From: Ross Philipson <ross.philipson@oracle.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org,
linux-integrity@vger.kernel.org, linux-doc@vger.kernel.org,
linux-crypto@vger.kernel.org, kexec@lists.infradead.org,
linux-efi@vger.kernel.org
Cc: ross.philipson@oracle.com, dpsmith@apertussolutions.com,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
hpa@zytor.com, dave.hansen@linux.intel.com, ardb@kernel.org,
mjg59@srcf.ucam.org, James.Bottomley@hansenpartnership.com,
peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca,
luto@amacapital.net, nivedita@alum.mit.edu,
herbert@gondor.apana.org.au, davem@davemloft.net,
kanth.ghatraju@oracle.com, trenchboot-devel@googlegroups.com
Subject: [PATCH v8 01/15] x86/boot: Place kernel_info at a fixed offset
Date: Wed, 14 Feb 2024 14:18:33 -0800 [thread overview]
Message-ID: <20240214221847.2066632-2-ross.philipson@oracle.com> (raw)
In-Reply-To: <20240214221847.2066632-1-ross.philipson@oracle.com>
From: Arvind Sankar <nivedita@alum.mit.edu>
There are use cases for storing the offset of a symbol in kernel_info.
For example, the trenchboot series [0] needs to store the offset of the
Measured Launch Environment header in kernel_info.
Since commit (note: commit ID from tip/master)
commit 527afc212231 ("x86/boot: Check that there are no run-time relocations")
run-time relocations are not allowed in the compressed kernel, so simply
using the symbol in kernel_info, as
.long symbol
will cause a linker error because this is not position-independent.
With kernel_info being a separate object file and in a different section
from startup_32, there is no way to calculate the offset of a symbol
from the start of the image in a position-independent way.
To enable such use cases, put kernel_info into its own section which is
placed at a predetermined offset (KERNEL_INFO_OFFSET) via the linker
script. This will allow calculating the symbol offset in a
position-independent way, by adding the offset from the start of
kernel_info to KERNEL_INFO_OFFSET.
Ensure that kernel_info is aligned, and use the SYM_DATA.* macros
instead of bare labels. This stores the size of the kernel_info
structure in the ELF symbol table.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Ross Philipson <ross.philipson@oracle.com>
Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
---
arch/x86/boot/compressed/kernel_info.S | 19 +++++++++++++++----
arch/x86/boot/compressed/kernel_info.h | 12 ++++++++++++
arch/x86/boot/compressed/vmlinux.lds.S | 6 ++++++
3 files changed, 33 insertions(+), 4 deletions(-)
create mode 100644 arch/x86/boot/compressed/kernel_info.h
diff --git a/arch/x86/boot/compressed/kernel_info.S b/arch/x86/boot/compressed/kernel_info.S
index f818ee8fba38..c18f07181dd5 100644
--- a/arch/x86/boot/compressed/kernel_info.S
+++ b/arch/x86/boot/compressed/kernel_info.S
@@ -1,12 +1,23 @@
/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/linkage.h>
#include <asm/bootparam.h>
+#include "kernel_info.h"
- .section ".rodata.kernel_info", "a"
+/*
+ * If a field needs to hold the offset of a symbol from the start
+ * of the image, use the macro below, eg
+ * .long rva(symbol)
+ * This will avoid creating run-time relocations, which are not
+ * allowed in the compressed kernel.
+ */
+
+#define rva(X) (((X) - kernel_info) + KERNEL_INFO_OFFSET)
- .global kernel_info
+ .section ".rodata.kernel_info", "a"
-kernel_info:
+ .balign 16
+SYM_DATA_START(kernel_info)
/* Header, Linux top (structure). */
.ascii "LToP"
/* Size. */
@@ -19,4 +30,4 @@ kernel_info:
kernel_info_var_len_data:
/* Empty for time being... */
-kernel_info_end:
+SYM_DATA_END_LABEL(kernel_info, SYM_L_LOCAL, kernel_info_end)
diff --git a/arch/x86/boot/compressed/kernel_info.h b/arch/x86/boot/compressed/kernel_info.h
new file mode 100644
index 000000000000..c127f84aec63
--- /dev/null
+++ b/arch/x86/boot/compressed/kernel_info.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef BOOT_COMPRESSED_KERNEL_INFO_H
+#define BOOT_COMPRESSED_KERNEL_INFO_H
+
+#ifdef CONFIG_X86_64
+#define KERNEL_INFO_OFFSET 0x500
+#else /* 32-bit */
+#define KERNEL_INFO_OFFSET 0x100
+#endif
+
+#endif /* BOOT_COMPRESSED_KERNEL_INFO_H */
diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
index 083ec6d7722a..718c52f3f1e6 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -7,6 +7,7 @@ OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT)
#include <asm/cache.h>
#include <asm/page_types.h>
+#include "kernel_info.h"
#ifdef CONFIG_X86_64
OUTPUT_ARCH(i386:x86-64)
@@ -27,6 +28,11 @@ SECTIONS
HEAD_TEXT
_ehead = . ;
}
+ .rodata.kernel_info KERNEL_INFO_OFFSET : {
+ *(.rodata.kernel_info)
+ }
+ ASSERT(ABSOLUTE(kernel_info) == KERNEL_INFO_OFFSET, "kernel_info at bad address!")
+
.rodata..compressed : {
*(.rodata..compressed)
}
--
2.39.3
next prev parent reply other threads:[~2024-02-14 22:32 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-14 22:18 [PATCH v8 00/15] x86: Trenchboot secure dynamic launch Linux kernel support Ross Philipson
2024-02-14 22:18 ` Ross Philipson [this message]
2024-02-15 7:56 ` [PATCH v8 01/15] x86/boot: Place kernel_info at a fixed offset Ard Biesheuvel
2024-02-15 10:56 ` Daniel Kiper
2024-03-21 13:45 ` Daniel P. Smith
2024-03-22 14:18 ` H. Peter Anvin
2024-03-23 1:33 ` Daniel P. Smith
2024-02-14 22:18 ` [PATCH v8 02/15] Documentation/x86: Secure Launch kernel documentation Ross Philipson
2024-02-14 22:18 ` [PATCH v8 03/15] x86: Secure Launch Kconfig Ross Philipson
2024-02-15 7:59 ` Ard Biesheuvel
2024-02-15 22:20 ` ross.philipson
2024-02-14 22:18 ` [PATCH v8 04/15] x86: Secure Launch Resource Table header file Ross Philipson
2024-02-15 8:08 ` Ard Biesheuvel
2024-02-22 2:03 ` Andrew Cooper
2024-02-22 2:10 ` ross.philipson
2024-02-22 17:49 ` ross.philipson
2024-03-29 22:38 ` Kim Phillips
2024-03-29 22:38 ` Kim Phillips
2024-03-29 22:38 ` Kim Phillips
2024-04-01 18:25 ` ross.philipson
2024-02-14 22:18 ` [PATCH v8 05/15] x86: Secure Launch main " Ross Philipson
2024-02-14 22:18 ` [PATCH v8 06/15] x86: Add early SHA support for Secure Launch early measurements Ross Philipson
2024-02-15 8:17 ` Ard Biesheuvel
2024-02-22 3:04 ` Andrew Cooper
2024-02-22 9:34 ` Ard Biesheuvel
2024-02-22 12:30 ` Andrew Cooper
2024-02-23 9:27 ` Ard Biesheuvel
2024-02-23 16:42 ` Andrew Cooper
2024-02-23 17:54 ` Eric Biggers
2024-02-23 18:20 ` Andrew Cooper
2024-02-23 18:30 ` Eric Biggers
2024-04-03 16:32 ` Andy Lutomirski
2024-04-03 23:56 ` Eric Biggers
2024-04-04 4:55 ` ross.philipson
2024-04-04 14:55 ` Jarkko Sakkinen
2024-02-14 22:18 ` [PATCH v8 07/15] x86: Secure Launch kernel early boot stub Ross Philipson
2024-02-15 8:29 ` Ard Biesheuvel
2024-02-15 22:26 ` ross.philipson
2024-02-14 22:18 ` [PATCH v8 08/15] x86: Secure Launch kernel late " Ross Philipson
2024-02-14 22:18 ` [PATCH v8 09/15] x86: Secure Launch SMP bringup support Ross Philipson
2024-02-14 22:18 ` [PATCH v8 10/15] kexec: Secure Launch kexec SEXIT support Ross Philipson
2024-02-14 22:18 ` [PATCH v8 11/15] reboot: Secure Launch SEXIT support on reboot paths Ross Philipson
2024-02-14 22:18 ` [PATCH v8 12/15] tpm: Add ability to set the preferred locality the TPM chip uses Ross Philipson
2024-02-14 22:18 ` [PATCH v8 13/15] tpm: Add sysfs interface to allow setting and querying the preferred locality Ross Philipson
2024-02-14 22:18 ` [PATCH v8 14/15] x86: Secure Launch late initcall platform module Ross Philipson
2024-02-15 8:40 ` Ard Biesheuvel
2024-02-22 13:57 ` Daniel P. Smith
2024-02-23 9:36 ` Ard Biesheuvel
2024-03-21 14:11 ` Daniel P. Smith
2024-02-16 1:53 ` kernel test robot
2024-02-17 7:53 ` kernel test robot
2024-02-14 22:18 ` [PATCH v8 15/15] x86: EFI stub DRTM launch support for Secure Launch Ross Philipson
2024-02-15 9:01 ` Ard Biesheuvel
2024-02-21 20:17 ` ross.philipson
2024-02-21 20:37 ` H. Peter Anvin
2024-02-21 23:24 ` Ard Biesheuvel
2024-02-17 7:31 ` kernel test robot
2024-02-17 20:06 ` kernel test robot
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