From: Borislav Petkov Date: Wed, 14 Jun 2017 14:06:25 +0000 (+0200) Subject: x86/microcode: Look for the initrd at the correct address on 32-bit X-Git-Tag: v4.13~455^2~2 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=a3d98c9358e3be28282ff60dcca01dbc9f402f30;p=mirror_ubuntu-artful-kernel.git x86/microcode: Look for the initrd at the correct address on 32-bit Early during boot, the BSP finds the ramdisk's position from boot_params but by the time the APs get to boot, the BSP has continued in the mean time and has potentially managed to relocate that ramdisk. And in that case, the APs need to find the ramdisk at its new position, in *physical* memory as they're running before paging has been enabled. Thus, get the updated physical location of the ramdisk which is in the relocated_ramdisk variable. Signed-off-by: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170614140626.4462-1-bp@alien8.de Signed-off-by: Ingo Molnar --- diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c index e53d3c909840..9cb98ee103db 100644 --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -290,6 +290,17 @@ struct cpio_data find_microcode_in_initrd(const char *path, bool use_pa) return (struct cpio_data){ NULL, 0, "" }; if (initrd_start) start = initrd_start; + } else { + /* + * The picture with physical addresses is a bit different: we + * need to get the *physical* address to which the ramdisk was + * relocated, i.e., relocated_ramdisk (not initrd_start) and + * since we're running from physical addresses, we need to access + * relocated_ramdisk through its *physical* address too. + */ + u64 *rr = (u64 *)__pa_nodebug(&relocated_ramdisk); + if (*rr) + start = *rr; } return find_cpio_data(path, (void *)start, size, NULL);