[tip:x86/urgent] x86/boot: Clear RSDP address in boot_params for broken loaders

[tip-bot for Juergen Gross]

Commit-ID:  182ddd16194cd082f25fa1b063dae3c7c5cce384
Gitweb:     https://git.kernel.org/tip/182ddd16194cd082f25fa1b063dae3c7c5cce384
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Mon, 3 Dec 2018 11:38:11 +0100
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 3 Dec 2018 11:56:37 +0100

x86/boot: Clear RSDP address in boot_params for broken loaders

Gunnar Krueger reported a systemd-boot failure and bisected it down to:

  e6e094e053af75 ("x86/acpi, x86/boot: Take RSDP address from boot params if available")

In case a broken boot loader doesn't clear its 'struct boot_params', clear
rsdp_addr in sanitize_boot_params().

Reported-by: Gunnar Krueger <taijian@xxxxxxxxx>
Tested-by: Gunnar Krueger <taijian@xxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: bp@xxxxxxxxx
Cc: sstabellini@xxxxxxxxxx
Fixes: e6e094e053af75 ("x86/acpi, x86/boot: Take RSDP address from boot params if available")
Link: http://lkml.kernel.org/r/20181203103811.17056-1-jgross@xxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 arch/x86/include/asm/bootparam_utils.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/bootparam_utils.h b/arch/x86/include/asm/bootparam_utils.h
index a07ffd23e4dd..f6f6ef436599 100644
--- a/arch/x86/include/asm/bootparam_utils.h
+++ b/arch/x86/include/asm/bootparam_utils.h
@@ -36,6 +36,7 @@ static void sanitize_boot_params(struct boot_params *boot_params)
 	 */
 	if (boot_params->sentinel) {
 		/* fields in boot_params are left uninitialized, clear them */
+		boot_params->acpi_rsdp_addr = 0;
 		memset(&boot_params->ext_ramdisk_image, 0,
 		       (char *)&boot_params->efi_info -
 			(char *)&boot_params->ext_ramdisk_image);