Reaching 64-bit mode requires setting up a valid stack and percpu regions for each CPU and configuring a page table before far-jumping to the 64-bit entrypoint. This functionality is already present as prepare_64() and ap_start32() routines in start32.S for non-EFI test builds. However since EFI builds (-fPIC) cannot use absolute addressing, and 32-bit mode does not allow RIP-relative addressing, these routines need some changes. Modify prepare_64() and ap_start32() asm routines to calculate label addresses during runtime on CONFIG_EFI. To ease the common case, replace the far-jump to ap_start64() with a far-return. This brings the APs into 64-bit mode to loop at a known location. Signed-off-by: Varad Gautam <varad.gautam@xxxxxxxx> --- lib/x86/setup.c | 2 +- lib/x86/smp.c | 3 +++ x86/efi/efistart64.S | 13 ++++++++++--- x86/start32.S | 46 +++++++++++++++++++++++++++++++++++++++++--- 4 files changed, 57 insertions(+), 7 deletions(-) diff --git a/lib/x86/setup.c b/lib/x86/setup.c index 5d32d3f..e2f7967 100644 --- a/lib/x86/setup.c +++ b/lib/x86/setup.c @@ -326,11 +326,11 @@ efi_status_t setup_efi(efi_bootinfo_t *efi_bootinfo) setup_idt(); load_idt(); mask_pic_interrupts(); + setup_page_table(); enable_apic(); ap_init(); enable_x2apic(); smp_init(); - setup_page_table(); return EFI_SUCCESS; } diff --git a/lib/x86/smp.c b/lib/x86/smp.c index 5cc1648..cee82ac 100644 --- a/lib/x86/smp.c +++ b/lib/x86/smp.c @@ -148,6 +148,8 @@ void smp_reset_apic(void) #ifdef CONFIG_EFI extern u8 gdt32_descr, gdt32, gdt32_end; extern u8 ap_start32; +extern u32 smp_stacktop; +extern u8 stacktop; #endif void ap_init(void) @@ -168,6 +170,7 @@ void ap_init(void) idt_entry_t *gate_descr; u16 *gdt32_descr_reladdr = (u16 *) (PAGE_SIZE - sizeof(u16)); + smp_stacktop = ((u64) (&stacktop)) - 4096; /* * gdt32_descr for CONFIG_EFI needs to be filled here dynamically * since compile time calculation of offsets is not allowed when diff --git a/x86/efi/efistart64.S b/x86/efi/efistart64.S index 00279b8..149e3f7 100644 --- a/x86/efi/efistart64.S +++ b/x86/efi/efistart64.S @@ -14,6 +14,9 @@ max_cpus = MAX_TEST_CPUS .globl stacktop stacktop: +.globl smp_stacktop +smp_stacktop: .long 0 + .align PAGE_SIZE .globl ptl2 ptl2: @@ -93,6 +96,10 @@ gdt32_descr: sipi_end: .code32 -.globl ap_start32 -ap_start32: - jmp ap_start32 + +#include "../start32.S" + +.code64: + +ap_start64: + jmp ap_start64 diff --git a/x86/start32.S b/x86/start32.S index 9e00474..2089be7 100644 --- a/x86/start32.S +++ b/x86/start32.S @@ -27,7 +27,16 @@ MSR_GS_BASE = 0xc0000101 .endm prepare_64: - lgdt gdt_descr +#ifdef CONFIG_EFI + call prepare_64_1 +prepare_64_1: + pop %edx + add $gdt_descr - prepare_64_1, %edx +#else + mov $gdt_descr, %edx +#endif + lgdtl (%edx) + setup_segments xor %eax, %eax @@ -38,7 +47,14 @@ enter_long_mode: bts $5, %eax // pae mov %eax, %cr4 +#ifdef CONFIG_EFI + call prepare_64_2 +prepare_64_2: + pop %eax + add $ptl4 - prepare_64_2, %eax +#else mov pt_root, %eax +#endif mov %eax, %cr3 efer = 0xc0000080 @@ -53,10 +69,34 @@ efer = 0xc0000080 mov %eax, %cr0 ret +.globl ap_start32 ap_start32: setup_segments + +#ifdef CONFIG_EFI + call ap_start32_1 +ap_start32_1: + pop %edx + add $smp_stacktop - ap_start32_1, %edx +#else + mov $smp_stacktop, %edx +#endif mov $-4096, %esp - lock xaddl %esp, smp_stacktop + lock xaddl %esp, (%edx) + setup_percpu_area call prepare_64 - ljmpl $8, $ap_start64 + +#ifdef CONFIG_EFI + call ap_start32_2 +ap_start32_2: + pop %edx + add $ap_start64 - ap_start32_2, %edx +#else + mov $ap_start64, %edx +#endif + + pushl $0x08 + pushl %edx + + lretl -- 2.35.1
