[PATCH v2 29/44] cpuidle,tdx: Make tdx noinstr clean

Peter Zijlstra
2022-09-19T10:00:08Z

vmlinux.o: warning: objtool: __halt+0x2c: call to hcall_func.constprop.0() leaves .noinstr.text section
vmlinux.o: warning: objtool: __halt+0x3f: call to __tdx_hypercall() leaves .noinstr.text section
vmlinux.o: warning: objtool: __tdx_hypercall+0x66: call to __tdx_hypercall_failed() leaves .noinstr.text section

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/boot/compressed/vmlinux.lds.S | 1 +
arch/x86/coco/tdx/tdcall.S | 2 ++
arch/x86/coco/tdx/tdx.c | 5 +++--
3 files changed, 6 insertions(+), 2 deletions(-)

--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -34,6 +34,7 @@ SECTIONS
_text = .; /* Text */
*(.text)
*(.text.*)
+ *(.noinstr.text)
_etext = . ;
}
.rodata : {
--- a/arch/x86/coco/tdx/tdcall.S
+++ b/arch/x86/coco/tdx/tdcall.S
@@ -31,6 +31,8 @@
TDX_R12 | TDX_R13 | \
TDX_R14 | TDX_R15 )

+.section .noinstr.text, "ax"
+
/*
* __tdx_module_call() - Used by TDX guests to request services from
* the TDX module (does not include VMM services) using TDCALL instruction.
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -53,8 +53,9 @@ static inline u64 _tdx_hypercall(u64 fn,
}

/* Called from __tdx_hypercall() for unrecoverable failure */
-void __tdx_hypercall_failed(void)
+noinstr void __tdx_hypercall_failed(void)
{
+ instrumentation_begin();
panic("TDVMCALL failed. TDX module bug?");
}

@@ -64,7 +65,7 @@ void __tdx_hypercall_failed(void)
* Reusing the KVM EXIT_REASON macros makes it easier to connect the host and
* guest sides of these calls.
*/
-static u64 hcall_func(u64 exit_reason)
+static __always_inline u64 hcall_func(u64 exit_reason)
{
return exit_reason;
}