1 files changed, 151 insertions, 0 deletions
diff --git a/arch/x86/entry/vdso/vsgx.S b/arch/x86/entry/vdso/vsgx.S
new file mode 100644
index 000000000..d77d278ee
--- /dev/null
+++ b/arch/x86/entry/vdso/vsgx.S
@@ -0,0 +1,151 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <linux/linkage.h>
+#include <asm/export.h>
+#include <asm/errno.h>
+#include <asm/enclu.h>
+
+#include "extable.h"
+
+/* Relative to %rbp. */
+#define SGX_ENCLAVE_OFFSET_OF_RUN		16
+
+/* The offsets relative to struct sgx_enclave_run. */
+#define SGX_ENCLAVE_RUN_TCS			0
+#define SGX_ENCLAVE_RUN_LEAF			8
+#define SGX_ENCLAVE_RUN_EXCEPTION_VECTOR	12
+#define SGX_ENCLAVE_RUN_EXCEPTION_ERROR_CODE	14
+#define SGX_ENCLAVE_RUN_EXCEPTION_ADDR		16
+#define SGX_ENCLAVE_RUN_USER_HANDLER		24
+#define SGX_ENCLAVE_RUN_USER_DATA		32	/* not used */
+#define SGX_ENCLAVE_RUN_RESERVED_START		40
+#define SGX_ENCLAVE_RUN_RESERVED_END		256
+
+.code64
+.section .text, "ax"
+
+SYM_FUNC_START(__vdso_sgx_enter_enclave)
+	/* Prolog */
+	.cfi_startproc
+	push	%rbp
+	.cfi_adjust_cfa_offset	8
+	.cfi_rel_offset		%rbp, 0
+	mov	%rsp, %rbp
+	.cfi_def_cfa_register	%rbp
+	push	%rbx
+	.cfi_rel_offset		%rbx, -8
+
+	mov	%ecx, %eax
+.Lenter_enclave:
+	/* EENTER <= function <= ERESUME */
+	cmp	$EENTER, %eax
+	jb	.Linvalid_input
+	cmp	$ERESUME, %eax
+	ja	.Linvalid_input
+
+	mov	SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rcx
+
+	/* Validate that the reserved area contains only zeros. */
+	mov	$SGX_ENCLAVE_RUN_RESERVED_START, %rbx
+1:
+	cmpq	$0, (%rcx, %rbx)
+	jne	.Linvalid_input
+	add	$8, %rbx
+	cmpq	$SGX_ENCLAVE_RUN_RESERVED_END, %rbx
+	jne	1b
+
+	/* Load TCS and AEP */
+	mov	SGX_ENCLAVE_RUN_TCS(%rcx), %rbx
+	lea	.Lasync_exit_pointer(%rip), %rcx
+
+	/* Single ENCLU serving as both EENTER and AEP (ERESUME) */
+.Lasync_exit_pointer:
+.Lenclu_eenter_eresume:
+	enclu
+
+	/* EEXIT jumps here unless the enclave is doing something fancy. */
+	mov	SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx
+
+	/* Set exit_reason. */
+	movl	$EEXIT, SGX_ENCLAVE_RUN_LEAF(%rbx)
+
+	/* Invoke userspace's exit handler if one was provided. */
+.Lhandle_exit:
+	cmpq	$0, SGX_ENCLAVE_RUN_USER_HANDLER(%rbx)
+	jne	.Linvoke_userspace_handler
+
+	/* Success, in the sense that ENCLU was attempted. */
+	xor	%eax, %eax
+
+.Lout:
+	pop	%rbx
+	leave
+	.cfi_def_cfa		%rsp, 8
+	RET
+
+	/* The out-of-line code runs with the pre-leave stack frame. */
+	.cfi_def_cfa		%rbp, 16
+
+.Linvalid_input:
+	mov	$(-EINVAL), %eax
+	jmp	.Lout
+
+.Lhandle_exception:
+	mov	SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx
+
+	/* Set the exception info. */
+	mov	%eax, (SGX_ENCLAVE_RUN_LEAF)(%rbx)
+	mov	%di,  (SGX_ENCLAVE_RUN_EXCEPTION_VECTOR)(%rbx)
+	mov	%si,  (SGX_ENCLAVE_RUN_EXCEPTION_ERROR_CODE)(%rbx)
+	mov	%rdx, (SGX_ENCLAVE_RUN_EXCEPTION_ADDR)(%rbx)
+	jmp	.Lhandle_exit
+
+.Linvoke_userspace_handler:
+	/* Pass the untrusted RSP (at exit) to the callback via %rcx. */
+	mov	%rsp, %rcx
+
+	/* Save struct sgx_enclave_exception %rbx is about to be clobbered. */
+	mov	%rbx, %rax
+
+	/* Save the untrusted RSP offset in %rbx (non-volatile register). */
+	mov	%rsp, %rbx
+	and	$0xf, %rbx
+
+	/*
+	 * Align stack per x86_64 ABI. Note, %rsp needs to be 16-byte aligned
+	 * _after_ pushing the parameters on the stack, hence the bonus push.
+	 */
+	and	$-0x10, %rsp
+	push	%rax
+
+	/* Push struct sgx_enclave_exception as a param to the callback. */
+	push	%rax
+
+	/* Clear RFLAGS.DF per x86_64 ABI */
+	cld
+
+	/*
+	 * Load the callback pointer to %rax and lfence for LVI (load value
+	 * injection) protection before making the call.
+	 */
+	mov	SGX_ENCLAVE_RUN_USER_HANDLER(%rax), %rax
+	lfence
+	call	*%rax
+
+	/* Undo the post-exit %rsp adjustment. */
+	lea	0x10(%rsp, %rbx), %rsp
+
+	/*
+	 * If the return from callback is zero or negative, return immediately,
+	 * else re-execute ENCLU with the positive return value interpreted as
+	 * the requested ENCLU function.
+	 */
+	cmp	$0, %eax
+	jle	.Lout
+	jmp	.Lenter_enclave
+
+	.cfi_endproc
+
+_ASM_VDSO_EXTABLE_HANDLE(.Lenclu_eenter_eresume, .Lhandle_exception)
+
+SYM_FUNC_END(__vdso_sgx_enter_enclave)