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Subject[tip:x86/trampoline] x86, realmode: header for trampoline code
Commit-ID:  f37240f16bec91f15ce564515f70a6ca9715ce96
Gitweb: http://git.kernel.org/tip/f37240f16bec91f15ce564515f70a6ca9715ce96
Author: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
AuthorDate: Tue, 8 May 2012 21:22:43 +0300
Committer: H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Tue, 8 May 2012 11:48:45 -0700

x86, realmode: header for trampoline code

Added header for trampoline code that can be used to supply
input data to it. This makes interface between real mode code
and kernel cleaner and simpler. Replaced two confusing pointers
to level4 pgt in trampoline_64.S with a single pointer to the
beginning of the page table.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-21-git-send-email-jarkko.sakkinen@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
arch/x86/include/asm/realmode.h | 32 ++++++++++++++++----------
arch/x86/kernel/realmode.c | 27 ++++++++++++----------
arch/x86/kernel/smpboot.c | 2 +-
arch/x86/realmode/rm/header.S | 35 +++++++++++++---------------
arch/x86/realmode/rm/trampoline_32.S | 36 +++++-------------------------
arch/x86/realmode/rm/trampoline_64.S | 18 ++++----------
arch/x86/realmode/rm/trampoline_common.S | 23 +++++++++++++++++++
arch/x86/realmode/rm/wakeup_asm.S | 2 +-
8 files changed, 87 insertions(+), 88 deletions(-)
diff --git a/arch/x86/include/asm/realmode.h b/arch/x86/include/asm/realmode.h
index d3ae49f..1421eed 100644
--- a/arch/x86/include/asm/realmode.h
+++ b/arch/x86/include/asm/realmode.h
@@ -8,25 +8,33 @@
struct real_mode_header {
u32 text_start;
u32 ro_end;
- /* reboot */
-#ifdef CONFIG_X86_32
- u32 machine_real_restart_asm;
-#endif
/* SMP trampoline */
- u32 trampoline_data;
+ u32 trampoline_start;
u32 trampoline_status;
-#ifdef CONFIG_X86_32
- u32 startup_32_smp;
- u32 boot_gdt;
-#else
- u32 startup_64_smp;
- u32 level3_ident_pgt;
- u32 level3_kernel_pgt;
+ u32 trampoline_header;
+#ifdef CONFIG_X86_64
+ u32 trampoline_pgd;
#endif
+ /* ACPI S3 wakeup */
#ifdef CONFIG_ACPI_SLEEP
u32 wakeup_start;
u32 wakeup_header;
#endif
+ /* APM/BIOS reboot */
+#ifdef CONFIG_X86_32
+ u32 machine_real_restart_asm;
+#endif
+} __attribute__((__packed__));
+
+/* This must match data at trampoline_32/64.S */
+struct trampoline_header {
+#ifdef CONFIG_X86_32
+ u32 start;
+ u16 gdt_limit;
+ u32 gdt_base;
+#else
+ u64 start;
+#endif
} __attribute__((__packed__));

extern struct real_mode_header *real_mode_header;
diff --git a/arch/x86/kernel/realmode.c b/arch/x86/kernel/realmode.c
index 632c810..712fba8 100644
--- a/arch/x86/kernel/realmode.c
+++ b/arch/x86/kernel/realmode.c
@@ -17,8 +17,11 @@ void __init setup_real_mode(void)
u16 *seg;
int i;
unsigned char *base;
-
+ struct trampoline_header *trampoline_header;
size_t size = PAGE_ALIGN(real_mode_blob_end - real_mode_blob);
+#ifdef CONFIG_X86_64
+ u64 *trampoline_pgd;
+#endif

/* Has to be in very low memory so we can execute real-mode AP code. */
mem = memblock_find_in_range(0, 1<<20, size, PAGE_SIZE);
@@ -28,7 +31,6 @@ void __init setup_real_mode(void)
base = __va(mem);
memblock_reserve(mem, size);
real_mode_header = (struct real_mode_header *) base;
-
printk(KERN_DEBUG "Base memory trampoline at [%p] %llx size %zu\n",
base, (unsigned long long)mem, size);

@@ -53,18 +55,19 @@ void __init setup_real_mode(void)
*ptr += __pa(base);
}

+ /* Must be perfomed *after* relocation. */
+ trampoline_header = (struct trampoline_header *)
+ __va(real_mode_header->trampoline_header);
+
#ifdef CONFIG_X86_32
- *((u32 *)__va(real_mode_header->startup_32_smp)) = __pa(startup_32_smp);
- *((u32 *)__va(real_mode_header->boot_gdt)) = __pa(boot_gdt);
+ trampoline_header->start = __pa(startup_32_smp);
+ trampoline_header->gdt_limit = __BOOT_DS + 7;
+ trampoline_header->gdt_base = __pa(boot_gdt);
#else
- *((u64 *) __va(real_mode_header->startup_64_smp)) =
- (u64)secondary_startup_64;
-
- *((u64 *) __va(real_mode_header->level3_ident_pgt)) =
- __pa(level3_ident_pgt) + _KERNPG_TABLE;
-
- *((u64 *) __va(real_mode_header->level3_kernel_pgt)) =
- __pa(level3_kernel_pgt) + _KERNPG_TABLE;
+ trampoline_header->start = (u64) secondary_startup_64;
+ trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
+ trampoline_pgd[0] = __pa(level3_ident_pgt) + _KERNPG_TABLE;
+ trampoline_pgd[511] = __pa(level3_kernel_pgt) + _KERNPG_TABLE;
#endif
}

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index b8c0661..757c4b1 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -667,7 +667,7 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu)
volatile u32 *trampoline_status =
(volatile u32 *) __va(real_mode_header->trampoline_status);
/* start_ip had better be page-aligned! */
- unsigned long start_ip = real_mode_header->trampoline_data;
+ unsigned long start_ip = real_mode_header->trampoline_start;

unsigned long boot_error = 0;
int timeout;
diff --git a/arch/x86/realmode/rm/header.S b/arch/x86/realmode/rm/header.S
index c83005c..b4c3263 100644
--- a/arch/x86/realmode/rm/header.S
+++ b/arch/x86/realmode/rm/header.S
@@ -7,28 +7,25 @@
#include <linux/linkage.h>
#include <asm/page_types.h>

- .section ".header", "a"
+ .section ".header", "a"

GLOBAL(real_mode_header)
- .long pa_text_start
- .long pa_ro_end
-#ifdef CONFIG_X86_32
- .long pa_machine_real_restart_asm
-#endif
- /* SMP trampoline */
- .long pa_trampoline_data
- .long pa_trampoline_status
-#ifdef CONFIG_X86_32
- .long pa_startup_32_smp
- .long pa_boot_gdt
-#else
- .long pa_startup_64_smp
- .long pa_level3_ident_pgt
- .long pa_level3_kernel_pgt
+ .long pa_text_start
+ .long pa_ro_end
+ /* SMP trampoline */
+ .long pa_trampoline_start
+ .long pa_trampoline_status
+ .long pa_trampoline_header
+#ifdef CONFIG_X86_64
+ .long pa_trampoline_pgd;
#endif
- /* ACPI sleep */
+ /* ACPI S3 wakeup */
#ifdef CONFIG_ACPI_SLEEP
- .long pa_wakeup_start
- .long pa_wakeup_header
+ .long pa_wakeup_start
+ .long pa_wakeup_header
+#endif
+ /* APM/BIOS reboot */
+#ifdef CONFIG_X86_32
+ .long pa_machine_real_restart_asm
#endif
END(real_mode_header)
diff --git a/arch/x86/realmode/rm/trampoline_32.S b/arch/x86/realmode/rm/trampoline_32.S
index 1ecdbb5..6fc064b 100644
--- a/arch/x86/realmode/rm/trampoline_32.S
+++ b/arch/x86/realmode/rm/trampoline_32.S
@@ -13,16 +13,10 @@
*
* We jump into arch/x86/kernel/head_32.S.
*
- * On entry to trampoline_data, the processor is in real mode
+ * On entry to trampoline_start, the processor is in real mode
* with 16-bit addressing and 16-bit data. CS has some value
* and IP is zero. Thus, we load CS to the physical segment
* of the real mode code before doing anything further.
- *
- * The structure real_mode_header includes entries that need
- * to be set up before executing this code:
- *
- * startup_32_smp
- * boot_gdt
*/

#include <linux/linkage.h>
@@ -35,7 +29,7 @@
.code16

.balign PAGE_SIZE
-ENTRY(trampoline_data)
+ENTRY(trampoline_start)
wbinvd # Needed for NUMA-Q should be harmless for others

LJMPW_RM(1f)
@@ -45,7 +39,7 @@ ENTRY(trampoline_data)

cli # We should be safe anyway

- movl startup_32_smp, %eax # where we need to go
+ movl tr_start, %eax # where we need to go

movl $0xA5A5A5A5, trampoline_status
# write marker for master knows we're running
@@ -56,8 +50,8 @@ ENTRY(trampoline_data)
* operand size is 16bit. Use lgdtl instead to force operand size
* to 32 bit.
*/
- lidtl boot_idt_descr # load idt with 0, 0
- lgdtl boot_gdt_descr # load gdt with whatever is appropriate
+ lidtl tr_idt # load idt with 0, 0
+ lgdtl tr_gdt # load gdt with whatever is appropriate

movw $1, %dx # protected mode (PE) bit
lmsw %dx # into protected mode
@@ -69,22 +63,4 @@ ENTRY(trampoline_data)
ENTRY(startup_32) # note: also used from wakeup_asm.S
jmp *%eax

- .section ".rodata","a"
-
- .balign 4
-boot_idt_descr:
- .word 0 # idt limit = 0
- .long 0 # idt base = 0L
-
- .data
-
-boot_gdt_descr:
- .word __BOOT_DS + 7 # gdt limit
-GLOBAL(boot_gdt)
- .long 0 # gdt base
-
- .bss
-
- .balign 4
-GLOBAL(trampoline_status) .space 4
-GLOBAL(startup_32_smp) .space 4
+#include "trampoline_common.S"
diff --git a/arch/x86/realmode/rm/trampoline_64.S b/arch/x86/realmode/rm/trampoline_64.S
index f71ea08..3f72932 100644
--- a/arch/x86/realmode/rm/trampoline_64.S
+++ b/arch/x86/realmode/rm/trampoline_64.S
@@ -10,7 +10,7 @@
* trampoline page to make our stack and everything else
* is a mystery.
*
- * On entry to trampoline_data, the processor is in real mode
+ * On entry to trampoline_start, the processor is in real mode
* with 16-bit addressing and 16-bit data. CS has some value
* and IP is zero. Thus, data addresses need to be absolute
* (no relocation) and are taken with regard to r_base.
@@ -37,7 +37,7 @@
.balign PAGE_SIZE
.code16

-ENTRY(trampoline_data)
+ENTRY(trampoline_start)
cli # We should be safe anyway
wbinvd

@@ -97,7 +97,7 @@ ENTRY(startup_32)
movl %eax, %cr4 # Enable PAE mode

# Setup trampoline 4 level pagetables
- movl $pa_level3_ident_pgt, %eax
+ movl $pa_trampoline_pgd, %eax
movl %eax, %cr3

movl $MSR_EFER, %ecx
@@ -122,7 +122,7 @@ ENTRY(startup_32)
.balign 4
ENTRY(startup_64)
# Now jump into the kernel using virtual addresses
- jmpq *startup_64_smp(%rip)
+ jmpq *tr_start(%rip)

.section ".rodata","a"
.balign 16
@@ -143,12 +143,4 @@ tgdt:
.quad 0x00cf93000000ffff # __KERNEL_DS
tgdt_end:

- .bss
-
- .balign PAGE_SIZE
-GLOBAL(level3_ident_pgt) .space 511*8
-GLOBAL(level3_kernel_pgt) .space 8
-
- .balign 8
-GLOBAL(startup_64_smp) .space 8
-GLOBAL(trampoline_status) .space 4
+#include "trampoline_common.S"
diff --git a/arch/x86/realmode/rm/trampoline_common.S b/arch/x86/realmode/rm/trampoline_common.S
new file mode 100644
index 0000000..c3f951c
--- /dev/null
+++ b/arch/x86/realmode/rm/trampoline_common.S
@@ -0,0 +1,23 @@
+ .section ".rodata","a"
+
+ .balign 4
+tr_idt: .fill 1, 6, 0
+
+ .bss
+
+ .balign 4
+GLOBAL(trampoline_status) .space 4
+
+GLOBAL(trampoline_header)
+#ifdef CONFIG_X86_32
+ tr_start: .space 4
+ tr_gdt: .space 6
+#else
+ tr_start: .space 8
+#endif
+END(trampoline_header)
+
+#ifdef CONFIG_X86_64
+ .balign PAGE_SIZE
+GLOBAL(trampoline_pgd) .space PAGE_SIZE
+#endif
diff --git a/arch/x86/realmode/rm/wakeup_asm.S b/arch/x86/realmode/rm/wakeup_asm.S
index 8a57c5a..46108f0 100644
--- a/arch/x86/realmode/rm/wakeup_asm.S
+++ b/arch/x86/realmode/rm/wakeup_asm.S
@@ -132,7 +132,7 @@ ENTRY(wakeup_start)
ljmpl $__KERNEL_CS, $pa_startup_32
/* -> jmp *%eax in trampoline_32.S */
#else
- jmp trampoline_data
+ jmp trampoline_start
#endif

bogus_real_magic:

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