diff options
Diffstat (limited to 'arch/x86/entry/entry_64_fred.S')
| -rw-r--r-- | arch/x86/entry/entry_64_fred.S | 42 |
1 files changed, 31 insertions, 11 deletions
diff --git a/arch/x86/entry/entry_64_fred.S b/arch/x86/entry/entry_64_fred.S index a02bc6f3d2e6..894f7f16eb80 100644 --- a/arch/x86/entry/entry_64_fred.S +++ b/arch/x86/entry/entry_64_fred.S @@ -4,6 +4,7 @@ */ #include <linux/export.h> +#include <linux/kvm_types.h> #include <asm/asm.h> #include <asm/fred.h> @@ -16,7 +17,7 @@ .macro FRED_ENTER UNWIND_HINT_END_OF_STACK - ENDBR + ANNOTATE_NOENDBR PUSH_AND_CLEAR_REGS movq %rsp, %rdi /* %rdi -> pt_regs */ .endm @@ -58,6 +59,7 @@ SYM_CODE_END(asm_fred_entrypoint_kernel) #if IS_ENABLED(CONFIG_KVM_INTEL) SYM_FUNC_START(asm_fred_entry_from_kvm) + ANNOTATE_NOENDBR push %rbp mov %rsp, %rbp @@ -96,8 +98,7 @@ SYM_FUNC_START(asm_fred_entry_from_kvm) push %rdi /* fred_ss handed in by the caller */ push %rbp pushf - mov $__KERNEL_CS, %rax - push %rax + push $__KERNEL_CS /* * Unlike the IDT event delivery, FRED _always_ pushes an error code @@ -111,21 +112,40 @@ SYM_FUNC_START(asm_fred_entry_from_kvm) push %rax /* Return RIP */ push $0 /* Error code, 0 for IRQ/NMI */ - PUSH_AND_CLEAR_REGS clear_bp=0 unwind_hint=0 + PUSH_AND_CLEAR_REGS clear_callee=0 unwind_hint=0 + movq %rsp, %rdi /* %rdi -> pt_regs */ + /* + * At this point: {rdi, rsi, rdx, rcx, r8, r9}, {r10, r11}, {rax, rdx} + * are clobbered, which corresponds to: arguments, extra caller-saved + * and return. All registers a C function is allowed to clobber. + * + * Notably, the callee-saved registers: {rbx, r12, r13, r14, r15} + * are untouched, with the exception of rbp, which carries the stack + * frame and will be restored before exit. + * + * Further calling another C function will not alter this state. + */ call __fred_entry_from_kvm /* Call the C entry point */ - POP_REGS - ERETS -1: + /* - * Objtool doesn't understand what ERETS does, this hint tells it that - * yes, we'll reach here and with what stack state. A save/restore pair - * isn't strictly needed, but it's the simplest form. + * When FRED, use ERETS to potentially clear NMIs, otherwise simply + * restore the stack pointer. + */ + ALTERNATIVE "nop; nop; mov %rbp, %rsp", \ + __stringify(add $C_PTREGS_SIZE, %rsp; ERETS), \ + X86_FEATURE_FRED + +1: /* + * Objtool doesn't understand ERETS, and the cfi register state is + * different from initial_func_cfi due to PUSH_REGS. Tell it the state + * is similar to where UNWIND_HINT_SAVE is. */ UNWIND_HINT_RESTORE + pop %rbp RET SYM_FUNC_END(asm_fred_entry_from_kvm) -EXPORT_SYMBOL_GPL(asm_fred_entry_from_kvm); +EXPORT_SYMBOL_FOR_KVM(asm_fred_entry_from_kvm); #endif |