[PATCH v11 30/37] x86/fred: Let ret_from_fork_asm() jmp to asm_fred_exit_user when FRED is enabled

Xin Li
2023-09-23T10:13:21Z

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 179e08d34eb6..f7db3a12ccb1 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