[tip: x86/sgx] selftests/sgx: Remove incomplete ABI sanitization code in test enclave

[tip-bot2 for Jo Van Bulck]

The following commit has been merged into the x86/sgx branch of tip:

Commit-ID:     886c5be0b12e89b2905c26c4f24d50ae91f261da
Gitweb:        https://git.kernel.org/tip/886c5be0b12e89b2905c26c4f24d50ae91f261da
Author:        Jo Van Bulck <jo.vanbulck@xxxxxxxxxxxxxx>
AuthorDate:    Thu, 05 Oct 2023 17:38:54 +02:00
Committer:     Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Fri, 08 Dec 2023 10:05:28 -08:00

selftests/sgx: Remove incomplete ABI sanitization code in test enclave

As the selftest enclave is *not* intended for production, simplify the
code by not initializing CPU configuration registers as expected by the
ABI on enclave entry or cleansing caller-save registers on enclave exit.

Signed-off-by: Jo Van Bulck <jo.vanbulck@xxxxxxxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
Link: https://lore.kernel.org/all/da0cfb1e-e347-f7f2-ac72-aec0ee0d867d@xxxxxxxxx/
Link: https://lore.kernel.org/all/20231005153854.25566-14-jo.vanbulck%40cs.kuleuven.be
---
 tools/testing/selftests/sgx/test_encl_bootstrap.S | 16 ++------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/sgx/test_encl_bootstrap.S b/tools/testing/selftests/sgx/test_encl_bootstrap.S
index 28fe5d2..d8c4ac9 100644
--- a/tools/testing/selftests/sgx/test_encl_bootstrap.S
+++ b/tools/testing/selftests/sgx/test_encl_bootstrap.S
@@ -59,21 +59,11 @@ encl_entry_core:
 
 	push	%rcx # push the address after EENTER
 
+	# NOTE: as the selftest enclave is *not* intended for production,
+	# simplify the code by not initializing ABI registers on entry or
+	# cleansing caller-save registers on exit.
 	call	encl_body
 
-	/* Clear volatile GPRs, except RAX (EEXIT function). */
-	xor     %rcx, %rcx
-	xor     %rdx, %rdx
-	xor     %rdi, %rdi
-	xor     %rsi, %rsi
-	xor     %r8, %r8
-	xor     %r9, %r9
-	xor     %r10, %r10
-	xor     %r11, %r11
-
-	# Reset status flags.
-	add     %rdx, %rdx # OF = SF = AF = CF = 0; ZF = PF = 1
-
 	# Prepare EEXIT target by popping the address of the instruction after
 	# EENTER to RBX.
 	pop	%rbx