[PATCH for_v23 v2 2/3] x86/vdso: sgx: Use an extra push to align the stack

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Use a "PUSH reg" instead of "SUB imm32, reg" to align the stack.  The
PUSH is a one-byte opcode, whereas the SUB is a four-byte opcode.

Suggested-by: Cedric Xing <cedric.xing@xxxxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
 arch/x86/entry/vdso/vsgx_enter_enclave.S | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/vdso/vsgx_enter_enclave.S b/arch/x86/entry/vdso/vsgx_enter_enclave.S
index e56737cc9f2c..d36043b99dc6 100644
--- a/arch/x86/entry/vdso/vsgx_enter_enclave.S
+++ b/arch/x86/entry/vdso/vsgx_enter_enclave.S
@@ -142,10 +142,10 @@ ENTRY(__vdso_sgx_enter_enclave)
 
 	/*
 	 * Align stack per x86_64 ABI. Note, %rsp needs to be 16-byte aligned
-	 * _after_ pushing the three parameters on the stack.
+	 * _after_ pushing the parameters on the stack, hence the bonus push.
 	 */
 	and	$-0x10, %rsp
-	sub	$0x8, %rsp
+	push	%rax
 
 	/* Push @e, the "return" value and @tcs as params to the callback. */
 	push	0x18(%rbp)
-- 
2.22.0




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