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Message-Id: <20220719114726.628551296@linuxfoundation.org>
Date: Tue, 19 Jul 2022 13:53:51 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Kim Phillips <kim.phillips@....com>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>,
Borislav Petkov <bp@...e.de>,
Josh Poimboeuf <jpoimboe@...nel.org>,
Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.18 146/231] x86/sev: Avoid using __x86_return_thunk
From: Kim Phillips <kim.phillips@....com>
[ Upstream commit 0ee9073000e8791f8b134a8ded31bcc767f7f232 ]
Specifically, it's because __enc_copy() encrypts the kernel after
being relocated outside the kernel in sme_encrypt_execute(), and the
RET macro's jmp offset isn't amended prior to execution.
Signed-off-by: Kim Phillips <kim.phillips@....com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@...nel.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
arch/x86/mm/mem_encrypt_boot.S | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/x86/mm/mem_encrypt_boot.S b/arch/x86/mm/mem_encrypt_boot.S
index 3d1dba05fce4..d94dea450fa6 100644
--- a/arch/x86/mm/mem_encrypt_boot.S
+++ b/arch/x86/mm/mem_encrypt_boot.S
@@ -65,7 +65,9 @@ SYM_FUNC_START(sme_encrypt_execute)
movq %rbp, %rsp /* Restore original stack pointer */
pop %rbp
- RET
+ /* Offset to __x86_return_thunk would be wrong here */
+ ret
+ int3
SYM_FUNC_END(sme_encrypt_execute)
SYM_FUNC_START(__enc_copy)
@@ -151,6 +153,8 @@ SYM_FUNC_START(__enc_copy)
pop %r12
pop %r15
- RET
+ /* Offset to __x86_return_thunk would be wrong here */
+ ret
+ int3
.L__enc_copy_end:
SYM_FUNC_END(__enc_copy)
--
2.35.1
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