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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2017-12-04 15:40:56 +0300
committerThomas Gleixner <tglx@linutronix.de>2017-12-07 10:36:26 +0100
commit6d7e0ba2d2be9e50cccba213baf07e0e183c1b24 (patch)
tree7fd60dce0164cd66d4f68bc2b2158ab336f7e6b7 /arch/x86/boot
parent08529078d8d9adf689bf39cc38d53979a0869970 (diff)
x86/boot/compressed/64: Print error if 5-level paging is not supported
If the machine does not support the paging mode for which the kernel was compiled, the boot process cannot continue. It's not possible to let the kernel detect the mismatch as it does not even reach the point where cpu features can be evaluted due to a triple fault in the KASLR setup. Instead of instantaneous silent reboot, emit an error message which gives the user the information why the boot fails. Fixes: 77ef56e4f0fb ("x86: Enable 5-level paging support via CONFIG_X86_5LEVEL=y") Reported-by: Borislav Petkov <bp@suse.de> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Borislav Petkov <bp@suse.de> Cc: Andi Kleen <ak@linux.intel.com> Cc: stable@vger.kernel.org Cc: Andy Lutomirski <luto@amacapital.net> Cc: linux-mm@kvack.org Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lkml.kernel.org/r/20171204124059.63515-3-kirill.shutemov@linux.intel.com
Diffstat (limited to 'arch/x86/boot')
-rw-r--r--arch/x86/boot/compressed/misc.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
index b50c42455e25..98761a1576ce 100644
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -169,6 +169,16 @@ void __puthex(unsigned long value)
}
}
+static bool l5_supported(void)
+{
+ /* Check if leaf 7 is supported. */
+ if (native_cpuid_eax(0) < 7)
+ return 0;
+
+ /* Check if la57 is supported. */
+ return native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31));
+}
+
#if CONFIG_X86_NEED_RELOCS
static void handle_relocations(void *output, unsigned long output_len,
unsigned long virt_addr)
@@ -362,6 +372,12 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
console_init();
debug_putstr("early console in extract_kernel\n");
+ if (IS_ENABLED(CONFIG_X86_5LEVEL) && !l5_supported()) {
+ error("This linux kernel as configured requires 5-level paging\n"
+ "This CPU does not support the required 'cr4.la57' feature\n"
+ "Unable to boot - please use a kernel appropriate for your CPU\n");
+ }
+
free_mem_ptr = heap; /* Heap */
free_mem_end_ptr = heap + BOOT_HEAP_SIZE;