[PATCH 4/5] x86/boot/compressed/64: Set up trampoline memory

Kirill A. Shutemov
2018-02-26T18:05:05Z

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

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
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;
}

--
2.16.1