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Subject[tip:x86/mm] x86/boot/compressed/64: Set up trampoline memory
Commit-ID:  32fcefa2bfc8961987e91d1daeb00624b4176d2e
Gitweb: https://git.kernel.org/tip/32fcefa2bfc8961987e91d1daeb00624b4176d2e
Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
AuthorDate: Mon, 26 Feb 2018 21:04:50 +0300
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 12 Mar 2018 09:37:25 +0100

x86/boot/compressed/64: Set up trampoline memory

This patch clears up trampoline memory and copies trampoline code in
place. It's not yet used though.

Tested-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20180226180451.86788-5-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/boot/compressed/head_64.S | 3 ++-
arch/x86/boot/compressed/pgtable.h | 9 +++++++++
arch/x86/boot/compressed/pgtable_64.c | 7 +++++++
3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 8ba0582c65d5..c813cb004056 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -501,8 +501,9 @@ relocated:
jmp *%rax

.code32
+ENTRY(trampoline_32bit_src)
compatible_mode:
- /* Setup data and stack segments */
+ /* Set up data and stack segments */
movl $__KERNEL_DS, %eax
movl %eax, %ds
movl %eax, %ss
diff --git a/arch/x86/boot/compressed/pgtable.h b/arch/x86/boot/compressed/pgtable.h
index 57722a2fe2a0..91f75638f6e6 100644
--- a/arch/x86/boot/compressed/pgtable.h
+++ b/arch/x86/boot/compressed/pgtable.h
@@ -3,9 +3,18 @@

#define TRAMPOLINE_32BIT_SIZE (2 * PAGE_SIZE)

+#define TRAMPOLINE_32BIT_PGTABLE_OFFSET 0
+
+#define TRAMPOLINE_32BIT_CODE_OFFSET PAGE_SIZE
+#define TRAMPOLINE_32BIT_CODE_SIZE 0x60
+
+#define TRAMPOLINE_32BIT_STACK_END TRAMPOLINE_32BIT_SIZE
+
#ifndef __ASSEMBLER__

extern unsigned long *trampoline_32bit;

+extern void trampoline_32bit_src(void *return_ptr);
+
#endif /* __ASSEMBLER__ */
#endif /* BOOT_COMPRESSED_PAGETABLE_H */
diff --git a/arch/x86/boot/compressed/pgtable_64.c b/arch/x86/boot/compressed/pgtable_64.c
index 01d08d3e3e43..810c2c32d98e 100644
--- a/arch/x86/boot/compressed/pgtable_64.c
+++ b/arch/x86/boot/compressed/pgtable_64.c
@@ -76,6 +76,13 @@ struct paging_config paging_prepare(void)
/* Preserve trampoline memory */
memcpy(trampoline_save, trampoline_32bit, TRAMPOLINE_32BIT_SIZE);

+ /* Clear trampoline memory first */
+ memset(trampoline_32bit, 0, TRAMPOLINE_32BIT_SIZE);
+
+ /* Copy trampoline code in place */
+ memcpy(trampoline_32bit + TRAMPOLINE_32BIT_CODE_OFFSET / sizeof(unsigned long),
+ &trampoline_32bit_src, TRAMPOLINE_32BIT_CODE_SIZE);
+
return paging_config;
}

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