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Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev" [off-list ref]

On Mon, Jun 13, 2022 at 07:23:13PM +0000, Nadav Amit wrote:

On Jun 13, 2022, at 11:48 AM, Srivatsa S. Bhat [off-list ref] wrote:

quoted

⚠ External Email

On 6/8/22 4:27 PM, Peter Zijlstra wrote:

quoted

vmlinux.o: warning: objtool: acpi_idle_enter_s2idle+0xde: call to wbinvd() leaves .noinstr.text section
vmlinux.o: warning: objtool: default_idle+0x4: call to arch_safe_halt() leaves .noinstr.text section
vmlinux.o: warning: objtool: xen_safe_halt+0xa: call to HYPERVISOR_sched_op.constprop.0() leaves .noinstr.text section

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Reviewed-by: Srivatsa S. Bhat (VMware) <redacted>

quoted

-static inline void wbinvd(void)
+extern noinstr void pv_native_wbinvd(void);
+
+static __always_inline void wbinvd(void)
{
     PVOP_ALT_VCALL0(cpu.wbinvd, "wbinvd", ALT_NOT(X86_FEATURE_XENPV));
}

I guess it is yet another instance of wrong accounting of GCC for
the assembly blocks’ weight. I guess it is not a solution for older
GCCs, but presumably ____PVOP_ALT_CALL() and friends should have
used asm_inline or some new “asm_volatile_inline” variant.

Partially, some of the *SAN options also generate a metric ton of
nonsense when enabled and skew the compilers towards not inlining
things.