[PATCH v10 30/38] x86/fred: Let ret_from_fork_asm() jmp to asm_fred_exit_user when FRED is enabled

[Xin Li <xin3.li@xxxxxxxxx>]

From: "H. Peter Anvin (Intel)" <hpa@xxxxxxxxx>

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@xxxxxxxxx>
Tested-by: Shan Kang <shan.kang@xxxxxxxxx>
Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
---
 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 9cdb61ea91de..c9e14617dd3f 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -309,7 +309,13 @@ 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)
-- 
2.34.1