[added,to,the,3.18,stable,tree] x86/efi: Store upper bits of command line buffer address in ext_cmd_line_ptr

Message ID 1434946411-9021-58-git-send-email-sasha.levin@oracle.com
State New
Headers show

Commit Message

Sasha Levin June 22, 2015, 4:13 a.m.
From: Roy Franz <roy.franz@linaro.org>

This patch has been added to the 3.18 stable tree. If you have any
objections, please let us know.

Patch

===============

[ Upstream commit 98b228f55014870092c15d7d168fecac69f2f12a ]

Until now, the EFI stub was only setting the 32 bit cmd_line_ptr in
the setup_header structure, so on 64 bit platforms this could be truncated.
This patch adds setting the upper bits of the buffer address in
ext_cmd_line_ptr.  This case was likely never hit, as the allocation
for this buffer is done at the lowest available address.  Only
x86_64 kernels have this problem, as the 1-1 mapping mandated
by EFI ensures that all memory is 32 bit addressable on 32 bit
platforms.  The EFI stub does not support mixed mode, so the
32 bit kernel on 64 bit firmware case does not need to be handled.

Signed-off-by: Roy Franz <roy.franz@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
 arch/x86/boot/compressed/eboot.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
index 1acf605..3790a66 100644
--- a/arch/x86/boot/compressed/eboot.c
+++ b/arch/x86/boot/compressed/eboot.c
@@ -1110,6 +1110,8 @@  struct boot_params *make_boot_params(struct efi_config *c)
 	if (!cmdline_ptr)
 		goto fail;
 	hdr->cmd_line_ptr = (unsigned long)cmdline_ptr;
+	/* Fill in upper bits of command line address, NOP on 32 bit  */
+	boot_params->ext_cmd_line_ptr = (u64)(unsigned long)cmdline_ptr >> 32;
 
 	hdr->ramdisk_image = 0;
 	hdr->ramdisk_size = 0;