Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Arvind Sankar <nivedita@alum.mit.edu>
To:     Ard Biesheuvel <ardb@kernel.org>
Cc:     linux-efi@vger.kernel.org, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 2/5] efi/x86: Respect 32-bit ABI in efi32_pe_entry
Date:   Sun,  1 Mar 2020 18:04:33 -0500
Message-Id: <20200301230436.2246909-3-nivedita@alum.mit.edu>
In-Reply-To: <20200301230436.2246909-1-nivedita@alum.mit.edu>
References: <20200301230436.2246909-1-nivedita@alum.mit.edu>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

verify_cpu clobbers BX and DI. In case we have to return error, we need
to preserve them to respect 32-bit calling convention.

Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
---
 arch/x86/boot/compressed/head_64.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index 8105e8348607..920daf62dac2 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -660,7 +660,11 @@ SYM_DATA(efi_is64, .byte 1)
 SYM_FUNC_START(efi32_pe_entry)
 	pushl	%ebp
 
+	pushl	%ebx
+	pushl	%edi
 	call	verify_cpu			// check for long mode support
+	popl	%edi
+	popl	%ebx
 	testl	%eax, %eax
 	movl	$0x80000003, %eax		// EFI_UNSUPPORTED
 	jnz	3f
-- 
2.24.1