Mailing List Archive

[xen staging] x86/boot: Fix data placement around __high_start()
commit ffa5d037c78fe175f31373deec0759ff8cc8d66c
Author: Andrew Cooper <andrew.cooper3@citrix.com>
AuthorDate: Mon Nov 29 19:52:05 2021 +0000
Commit: Andrew Cooper <andrew.cooper3@citrix.com>
CommitDate: Thu Dec 2 20:02:55 2021 +0000

x86/boot: Fix data placement around __high_start()

multiboot_ptr should be in __initdata - it is only used on the BSP path.
Furthermore, the .align 8 then .long means that stack_start is misaligned.

Move both into setup.c, which lets the compiler handle the details correctly,
as well as providing proper debug information for them.

Declare stack_start in setup.h and avoid extern-ing it locally in smpboot.c.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
xen/arch/x86/boot/x86_64.S | 8 --------
xen/arch/x86/setup.c | 6 ++++++
xen/arch/x86/smpboot.c | 3 +--
xen/include/asm-x86/setup.h | 2 ++
4 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/xen/arch/x86/boot/x86_64.S b/xen/arch/x86/boot/x86_64.S
index d61048c583..27f52e7a77 100644
--- a/xen/arch/x86/boot/x86_64.S
+++ b/xen/arch/x86/boot/x86_64.S
@@ -67,14 +67,6 @@ ENTRY(__high_start)
call __start_xen
BUG /* __start_xen() shouldn't return. */

- .data
- .align 8
-multiboot_ptr:
- .long 0
-
-GLOBAL(stack_start)
- .quad cpu0_stack + STACK_SIZE - CPUINFO_sizeof
-
.section .data.page_aligned, "aw", @progbits
.align PAGE_SIZE, 0
/*
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index 495b4b7d51..6613e56a21 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -141,6 +141,12 @@ unsigned long __read_mostly xen_virt_end;
char __section(".bss.stack_aligned") __aligned(STACK_SIZE)
cpu0_stack[STACK_SIZE];

+/* Used by the BSP/AP paths to find the higher half stack mapping to use. */
+void *stack_start = cpu0_stack + STACK_SIZE - sizeof(struct cpu_info);
+
+/* Used by the boot asm to stash the relocated multiboot info pointer. */
+unsigned int __initdata multiboot_ptr;
+
struct cpuinfo_x86 __read_mostly boot_cpu_data = { 0, 0, 0, 0, -1 };

unsigned long __read_mostly mmu_cr4_features = XEN_MINIMAL_CR4;
diff --git a/xen/arch/x86/smpboot.c b/xen/arch/x86/smpboot.c
index 329cfdb6c9..08c0f2d9df 100644
--- a/xen/arch/x86/smpboot.c
+++ b/xen/arch/x86/smpboot.c
@@ -42,6 +42,7 @@
#include <asm/microcode.h>
#include <asm/msr.h>
#include <asm/mtrr.h>
+#include <asm/setup.h>
#include <asm/spec_ctrl.h>
#include <asm/time.h>
#include <asm/tboot.h>
@@ -419,8 +420,6 @@ void start_secondary(void *unused)
startup_cpu_idle_loop();
}

-extern void *stack_start;
-
static int wakeup_secondary_cpu(int phys_apicid, unsigned long start_eip)
{
unsigned long send_status = 0, accept_status = 0;
diff --git a/xen/include/asm-x86/setup.h b/xen/include/asm-x86/setup.h
index 24be46115d..eb9d7b433c 100644
--- a/xen/include/asm-x86/setup.h
+++ b/xen/include/asm-x86/setup.h
@@ -12,6 +12,8 @@ extern char __2M_rwdata_start[], __2M_rwdata_end[];
extern unsigned long xenheap_initial_phys_start;
extern uint64_t boot_tsc_stamp;

+extern void *stack_start;
+
void early_cpu_init(void);
void early_time_init(void);

--
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