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authorThomas Gleixner <tglx@linutronix.de>2020-12-15 10:48:07 +0100
committerThomas Gleixner <tglx@linutronix.de>2020-12-15 10:48:07 +0100
commit3c41e57a1e168d879e923c5583adeae47eec9f64 (patch)
treee6272012c4b766189be2821316a3d23d115f5195 /include/linux/compiler.h
parentirq: Call tick_irq_enter() inside HARDIRQ_OFFSET (diff)
parentirqchip/qcom-pdc: Fix phantom irq when changing between rising/falling (diff)
downloadwireguard-linux-3c41e57a1e168d879e923c5583adeae47eec9f64.tar.xz
wireguard-linux-3c41e57a1e168d879e923c5583adeae47eec9f64.zip
Merge tag 'irqchip-5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/core
Pull irqchip updates for 5.11 from Marc Zyngier: - Preliminary support for managed interrupts on platform devices - Correctly identify allocation of MSIs proxyied by another device - Remove the fasteoi IPI flow which has been proved useless - Generalise the Ocelot support to new SoCs - Improve GICv4.1 vcpu entry, matching the corresponding KVM optimisation - Work around spurious interrupts on Qualcomm PDC - Random fixes and cleanups Link: https://lore.kernel.org/r/20201212135626.1479884-1-maz@kernel.org
Diffstat (limited to 'include/linux/compiler.h')
-rw-r--r--include/linux/compiler.h18
1 files changed, 16 insertions, 2 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index e512f5505dad..b8fe0c23cfff 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -80,11 +80,25 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
/* Optimization barrier */
#ifndef barrier
-# define barrier() __memory_barrier()
+/* The "volatile" is due to gcc bugs */
+# define barrier() __asm__ __volatile__("": : :"memory")
#endif
#ifndef barrier_data
-# define barrier_data(ptr) barrier()
+/*
+ * This version is i.e. to prevent dead stores elimination on @ptr
+ * where gcc and llvm may behave differently when otherwise using
+ * normal barrier(): while gcc behavior gets along with a normal
+ * barrier(), llvm needs an explicit input variable to be assumed
+ * clobbered. The issue is as follows: while the inline asm might
+ * access any memory it wants, the compiler could have fit all of
+ * @ptr into memory registers instead, and since @ptr never escaped
+ * from that, it proved that the inline asm wasn't touching any of
+ * it. This version works well with both compilers, i.e. we're telling
+ * the compiler that the inline asm absolutely may see the contents
+ * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
+ */
+# define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
#endif
/* workaround for GCC PR82365 if needed */