diff options
| -rw-r--r-- | arch/x86/include/asm/bitops.h | 7 | ||||
| -rw-r--r-- | arch/x86/include/asm/kexec.h | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/machine_kexec_64.c | 21 | ||||
| -rw-r--r-- | arch/x86/kernel/relocate_kernel_64.S | 186 |
4 files changed, 214 insertions, 5 deletions
diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h index 100413aff640..eebbc8889e70 100644 --- a/arch/x86/include/asm/bitops.h +++ b/arch/x86/include/asm/bitops.h @@ -248,7 +248,7 @@ arch_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr) static __always_inline unsigned long variable__ffs(unsigned long word) { - asm("rep; bsf %1,%0" + asm("tzcnt %1,%0" : "=r" (word) : ASM_INPUT_RM (word)); return word; @@ -267,10 +267,7 @@ static __always_inline unsigned long variable__ffs(unsigned long word) static __always_inline unsigned long variable_ffz(unsigned long word) { - asm("rep; bsf %1,%0" - : "=r" (word) - : "r" (~word)); - return word; + return variable__ffs(~word); } /** diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h index 5432457d2338..fb4537c58b54 100644 --- a/arch/x86/include/asm/kexec.h +++ b/arch/x86/include/asm/kexec.h @@ -8,6 +8,9 @@ # define PA_PGD 2 # define PA_SWAP_PAGE 3 # define PAGES_NR 4 +#else +/* Size of each exception handler referenced by the IDT */ +# define KEXEC_DEBUG_EXC_HANDLER_SIZE 6 /* PUSHI, PUSHI, 2-byte JMP */ #endif # define KEXEC_CONTROL_PAGE_SIZE 4096 @@ -59,6 +62,8 @@ struct kimage; extern unsigned long kexec_va_control_page; extern unsigned long kexec_pa_table_page; extern unsigned long kexec_pa_swap_page; +extern gate_desc kexec_debug_idt[]; +extern unsigned char kexec_debug_exc_vectors[]; #endif /* diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index a68f5a0a9f37..cc73f9708464 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -304,6 +304,24 @@ static void load_segments(void) ); } +static void prepare_debug_idt(unsigned long control_page, unsigned long vec_ofs) +{ + gate_desc idtentry = { 0 }; + int i; + + idtentry.bits.p = 1; + idtentry.bits.type = GATE_TRAP; + idtentry.segment = __KERNEL_CS; + idtentry.offset_low = (control_page & 0xFFFF) + vec_ofs; + idtentry.offset_middle = (control_page >> 16) & 0xFFFF; + idtentry.offset_high = control_page >> 32; + + for (i = 0; i < 16; i++) { + kexec_debug_idt[i] = idtentry; + idtentry.offset_low += KEXEC_DEBUG_EXC_HANDLER_SIZE; + } +} + int machine_kexec_prepare(struct kimage *image) { void *control_page = page_address(image->control_code_page); @@ -321,6 +339,9 @@ int machine_kexec_prepare(struct kimage *image) if (image->type == KEXEC_TYPE_DEFAULT) kexec_pa_swap_page = page_to_pfn(image->swap_page) << PAGE_SHIFT; + prepare_debug_idt((unsigned long)__pa(control_page), + (unsigned long)kexec_debug_exc_vectors - reloc_start); + __memcpy(control_page, __relocate_kernel_start, reloc_end - reloc_start); set_memory_rox((unsigned long)control_page, 1); diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S index ac058971a382..29cb399a34d4 100644 --- a/arch/x86/kernel/relocate_kernel_64.S +++ b/arch/x86/kernel/relocate_kernel_64.S @@ -50,6 +50,11 @@ SYM_DATA_START_LOCAL(kexec_debug_gdt) .quad 0x00cf92000000ffff /* __KERNEL_DS */ SYM_DATA_END_LABEL(kexec_debug_gdt, SYM_L_LOCAL, kexec_debug_gdt_end) + .balign 8 +SYM_DATA_START(kexec_debug_idt) + .skip 0x100, 0x00 +SYM_DATA_END(kexec_debug_idt) + .section .text..relocate_kernel,"ax"; .code64 SYM_CODE_START_NOALIGN(relocate_kernel) @@ -139,6 +144,15 @@ SYM_CODE_START_LOCAL_NOALIGN(identity_mapped) movq %ds, %rax movq %rax, %ds + /* Now an IDTR on the stack to load the IDT the kernel created */ + leaq kexec_debug_idt(%rip), %rsi + pushq %rsi + pushw $0xff + lidt (%rsp) + addq $10, %rsp + + //int3 + /* * Clear X86_CR4_CET (if it was set) such that we can clear CR0_WP * below. @@ -364,3 +378,175 @@ SYM_CODE_START_LOCAL_NOALIGN(swap_pages) ret int3 SYM_CODE_END(swap_pages) + +/* + * Generic 'print character' routine (as yet unimplemented) + * - %al: Character to be printed (may clobber %rax) + * - %rdx: MMIO address or port. + */ +SYM_CODE_START_LOCAL_NOALIGN(pr_char) + UNWIND_HINT_FUNC + ANNOTATE_NOENDBR + ANNOTATE_UNRET_SAFE + ret +SYM_CODE_END(pr_char) + +/* + * Load pr_char function pointer into %rsi and load %rdx with whatever + * that function wants to see there (typically port/MMIO address). + */ +.macro pr_setup + /* No output; pr_char just returns */ + leaq pr_char(%rip), %rsi +.endm + +/* Print the nybble in %bl, clobber %rax */ +SYM_CODE_START_LOCAL_NOALIGN(pr_nybble) + UNWIND_HINT_FUNC + movb %bl, %al + nop + andb $0x0f, %al + addb $0x30, %al + cmpb $0x3a, %al + jb 1f + addb $('a' - '0' - 10), %al + ANNOTATE_RETPOLINE_SAFE +1: jmp *%rsi +SYM_CODE_END(pr_nybble) + +SYM_CODE_START_LOCAL_NOALIGN(pr_qword) + UNWIND_HINT_FUNC + movq $16, %rcx +1: rolq $4, %rbx + call pr_nybble + loop 1b + movb $'\n', %al + ANNOTATE_RETPOLINE_SAFE + jmp *%rsi +SYM_CODE_END(pr_qword) + +.macro print_reg a, b, c, d, r + movb $\a, %al + ANNOTATE_RETPOLINE_SAFE + call *%rsi + movb $\b, %al + ANNOTATE_RETPOLINE_SAFE + call *%rsi + movb $\c, %al + ANNOTATE_RETPOLINE_SAFE + call *%rsi + movb $\d, %al + ANNOTATE_RETPOLINE_SAFE + call *%rsi + movq \r, %rbx + call pr_qword +.endm + +SYM_CODE_START_NOALIGN(kexec_debug_exc_vectors) + /* Each of these is 6 bytes. */ +.macro vec_err exc + UNWIND_HINT_ENTRY + . = kexec_debug_exc_vectors + (\exc * KEXEC_DEBUG_EXC_HANDLER_SIZE) + nop + nop + pushq $\exc + jmp exc_handler +.endm + +.macro vec_noerr exc + UNWIND_HINT_ENTRY + . = kexec_debug_exc_vectors + (\exc * KEXEC_DEBUG_EXC_HANDLER_SIZE) + pushq $0 + pushq $\exc + jmp exc_handler +.endm + + ANNOTATE_NOENDBR + vec_noerr 0 // #DE + vec_noerr 1 // #DB + vec_noerr 2 // #NMI + vec_noerr 3 // #BP + vec_noerr 4 // #OF + vec_noerr 5 // #BR + vec_noerr 6 // #UD + vec_noerr 7 // #NM + vec_err 8 // #DF + vec_noerr 9 + vec_err 10 // #TS + vec_err 11 // #NP + vec_err 12 // #SS + vec_err 13 // #GP + vec_err 14 // #PF + vec_noerr 15 +SYM_CODE_END(kexec_debug_exc_vectors) + +SYM_CODE_START_LOCAL_NOALIGN(exc_handler) + /* No need for RET mitigations during kexec */ + VALIDATE_UNRET_END + + pushq %rax + pushq %rbx + pushq %rcx + pushq %rdx + pushq %rsi + + /* Stack frame */ +#define EXC_SS 0x58 /* Architectural... */ +#define EXC_RSP 0x50 +#define EXC_EFLAGS 0x48 +#define EXC_CS 0x40 +#define EXC_RIP 0x38 +#define EXC_ERRORCODE 0x30 /* Either architectural or zero pushed by handler */ +#define EXC_EXCEPTION 0x28 /* Pushed by handler entry point */ +#define EXC_RAX 0x20 /* Pushed just above in exc_handler */ +#define EXC_RBX 0x18 +#define EXC_RCX 0x10 +#define EXC_RDX 0x08 +#define EXC_RSI 0x00 + + /* Set up %rdx/%rsi for debug output */ + pr_setup + + /* rip and exception info */ + print_reg 'E', 'x', 'c', ':', EXC_EXCEPTION(%rsp) + print_reg 'E', 'r', 'r', ':', EXC_ERRORCODE(%rsp) + print_reg 'r', 'i', 'p', ':', EXC_RIP(%rsp) + print_reg 'r', 's', 'p', ':', EXC_RSP(%rsp) + + /* We spilled these to the stack */ + print_reg 'r', 'a', 'x', ':', EXC_RAX(%rsp) + print_reg 'r', 'b', 'x', ':', EXC_RBX(%rsp) + print_reg 'r', 'c', 'x', ':', EXC_RCX(%rsp) + print_reg 'r', 'd', 'x', ':', EXC_RDX(%rsp) + print_reg 'r', 's', 'i', ':', EXC_RSI(%rsp) + + /* Other registers untouched */ + print_reg 'r', 'd', 'i', ':', %rdi + print_reg 'r', '8', ' ', ':', %r8 + print_reg 'r', '9', ' ', ':', %r9 + print_reg 'r', '1', '0', ':', %r10 + print_reg 'r', '1', '1', ':', %r11 + print_reg 'r', '1', '2', ':', %r12 + print_reg 'r', '1', '3', ':', %r13 + print_reg 'r', '1', '4', ':', %r14 + print_reg 'r', '1', '5', ':', %r15 + print_reg 'c', 'r', '2', ':', %cr2 + + /* Only return from INT3 */ + cmpq $3, EXC_EXCEPTION(%rsp) + jne .Ldie + + popq %rsi + popq %rdx + popq %rcx + popq %rbx + popq %rax + + addq $16, %rsp + iretq + +.Ldie: + hlt + jmp .Ldie + +SYM_CODE_END(exc_handler) |