x86/fred: Fix init_task thread stack pointer initialization

As TOP_OF_KERNEL_STACK_PADDING was defined as 0 on x86_64, it went
unnoticed that the initialization of the .sp field in INIT_THREAD and some
calculations in the low level startup code do not take the padding into
account.

FRED enabled kernels require a 16 byte padding, which means that the init
task initialization and the low level startup code use the wrong stack
offset.

Subtract TOP_OF_KERNEL_STACK_PADDING in all affected places to adjust for
this.

Fixes: 65c9cc9e2c14 ("x86/fred: Reserve space for the FRED stack frame")
Fixes: 3adee777ad0d ("x86/smpboot: Remove initial_stack on 64-bit")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Closes: https://lore.kernel.org/oe-lkp/202402262159.183c2a37-lkp@intel.com
Link: https://lore.kernel.org/r/20240304083333.449322-1-xin@zytor.com

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 26620d7642a9fcf9d4a822140a1dd009399ee16a..17fe81998ce48175c1b2208b010be46784f02d25 100644 (file)
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -664,8 +664,10 @@ static __always_inline void prefetchw(const void *x)
 #else
 extern unsigned long __end_init_task[];
 
-#define INIT_THREAD {                                                      \
-       .sp     = (unsigned long)&__end_init_task - sizeof(struct pt_regs), \
+#define INIT_THREAD {                                                  \
+       .sp     = (unsigned long)&__end_init_task -                     \
+                 TOP_OF_KERNEL_STACK_PADDING -                         \
+                 sizeof(struct pt_regs),                               \
 }
 
 extern unsigned long KSTK_ESP(struct task_struct *task);

diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index d4918d03efb4b7765bff35d3e5f28a8c3a2bc99d..c38e43589046b9b180e03c99848f8503db7a37e3 100644 (file)
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -26,6 +26,7 @@
 #include <asm/apicdef.h>
 #include <asm/fixmap.h>
 #include <asm/smp.h>
+#include <asm/thread_info.h>
 
 /*
  * We are not able to switch in one step to the final KERNEL ADDRESS SPACE
@@ -66,7 +67,7 @@ SYM_CODE_START_NOALIGN(startup_64)
        mov     %rsi, %r15
 
        /* Set up the stack for verify_cpu() */
-       leaq    (__end_init_task - PTREGS_SIZE)(%rip), %rsp
+       leaq    (__end_init_task - TOP_OF_KERNEL_STACK_PADDING - PTREGS_SIZE)(%rip), %rsp
 
        leaq    _text(%rip), %rdi
 

diff --git a/arch/x86/xen/xen-head.S b/arch/x86/xen/xen-head.S
index a0ea285878dbe168ce5bf8cea61d5c642c4d0b72..04101b984f24dab88bb020add4afe4774628e627 100644 (file)
--- a/arch/x86/xen/xen-head.S
+++ b/arch/x86/xen/xen-head.S
@@ -49,7 +49,7 @@ SYM_CODE_START(startup_xen)
        ANNOTATE_NOENDBR
        cld
 
-       leaq    (__end_init_task - PTREGS_SIZE)(%rip), %rsp
+       leaq    (__end_init_task - TOP_OF_KERNEL_STACK_PADDING - PTREGS_SIZE)(%rip), %rsp
 
        /* Set up %gs.
         *