Commit 7b99819d authored by Joerg Roedel's avatar Joerg Roedel Committed by Borislav Petkov

x86/head/64: Load segment registers earlier

Make sure segments are properly set up before setting up an IDT and
doing anything that might cause a #VC exception. This is later needed
for early exception handling.
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200907131613.12703-32-joro@8bytes.org
parent e04b8833
......@@ -166,6 +166,32 @@ SYM_CODE_START(secondary_startup_64)
*/
lgdt early_gdt_descr(%rip)
/* set up data segments */
xorl %eax,%eax
movl %eax,%ds
movl %eax,%ss
movl %eax,%es
/*
* We don't really need to load %fs or %gs, but load them anyway
* to kill any stale realmode selectors. This allows execution
* under VT hardware.
*/
movl %eax,%fs
movl %eax,%gs
/* Set up %gs.
*
* The base of %gs always points to fixed_percpu_data. If the
* stack protector canary is enabled, it is located at %gs:40.
* Note that, on SMP, the boot cpu uses init data section until
* the per cpu areas are set up.
*/
movl $MSR_GS_BASE,%ecx
movl initial_gs(%rip),%eax
movl initial_gs+4(%rip),%edx
wrmsr
/* Check if nx is implemented */
movl $0x80000001, %eax
cpuid
......@@ -193,32 +219,6 @@ SYM_CODE_START(secondary_startup_64)
pushq $0
popfq
/* set up data segments */
xorl %eax,%eax
movl %eax,%ds
movl %eax,%ss
movl %eax,%es
/*
* We don't really need to load %fs or %gs, but load them anyway
* to kill any stale realmode selectors. This allows execution
* under VT hardware.
*/
movl %eax,%fs
movl %eax,%gs
/* Set up %gs.
*
* The base of %gs always points to fixed_percpu_data. If the
* stack protector canary is enabled, it is located at %gs:40.
* Note that, on SMP, the boot cpu uses init data section until
* the per cpu areas are set up.
*/
movl $MSR_GS_BASE,%ecx
movl initial_gs(%rip),%eax
movl initial_gs+4(%rip),%edx
wrmsr
/* rsi is pointer to real mode structure with interesting info.
pass it to C */
movq %rsi, %rdi
......
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