byte, value);
+}
+
+static grub_err_t
+grub_cmd_cmosread (grub_extcmd_context_t ctxt, int argc, char **argv)
+{
+  int byte = -1;
+  grub_uint8_t value = 0;
+  grub_err_t err;
+
+  if (argc != 1)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("one argument expected"));
+
+  byte = grub_strtoul (argv[0], NULL, 0);
+  if (grub_errno)
+    return grub_errno;
+
+  if (byte < 0 || byte >= 0x100)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid address"));
+
+  err = grub_cmos_read (byte, &value);
+  if (err)
+    return err;
+
+  if (ctxt->state[2].set) {
+    char buf[sizeof ("XX")];
+    grub_snprintf (buf, sizeof (buf), "%x", value);
+    grub_env_set(ctxt->state[2].arg, buf);
+  } else
+    grub_printf_("CMOS value at 0x%x is 0x%x\n", byte, value);
+  return GRUB_ERR_NONE;
+}
+
+static const struct grub_arg_option read_options[] =
+  {
+    {0, 'v', 0, N_("Save read value into variable VARNAME."),
+     N_("VARNAME"), ARG_TYPE_STRING},
+    {0, 0, 0, 0, 0, 0}
+  };
+
+static grub_command_t cmd, cmd_clean, cmd_set, cmd_write;
+static grub_extcmd_t cmd_read;
 
 \f
 GRUB_MOD_INIT(cmostest)
@@ -114,6 +181,12 @@ GRUB_MOD_INIT(cmostest)
 				   N_("BYTE:BIT"),
 				   /* TRANSLATORS: A bit may be either set (1) or clear (0).  */
 				   N_("Set bit at BYTE:BIT in CMOS."));
+  cmd_read = grub_register_extcmd_lockdown ("cmosread", grub_cmd_cmosread, 0,
+				       N_("[-v VAR] ADDR"),
+				       N_("Read CMOS byte at ADDR."), read_options);
+  cmd_write = grub_register_command_lockdown ("cmoswrite", grub_cmd_cmoswrite,
+					      N_("ADDR VALUE"),
+					      N_("Set CMOS byte at ADDR to VALUE."));
 }
 
 GRUB_MOD_FINI(cmostest)
@@ -121,4 +194,6 @@ GRUB_MOD_FINI(cmostest)
   grub_unregister_command (cmd);
   grub_unregister_command (cmd_clean);
   grub_unregister_command (cmd_set);
+  grub_unregister_extcmd (cmd_read);
+  grub_unregister_command (cmd_write);
 }
-- 
2.39.2


[-- Attachment #3: Type: text/plain, Size: 141 bytes --]

_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel

Re: [PATCH] Add commands for reading and writing raw bytes to CMOS

[Glenn Washburn]

On Fri, 15 Mar 2024 22:45:53 +0300
"Vladimir 'phcoder' Serbinenko" <phcoder@gmail.com> wrote:

> With some coreboot configs setting a byte to a magic value
> changes behaviour on next boot. Setting bit-by-bit is
> possible but not convenient. Add cmosread and cmoswrite for
> convenience.
> 
> Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
> 

Small nit, I think its customary to use '-s' in commands for setting
variables. '-v' would intuitively be for verbosity. Also, it would be
nice if you permanently configure your system to send patches as inline
and not as attachments. Are you not using git-send?

Glenn

_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel

Re: [PATCH] Add commands for reading and writing raw bytes to CMOS

[Daniel Kiper]

On Wed, Apr 03, 2024 at 04:59:57PM -0500, Glenn Washburn wrote:
> On Fri, 15 Mar 2024 22:45:53 +0300
> "Vladimir 'phcoder' Serbinenko" <phcoder@gmail.com> wrote:
>
> > With some coreboot configs setting a byte to a magic value
> > changes behaviour on next boot. Setting bit-by-bit is
> > possible but not convenient. Add cmosread and cmoswrite for
> > convenience.
> >
> > Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
> >
>
> Small nit, I think its customary to use '-s' in commands for setting
> variables. '-v' would intuitively be for verbosity. Also, it would be

I agree with Glenn.

> nice if you permanently configure your system to send patches as inline
> and not as attachments. Are you not using git-send?

I concur...

> From a29cfa77e292fdd0792eeb0bc2a0287524c1de1f Mon Sep 17 00:00:00 2001
> From: Vladimir Serbinenko <phcoder@gmail.com>
> Date: Mon, 18 Sep 2023 02:20:13 +0200
> Subject: [PATCH] Add commands for reading and writing raw bytes to CMOS
>
> With some coreboot configs setting a byte to a magic value
> changes behaviour on next boot. Setting bit-by-bit is
> possible but not convenient. Add cmosread and cmoswrite for
> convenience.
>
> Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
> ---
>  grub-core/commands/i386/cmostest.c | 77 +++++++++++++++++++++++++++++-
>  1 file changed, 76 insertions(+), 1 deletion(-)
>
> diff --git a/grub-core/commands/i386/cmostest.c b/grub-core/commands/i386/cmostest.c
> index 1f0c5341d..920cd81eb 100644
> --- a/grub-core/commands/i386/cmostest.c
> +++ b/grub-core/commands/i386/cmostest.c
> @@ -18,9 +18,12 @@
>
>  #include <grub/dl.h>
>  #include <grub/command.h>
> +#include <grub/extcmd.h>
>  #include <grub/misc.h>
>  #include <grub/cmos.h>
>  #include <grub/i18n.h>
> +#include <grub/mm.h>
> +#include <grub/env.h>
>
>  GRUB_MOD_LICENSE ("GPLv3+");
>
> @@ -99,7 +102,71 @@ grub_cmd_cmosset (struct grub_command *cmd __attribute__ ((unused)),
>    return grub_cmos_write (byte, value | (1 << bit));
>  }
>
> -static grub_command_t cmd, cmd_clean, cmd_set;
> +static grub_err_t
> +grub_cmd_cmoswrite (struct grub_command *cmd __attribute__ ((unused)),
> +		    int argc, char *argv[])
> +{
> +  int byte = -1, value = -1;

The byte and value should be defined as an unsigned long.

> +
> +  if (argc != 2)
> +    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("two arguments expected"));
> +
> +  byte = grub_strtoul (argv[0], NULL, 0);
> +  if (grub_errno)

In general I think we should not use shortened checks for enums and NULL.
Even if they work...

> +    return grub_errno;

AFAICT the grub_errno is not reliable here. The good example how the
grub_strtoul() result should be checked is in the commit ac8a37dda
(net/http: Allow use of non-standard TCP/IP ports).

> +  if (byte < 0 || byte >= 0x100)
> +    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid address"));
> +
> +  value = grub_strtoul (argv[1], NULL, 0);

Ditto and below please...

> +  if (grub_errno)
> +    return grub_errno;
> +
> +  if (value < 0 || value >= 0x100)
> +    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid value"));
> +
> +  return grub_cmos_write (byte, value);
> +}
> +
> +static grub_err_t
> +grub_cmd_cmosread (grub_extcmd_context_t ctxt, int argc, char **argv)

Could you put this function before grub_cmd_cmoswrite()?

> +{
> +  int byte = -1;

The byte should be defined as an unsigned long.

> +  grub_uint8_t value = 0;
> +  grub_err_t err;
> +
> +  if (argc != 1)
> +    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("one argument expected"));
> +
> +  byte = grub_strtoul (argv[0], NULL, 0);
> +  if (grub_errno)
> +    return grub_errno;
> +
> +  if (byte < 0 || byte >= 0x100)
> +    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid address"));
> +
> +  err = grub_cmos_read (byte, &value);
> +  if (err)
> +    return err;
> +
> +  if (ctxt->state[2].set) {
> +    char buf[sizeof ("XX")];

I would prefer if this is defined at the top of the function.

> +    grub_snprintf (buf, sizeof (buf), "%x", value);
> +    grub_env_set(ctxt->state[2].arg, buf);
> +  } else
> +    grub_printf_("CMOS value at 0x%x is 0x%x\n", byte, value);
> +  return GRUB_ERR_NONE;
> +}
> +
> +static const struct grub_arg_option read_options[] =
> +  {
> +    {0, 'v', 0, N_("Save read value into variable VARNAME."),
> +     N_("VARNAME"), ARG_TYPE_STRING},
> +    {0, 0, 0, 0, 0, 0}
> +  };
> +
> +static grub_command_t cmd, cmd_clean, cmd_set, cmd_write;
> +static grub_extcmd_t cmd_read;
>
>  \f
>  GRUB_MOD_INIT(cmostest)
> @@ -114,6 +181,12 @@ GRUB_MOD_INIT(cmostest)
>  				   N_("BYTE:BIT"),
>  				   /* TRANSLATORS: A bit may be either set (1) or clear (0).  */
>  				   N_("Set bit at BYTE:BIT in CMOS."));
> +  cmd_read = grub_register_extcmd_lockdown ("cmosread", grub_cmd_cmosread, 0,
> +				       N_("[-v VAR] ADDR"),
> +				       N_("Read CMOS byte at ADDR."), read_options);
> +  cmd_write = grub_register_command_lockdown ("cmoswrite", grub_cmd_cmoswrite,
> +					      N_("ADDR VALUE"),
> +					      N_("Set CMOS byte at ADDR to VALUE."));

Please add commands descriptions to the GRUB documentation.

Daniel

_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel

[PATCH] Add commands for reading and writing raw bytes to CMOS

[Vladimir Serbinenko]

With some coreboot configs setting a byte to a magic value
changes behaviour on next boot. Setting bit-by-bit is
possible but not convenient. Add cmosread and cmoswrite for
convenience.

Signed-off-by: Vladimir Serbinenko <phcoder@gmail.com>
---
 grub-core/commands/i386/cmostest.c | 72 +++++++++++++++++++++++++++++-
 1 file changed, 71 insertions(+), 1 deletion(-)

diff --git a/grub-core/commands/i386/cmostest.c b/grub-core/commands/i386/cmostest.c
index 1f0c5341d..814df0f43 100644
--- a/grub-core/commands/i386/cmostest.c
+++ b/grub-core/commands/i386/cmostest.c
@@ -18,9 +18,12 @@
 
 #include <grub/dl.h>
 #include <grub/command.h>
+#include <grub/extcmd.h>
 #include <grub/misc.h>
 #include <grub/cmos.h>
 #include <grub/i18n.h>
+#include <grub/mm.h>
+#include <grub/env.h>
 
 GRUB_MOD_LICENSE ("GPLv3+");
 
@@ -99,7 +102,66 @@ grub_cmd_cmosset (struct grub_command *cmd __attribute__ ((unused)),
   return grub_cmos_write (byte, value | (1 << bit));
 }
 
-static grub_command_t cmd, cmd_clean, cmd_set;
+static grub_err_t
+grub_cmd_cmoswrite (struct grub_command *cmd __attribute__ ((unused)),
+		    int argc, char *argv[])
+{
+  unsigned long byte, value;
+  const char *end;
+
+  if (argc != 2)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("two arguments expected"));
+
+  byte = grub_strtoul (argv[0], &end, 0);
+  if (byte >= 0x100 || argv[0][0] == '\0' || *end != '\0')
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid address"));
+
+  value = grub_strtoul (argv[1], &end, 0);
+  if (value >= 0x100 || argv[1][0] == '\0' || *end != '\0')
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid value"));
+
+  return grub_cmos_write (byte, value);
+}
+
+static grub_err_t
+grub_cmd_cmosread (grub_extcmd_context_t ctxt, int argc, char **argv)
+{
+  unsigned long byte;
+  grub_uint8_t value = 0;
+  grub_err_t err;
+  const char *end;
+
+  if (argc != 1)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("one argument expected"));
+
+  byte = grub_strtoul (argv[0], &end, 0);
+  if (byte >= 0x100 || argv[0][0] == '\0' || *end != '\0')
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid address"));
+
+  err = grub_cmos_read (byte, &value);
+  if (err)
+    return err;
+
+  if (ctxt->state[0].set)
+    {
+      char buf[sizeof ("XX")];
+      grub_snprintf (buf, sizeof (buf), "%x", value);
+      grub_env_set(ctxt->state[0].arg, buf);
+    }
+  else
+    grub_printf_("CMOS value at 0x%lx is 0x%x\n", byte, value);
+  return GRUB_ERR_NONE;
+}
+
+static const struct grub_arg_option read_options[] =
+  {
+    {0, 's', 0, N_("Save read value into variable VARNAME."),
+     N_("VARNAME"), ARG_TYPE_STRING},
+    {0, 0, 0, 0, 0, 0}
+  };
+
+static grub_command_t cmd, cmd_clean, cmd_set, cmd_write;
+static grub_extcmd_t cmd_read;
 
 \f
 GRUB_MOD_INIT(cmostest)
@@ -114,6 +176,12 @@ GRUB_MOD_INIT(cmostest)
 				   N_("BYTE:BIT"),
 				   /* TRANSLATORS: A bit may be either set (1) or clear (0).  */
 				   N_("Set bit at BYTE:BIT in CMOS."));
+  cmd_read = grub_register_extcmd_lockdown ("cmosread", grub_cmd_cmosread, 0,
+				       N_("[-s VAR] ADDR"),
+				       N_("Read CMOS byte at ADDR."), read_options);
+  cmd_write = grub_register_command_lockdown ("cmoswrite", grub_cmd_cmoswrite,
+					      N_("ADDR VALUE"),
+					      N_("Set CMOS byte at ADDR to VALUE."));
 }
 
 GRUB_MOD_FINI(cmostest)
@@ -121,4 +189,6 @@ GRUB_MOD_FINI(cmostest)
   grub_unregister_command (cmd);
   grub_unregister_command (cmd_clean);
   grub_unregister_command (cmd_set);
+  grub_unregister_extcmd (cmd_read);
+  grub_unregister_command (cmd_write);
 }
-- 
2.39.2


_______________________________________________
Grub-devel mailing list
Grub-devel@gnu.org
https://lists.gnu.org/mailman/listinfo/grub-devel