From c603a309cc75f3dd018ddb20ee44c05047918cbf Mon Sep 17 00:00:00 2001
From: Thomas Lendacky <Thomas.Lendacky@amd.com>
Date: Wed, 19 Jun 2019 18:40:57 +0000
Subject: x86/mm: Identify the end of the kernel area to be reserved
The memory occupied by the kernel is reserved using memblock_reserve()
in setup_arch(). Currently, the area is from symbols _text to __bss_stop.
Everything after __bss_stop must be specifically reserved otherwise it
is discarded. This is not clearly documented.
Add a new symbol, __end_of_kernel_reserve, that more readily identifies
what is reserved, along with comments that indicate what is reserved,
what is discarded and what needs to be done to prevent a section from
being discarded.
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Tested-by: Lianbo Jiang <lijiang@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Pavel Tatashin <pasha.tatashin@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <rrichter@marvell.com>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Sinan Kaya <okaya@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "x86@kernel.org" <x86@kernel.org>
Link: https://lkml.kernel.org/r/7db7da45b435f8477f25e66f292631ff766a844c.1560969363.git.thomas.lendacky@amd.com
---
arch/x86/kernel/vmlinux.lds.S | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
(limited to 'arch/x86/kernel/vmlinux.lds.S')
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 0850b5149345..ca2252ca6ad7 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -368,6 +368,14 @@ SECTIONS
__bss_stop = .;
}
+ /*
+ * The memory occupied from _text to here, __end_of_kernel_reserve, is
+ * automatically reserved in setup_arch(). Anything after here must be
+ * explicitly reserved using memblock_reserve() or it will be discarded
+ * and treated as available memory.
+ */
+ __end_of_kernel_reserve = .;
+
. = ALIGN(PAGE_SIZE);
.brk : AT(ADDR(.brk) - LOAD_OFFSET) {
__brk_base = .;
@@ -382,7 +390,6 @@ SECTIONS
STABS_DEBUG
DWARF_DEBUG
- /* Sections to be discarded */
DISCARDS
/DISCARD/ : {
*(.eh_frame)
--
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