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cpuidle, tdx: Make TDX code noinstr clean

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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
This commit is contained in:
Peter Zijlstra 2023-01-12 20:43:43 +01:00 committed by Ingo Molnar
parent 2ec8efe64e
commit c3982c1a36
3 changed files with 6 additions and 2 deletions
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1
arch/x86/boot/compressed/vmlinux.lds.S
View file

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

2
arch/x86/coco/tdx/tdcall.S
View file

@ -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.

5
arch/x86/coco/tdx/tdx.c
View file

@ -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;
}