Adding Robbie...
Please CC him next time when you post these patches. I would want to
hear his opinion too. Or at least he is aware what is happening here...
On Thu, Dec 15, 2022 at 11:29:31PM -0600, Glenn Washburn wrote:
> If the macro PRINT_GDB_SYM_LOAD_CMD is non-zero, compile code which will
> print the command needed to load symbols for the GRUB EFI kernel. This is
> needed because EFI firmware determines where to load the GRUB EFI at
> runtime, and so the relevant addresses are not known ahead of time.
>
> The command is a custom command defined in the gdb_grub GDB script. So
> GDB should be started with the script as an argument to the -x option or
> sourced into an active GDB session before running the outputted command.
I think this functionality should be disabled when lockdown is enforced,
e.g. on UEFI platforms with Secure Boot enabled.
> Co-developed-by: Peter Jones <pjo...@redhat.com>
> Signed-off-by: Glenn Washburn <developm...@efficientek.com>
> ---
> config.h.in | 3 +++
> grub-core/kern/efi/efi.c | 4 ++--
> grub-core/kern/efi/init.c | 19 ++++++++++++++++++-
> include/grub/efi/efi.h | 2 +-
> 4 files changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/config.h.in b/config.h.in
> index 4d1e50eba7..c31eee1bca 100644
> --- a/config.h.in
> +++ b/config.h.in
> @@ -13,6 +13,9 @@
> #define MM_DEBUG @MM_DEBUG@
> #endif
>
> +/* Define to 1 to enable printing of gdb command to load module symbols. */
> +#define PRINT_GDB_SYM_LOAD_CMD 0
> +
> /* Define to 1 to enable disk cache statistics. */
> #define DISK_CACHE_STATS @DISK_CACHE_STATS@
> #define BOOT_TIME_STATS @BOOT_TIME_STATS@
> diff --git a/grub-core/kern/efi/efi.c b/grub-core/kern/efi/efi.c
> index cf49d6357e..17bd06f7e6 100644
> --- a/grub-core/kern/efi/efi.c
> +++ b/grub-core/kern/efi/efi.c
> @@ -299,7 +299,7 @@ grub_efi_get_variable (const char *var, const
> grub_efi_guid_t *guid,
> /* Search the mods section from the PE32/PE32+ image. This code uses
> a PE32 header, but should work with PE32+ as well. */
> grub_addr_t
> -grub_efi_modules_addr (void)
> +grub_efi_section_addr (const char *section_name)
> {
> grub_efi_loaded_image_t *image;
> struct grub_msdos_image_header *header;
> @@ -328,7 +328,7 @@ grub_efi_modules_addr (void)
> i < coff_header->num_sections;
> i++, section++)
> {
> - if (grub_strcmp (section->name, "mods") == 0)
> + if (grub_strcmp (section->name, section_name) == 0)
> break;
> }
>
> diff --git a/grub-core/kern/efi/init.c b/grub-core/kern/efi/init.c
> index b67bc73a1b..ed3d463c8f 100644
> --- a/grub-core/kern/efi/init.c
> +++ b/grub-core/kern/efi/init.c
> @@ -101,10 +101,24 @@ stack_protector_init (void)
>
> grub_addr_t grub_modbase;
>
> +#if PRINT_GDB_SYM_LOAD_CMD
> +static void
> +grub_efi_print_gdb_info (void)
> +{
> + grub_addr_t text;
> +
> + text = grub_efi_section_addr (".text");
> + if (!text)
> + return;
> +
> + grub_printf ("dynamic_load_symbols %p\n", (void *)text);
> +}
> +#endif
> +
> void
> grub_efi_init (void)
> {
> - grub_modbase = grub_efi_modules_addr ();
> + grub_modbase = grub_efi_section_addr ("mods");
> /* First of all, initialize the console so that GRUB can display
> messages. */
> grub_console_init ();
> @@ -127,6 +141,9 @@ grub_efi_init (void)
> efi_call_4 (grub_efi_system_table->boot_services->set_watchdog_timer,
> 0, 0, 0, NULL);
>
> +#if PRINT_GDB_SYM_LOAD_CMD
> + grub_efi_print_gdb_info ();
> +#endif
> grub_efidisk_init ();
> }
>
> diff --git a/include/grub/efi/efi.h b/include/grub/efi/efi.h
> index e61272de53..586ac856b5 100644
> --- a/include/grub/efi/efi.h
> +++ b/include/grub/efi/efi.h
> @@ -109,7 +109,7 @@ grub_err_t grub_arch_efi_linux_boot_image(grub_addr_t
> addr, grub_size_t size,
> char *args);
> #endif
>
> -grub_addr_t grub_efi_modules_addr (void);
> +grub_addr_t grub_efi_section_addr (const char *section);
>
> void grub_efi_mm_init (void);
> void grub_efi_mm_fini (void);
Daniel
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