Commit c3982c1a authored Jan 12, 2023 by Peter Zijlstra Committed by Ingo Molnar Jan 13, 2023

cpuidle, tdx: Make TDX code noinstr clean



objtool found a few cases where this code called out into instrumented
code:

  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

Fix it by:

  - moving TDX tdcall assembly methods into .noinstr.text (they are already noistr-clean)
  - marking __tdx_hypercall_failed() as 'noinstr'
  - annotating hcall_func() as __always_inline

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Tony Lindgren <tony@atomide.com>
Tested-by: Ulf Hansson <ulf.hansson@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20230112195541.111485720@infradead.org

parent 2ec8efe6

arch/x86/boot/compressed/vmlinux.lds.S

+1 −0

Original line number	Diff line number	Diff line
		@@ -34,6 +34,7 @@ SECTIONS
		_text = .; /* Text */
		*(.text)
		(.text.)
		*(.noinstr.text)
		_etext = . ;
		}
		.rodata : {

arch/x86/coco/tdx/tdcall.S

+2 −0

Original line number	Diff line number	Diff line
		@@ -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.

arch/x86/coco/tdx/tdx.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -64,8 +64,9 @@ static inline u64 _tdx_hypercall(u64 fn, u64 r12, u64 r13, u64 r14, u64 r15)
		}

		/* 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?");
		}

		@@ -75,7 +76,7 @@ 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;
		}