Split load_gdt_tss() functionality into:
1. Load gdt/tss.
2. Setup segments in 64-bit mode.
3. Update cs segment via far-return.
and move load_gdt_tss() to desc.c to share this code between
EFI and non-EFI tests.
Signed-off-by: Varad Gautam <varad.gautam@xxxxxxxx>
---
lib/x86/desc.c | 6 ++++++
lib/x86/desc.h | 1 +
lib/x86/setup.c | 9 ++++++++-
x86/efi/efistart64.S | 22 +++++++++++++---------
4 files changed, 28 insertions(+), 10 deletions(-)
diff --git a/lib/x86/desc.c b/lib/x86/desc.c
index 713ad0b..d627a22 100644
--- a/lib/x86/desc.c
+++ b/lib/x86/desc.c
@@ -370,6 +370,12 @@ void set_gdt_entry(int sel, unsigned long base, u32 limit, u8 type, u8 flags)
#endif
}
+void load_gdt_tss(size_t tss_offset)
+{
+ lgdt(&gdt_descr);
+ ltr(tss_offset);
+}
+
#ifndef __x86_64__
void set_gdt_task_gate(u16 sel, u16 tss_sel)
{
diff --git a/lib/x86/desc.h b/lib/x86/desc.h
index 5eb21e4..30a0c90 100644
--- a/lib/x86/desc.h
+++ b/lib/x86/desc.h
@@ -222,6 +222,7 @@ void set_idt_entry(int vec, void *addr, int dpl);
void set_idt_sel(int vec, u16 sel);
void set_idt_dpl(int vec, u16 dpl);
void set_gdt_entry(int sel, unsigned long base, u32 limit, u8 access, u8 gran);
+void load_gdt_tss(size_t tss_offset);
void set_intr_alt_stack(int e, void *fn);
void print_current_tss_info(void);
handler handle_exception(u8 v, handler fn);
diff --git a/lib/x86/setup.c b/lib/x86/setup.c
index 3f3b1e2..e5a690a 100644
--- a/lib/x86/setup.c
+++ b/lib/x86/setup.c
@@ -170,7 +170,9 @@ void setup_multiboot(struct mbi_bootinfo *bi)
#ifdef CONFIG_EFI
/* From x86/efi/efistart64.S */
-extern void load_gdt_tss(size_t tss_offset);
+extern void update_cs(void);
+extern void setup_segments64(u64 gs_base);
+extern u8 stacktop;
static efi_status_t setup_memory_allocator(efi_bootinfo_t *efi_bootinfo)
{
@@ -271,10 +273,15 @@ static void setup_page_table(void)
static void setup_gdt_tss(void)
{
size_t tss_offset;
+ u64 gs_base;
/* 64-bit setup_tss does not use the stacktop argument. */
tss_offset = setup_tss(NULL);
load_gdt_tss(tss_offset);
+
+ update_cs();
+ gs_base = (u64)(&stacktop) - (PAGE_SIZE * (apic_id() + 1));
+ setup_segments64(gs_base);
}
efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo)
diff --git a/x86/efi/efistart64.S b/x86/efi/efistart64.S
index 7e924dc..c8fd3a2 100644
--- a/x86/efi/efistart64.S
+++ b/x86/efi/efistart64.S
@@ -37,15 +37,8 @@ ptl4:
.code64
.text
-.globl load_gdt_tss
-load_gdt_tss:
- /* Load GDT */
- lgdt gdt_descr(%rip)
-
- /* Load TSS */
- mov %rdi, %rax
- ltr %ax
-
+.globl setup_segments64
+setup_segments64:
/* Update data segments */
mov $0x10, %ax /* 3rd entry in gdt64: 32/64-bit data segment */
mov %ax, %ds
@@ -54,6 +47,17 @@ load_gdt_tss:
mov %ax, %gs
mov %ax, %ss
+ /* Setup percpu base */
+ MSR_GS_BASE = 0xc0000101
+ mov %rdi, %rax
+ mov $0, %edx
+ mov $MSR_GS_BASE, %ecx
+ wrmsr
+
+ ret
+
+.globl update_cs
+update_cs:
/*
* Update the code segment by putting it on the stack before the return
* address, then doing a far return: this will use the new code segment
--
2.32.0
