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From:   Xin Li <xin3.li@intel.com>
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Subject: [PATCH v13 28/35] x86/fred: Let ret_from_fork_asm() jmp to asm_fred_exit_user when FRED is enabled
Date:   Tue,  5 Dec 2023 02:50:17 -0800
Message-ID: <20231205105030.8698-29-xin3.li@intel.com>
In-Reply-To: <20231205105030.8698-1-xin3.li@intel.com>
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From: "H. Peter Anvin (Intel)" <hpa@zytor.com>

Let ret_from_fork_asm() jmp to asm_fred_exit_user when FRED is enabled,
otherwise the existing IDT code is chosen.

Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
Tested-by: Shan Kang <shan.kang@intel.com>
Signed-off-by: Xin Li <xin3.li@intel.com>
---
 arch/x86/entry/entry_64.S      | 6 ++++++
 arch/x86/entry/entry_64_fred.S | 1 +
 2 files changed, 7 insertions(+)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 5a1660701623..87d817296dcb 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -247,7 +247,13 @@ SYM_CODE_START(ret_from_fork_asm)
 	 * and unwind should work normally.
 	 */
 	UNWIND_HINT_REGS
+
+#ifdef CONFIG_X86_FRED
+	ALTERNATIVE "jmp swapgs_restore_regs_and_return_to_usermode", \
+		    "jmp asm_fred_exit_user", X86_FEATURE_FRED
+#else
 	jmp	swapgs_restore_regs_and_return_to_usermode
+#endif
 SYM_CODE_END(ret_from_fork_asm)
 .popsection
 
diff --git a/arch/x86/entry/entry_64_fred.S b/arch/x86/entry/entry_64_fred.S
index 37a1dd5e8ace..5781c3411b44 100644
--- a/arch/x86/entry/entry_64_fred.S
+++ b/arch/x86/entry/entry_64_fred.S
@@ -32,6 +32,7 @@
 SYM_CODE_START_NOALIGN(asm_fred_entrypoint_user)
 	FRED_ENTER
 	call	fred_entry_from_user
+SYM_INNER_LABEL(asm_fred_exit_user, SYM_L_GLOBAL)
 	FRED_EXIT
 	ERETU
 SYM_CODE_END(asm_fred_entrypoint_user)
-- 
2.43.0