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Date: Fri, 26 Aug 2022 16:03:28 -0400 (EDT)
From: Mikulas Patocka <mpatocka@...hat.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>,
Brian Cain <bcain@...cinc.com>, linux-hexagon@...r.kernel.org
cc: Linus Torvalds <torvalds@...ux-foundation.org>,
Alan Stern <stern@...land.harvard.edu>,
Andrea Parri <parri.andrea@...il.com>,
Will Deacon <will@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Boqun Feng <boqun.feng@...il.com>,
Nicholas Piggin <npiggin@...il.com>,
David Howells <dhowells@...hat.com>,
Jade Alglave <j.alglave@....ac.uk>,
Luc Maranget <luc.maranget@...ia.fr>,
"Paul E. McKenney" <paulmck@...nel.org>,
Akira Yokosawa <akiyks@...il.com>,
Daniel Lustig <dlustig@...dia.com>,
Joel Fernandes <joel@...lfernandes.org>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Linux-Arch <linux-arch@...r.kernel.org>
Subject: [PATCH] provide arch_test_bit_acquire for architectures that define
test_bit
On Fri, 26 Aug 2022, Geert Uytterhoeven wrote:
> Hi Mikulas,
>
> noreply@...erman.id.au reports lots of build failures on m68k:
>
> include/asm-generic/bitops/non-instrumented-non-atomic.h:15:33:
> error: implicit declaration of function 'arch_test_bit_acquire'; did
> you mean '_test_bit_acquire'? [-Werror=implicit-function-declaration]
>
> which I've bisected to this commit.
>
> http://kisskb.ellerman.id.au/kisskb/head/3e5c673f0d75bc22b3c26eade87e4db4f374cd34
Does this patch fix it? It is untested.
I'm not sure about the hexagon architecture, it is presumably in-order so
that test_bit and test_bit_acquire are equivalent, but I am not sure about
that - I'm adding hexagon maintainer to the recipient field.
Mikulas
provide arch_test_bit_acquire for architectures that define test_bit
Some architectures define their own arch_test_bit and they also need
arch_test_bit_acquire, otherwise they won't compile.
Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
Cc: stable@...r.kernel.org
Fixes: 8238b4579866 ("wait_on_bit: add an acquire memory barrier")
---
arch/alpha/include/asm/bitops.h | 7 +++++++
arch/hexagon/include/asm/bitops.h | 15 +++++++++++++++
arch/ia64/include/asm/bitops.h | 7 +++++++
arch/m68k/include/asm/bitops.h | 7 +++++++
arch/s390/include/asm/bitops.h | 7 +++++++
5 files changed, 43 insertions(+)
Index: linux-2.6/arch/m68k/include/asm/bitops.h
===================================================================
--- linux-2.6.orig/arch/m68k/include/asm/bitops.h
+++ linux-2.6/arch/m68k/include/asm/bitops.h
@@ -163,6 +163,13 @@ arch_test_bit(unsigned long nr, const vo
return (addr[nr >> 5] & (1UL << (nr & 31))) != 0;
}
+static __always_inline bool
+arch_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr)
+{
+ unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+ return 1UL & (smp_load_acquire(p) >> (nr & (BITS_PER_LONG-1)));
+}
+
static inline int bset_reg_test_and_set_bit(int nr,
volatile unsigned long *vaddr)
{
Index: linux-2.6/arch/alpha/include/asm/bitops.h
===================================================================
--- linux-2.6.orig/arch/alpha/include/asm/bitops.h
+++ linux-2.6/arch/alpha/include/asm/bitops.h
@@ -289,6 +289,13 @@ arch_test_bit(unsigned long nr, const vo
return (1UL & (((const int *) addr)[nr >> 5] >> (nr & 31))) != 0UL;
}
+static __always_inline bool
+arch_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr)
+{
+ unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+ return 1UL & (smp_load_acquire(p) >> (nr & (BITS_PER_LONG-1)));
+}
+
/*
* ffz = Find First Zero in word. Undefined if no zero exists,
* so code should check against ~0UL first..
Index: linux-2.6/arch/hexagon/include/asm/bitops.h
===================================================================
--- linux-2.6.orig/arch/hexagon/include/asm/bitops.h
+++ linux-2.6/arch/hexagon/include/asm/bitops.h
@@ -179,6 +179,21 @@ arch_test_bit(unsigned long nr, const vo
return retval;
}
+static __always_inline bool
+arch_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr)
+{
+ int retval;
+
+ asm volatile(
+ "{P0 = tstbit(%1,%2); if (P0.new) %0 = #1; if (!P0.new) %0 = #0;}\n"
+ : "=&r" (retval)
+ : "r" (addr[BIT_WORD(nr)]), "r" (nr % BITS_PER_LONG)
+ : "p0", "memory"
+ );
+
+ return retval;
+}
+
/*
* ffz - find first zero in word.
* @word: The word to search
Index: linux-2.6/arch/ia64/include/asm/bitops.h
===================================================================
--- linux-2.6.orig/arch/ia64/include/asm/bitops.h
+++ linux-2.6/arch/ia64/include/asm/bitops.h
@@ -337,6 +337,13 @@ arch_test_bit(unsigned long nr, const vo
return 1 & (((const volatile __u32 *) addr)[nr >> 5] >> (nr & 31));
}
+static __always_inline bool
+arch_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr)
+{
+ unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+ return 1UL & (smp_load_acquire(p) >> (nr & (BITS_PER_LONG-1)));
+}
+
/**
* ffz - find the first zero bit in a long word
* @x: The long word to find the bit in
Index: linux-2.6/arch/s390/include/asm/bitops.h
===================================================================
--- linux-2.6.orig/arch/s390/include/asm/bitops.h
+++ linux-2.6/arch/s390/include/asm/bitops.h
@@ -185,6 +185,13 @@ arch_test_bit(unsigned long nr, const vo
return *p & mask;
}
+static __always_inline bool
+arch_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr)
+{
+ unsigned long *p = ((unsigned long *)addr) + BIT_WORD(nr);
+ return 1UL & (smp_load_acquire(p) >> (nr & (BITS_PER_LONG-1)));
+}
+
static inline bool arch_test_and_set_bit_lock(unsigned long nr,
volatile unsigned long *ptr)
{
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