linux-kernel - [PATCH v2 1/2] x86, kexec_file_load: Don't setup EFI info if EFI runtime is not enabled

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Date:   Tue, 15 Jan 2019 17:58:33 +0800
From:   Kairui Song <kasong@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        x86@...nel.org, dyoung@...hat.com, bhe@...hat.com,
        kexec@...ts.infradead.org, akpm@...ux-foundation.org,
        robert.moore@...el.com, erik.schmauss@...el.com,
        rafael.j.wysocki@...el.com, lenb@...nel.org,
        Kairui Song <kasong@...hat.com>
Subject: [PATCH v2 1/2] x86, kexec_file_load: Don't setup EFI info if EFI runtime is not enabled

Currently with "efi=noruntime" in kernel command line, calling
kexec_file_load will raise below problem:

[   97.967067] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[   97.967894] #PF error: [normal kernel read fault]
...
[   97.980456] Call Trace:
[   97.980724]  efi_runtime_map_copy+0x28/0x30
[   97.981267]  bzImage64_load+0x688/0x872
[   97.981794]  arch_kexec_kernel_image_load+0x6d/0x70
[   97.982441]  kimage_file_alloc_init+0x13e/0x220
[   97.983035]  __x64_sys_kexec_file_load+0x144/0x290
[   97.983586]  do_syscall_64+0x55/0x1a0
[   97.983962]  entry_SYSCALL_64_after_hwframe+0x44/0xa9

When efi runtime is not enabled, efi memmap is not mapped, so just skip
EFI info setup.

Suggested-by: Dave Young <dyoung@...hat.com>
Signed-off-by: Kairui Song <kasong@...hat.com>
---
 arch/x86/kernel/kexec-bzimage64.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 0d5efa34f359..53917a3ebf94 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -167,6 +167,9 @@ setup_efi_state(struct boot_params *params, unsigned long params_load_addr,
 	struct efi_info *current_ei = &boot_params.efi_info;
 	struct efi_info *ei = &params->efi_info;
 
+	if (!efi_enabled(EFI_RUNTIME_SERVICES))
+		return 0;
+
 	if (!current_ei->efi_memmap_size)
 		return 0;
 
-- 
2.20.1