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[xen master] xen/ppc: Implement atomic.h



commit 6aa25c32180ab59081c73bae4c568367d9133a1f
Author:     Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>
AuthorDate: Wed Sep 13 09:50:07 2023 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Sep 13 09:50:07 2023 +0200

    xen/ppc: Implement atomic.h
    
    Implement atomic.h for PPC, based off of the original Xen 3.2
    implementation. This implementation depends on some functions that are
    not yet defined (notably __cmpxchg), so it can't yet be used.
    
    Signed-off-by: Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/ppc/include/asm/atomic.h | 385 ++++++++++++++++++++++++++++++++++++++
 xen/arch/ppc/include/asm/memory.h |  14 ++
 2 files changed, 399 insertions(+)

diff --git a/xen/arch/ppc/include/asm/atomic.h 
b/xen/arch/ppc/include/asm/atomic.h
new file mode 100644
index 0000000000..64168aa3f1
--- /dev/null
+++ b/xen/arch/ppc/include/asm/atomic.h
@@ -0,0 +1,385 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * PowerPC64 atomic operations
+ *
+ * Copyright (C) 2001 Paul Mackerras <paulus@xxxxxxxxxx>, IBM
+ * Copyright (C) 2001 Anton Blanchard <anton@xxxxxxxxxx>, IBM
+ * Copyright Raptor Engineering LLC
+ */
+
+#ifndef _ASM_PPC64_ATOMIC_H_
+#define _ASM_PPC64_ATOMIC_H_
+
+#include <xen/atomic.h>
+
+#include <asm/memory.h>
+
+static inline int atomic_read(const atomic_t *v)
+{
+    return *(volatile int *)&v->counter;
+}
+
+static inline int _atomic_read(atomic_t v)
+{
+    return v.counter;
+}
+
+static inline void atomic_set(atomic_t *v, int i)
+{
+    v->counter = i;
+}
+
+static inline void _atomic_set(atomic_t *v, int i)
+{
+    v->counter = i;
+}
+
+void __bad_atomic_read(const volatile void *p, void *res);
+void __bad_atomic_size(void);
+
+#define build_atomic_read(name, insn, type)                                    
\
+    static inline type name(const volatile type *addr)                         
\
+    {                                                                          
\
+        type ret;                                                              
\
+        asm volatile ( insn "%U1%X1 %0,%1" : "=r" (ret) : "m<>" (*addr) );     
\
+        return ret;                                                            
\
+    }
+
+#define build_atomic_write(name, insn, type)                                   
\
+    static inline void name(volatile type *addr, type val)                     
\
+    {                                                                          
\
+        asm volatile ( insn "%U0%X0 %1,%0" : "=m<>" (*addr) : "r" (val) );     
\
+    }
+
+#define build_add_sized(name, ldinsn, stinsn, type)                            
\
+    static inline void name(volatile type *addr, type val)                     
\
+    {                                                                          
\
+        type t;                                                                
\
+        asm volatile ( "1: " ldinsn " %0,0,%3\n"                               
\
+                       "add%I2 %0,%0,%2\n"                                     
\
+                       stinsn " %0,0,%3 \n"                                    
\
+                       "bne- 1b\n"                                             
\
+                       : "=&r" (t), "+m" (*addr)                               
\
+                       : "r" (val), "r" (addr)                                 
\
+                       : "cc" );                                               
\
+    }
+
+build_atomic_read(read_u8_atomic, "lbz", uint8_t)
+build_atomic_read(read_u16_atomic, "lhz", uint16_t)
+build_atomic_read(read_u32_atomic, "lwz", uint32_t)
+build_atomic_read(read_u64_atomic, "ldz", uint64_t)
+
+build_atomic_write(write_u8_atomic, "stb", uint8_t)
+build_atomic_write(write_u16_atomic, "sth", uint16_t)
+build_atomic_write(write_u32_atomic, "stw", uint32_t)
+build_atomic_write(write_u64_atomic, "std", uint64_t)
+
+build_add_sized(add_u8_sized, "lbarx", "stbcx.",uint8_t)
+build_add_sized(add_u16_sized, "lharx", "sthcx.", uint16_t)
+build_add_sized(add_u32_sized, "lwarx", "stwcx.", uint32_t)
+
+#undef build_atomic_read
+#undef build_atomic_write
+#undef build_add_sized
+
+static always_inline void read_atomic_size(const volatile void *p, void *res,
+                                           unsigned int size)
+{
+    ASSERT(IS_ALIGNED((vaddr_t)p, size));
+    switch ( size )
+    {
+    case 1:
+        *(uint8_t *)res = read_u8_atomic(p);
+        break;
+    case 2:
+        *(uint16_t *)res = read_u16_atomic(p);
+        break;
+    case 4:
+        *(uint32_t *)res = read_u32_atomic(p);
+        break;
+    case 8:
+        *(uint64_t *)res = read_u64_atomic(p);
+        break;
+    default:
+        __bad_atomic_read(p, res);
+        break;
+    }
+}
+
+static always_inline void write_atomic_size(volatile void *p, const void *val,
+                                            unsigned int size)
+{
+    ASSERT(IS_ALIGNED((vaddr_t)p, size));
+    switch ( size )
+    {
+    case 1:
+        write_u8_atomic(p, *(const uint8_t *)val);
+        break;
+    case 2:
+        write_u16_atomic(p, *(const uint16_t *)val);
+        break;
+    case 4:
+        write_u32_atomic(p, *(const uint32_t *)val);
+        break;
+    case 8:
+        write_u64_atomic(p, *(const uint64_t *)val);
+        break;
+    default:
+        __bad_atomic_size();
+        break;
+    }
+}
+
+#define read_atomic(p)                                                         
\
+    ({                                                                         
\
+        union {                                                                
\
+            typeof(*(p)) val;                                                  
\
+            char c[sizeof(*(p))];                                              
\
+        } x_;                                                                  
\
+        read_atomic_size(p, x_.c, sizeof(*(p)));                               
\
+        x_.val;                                                                
\
+    })
+
+#define write_atomic(p, x)                                                     
\
+    do                                                                         
\
+    {                                                                          
\
+        typeof(*(p)) x_ = (x);                                                 
\
+        write_atomic_size(p, &x_, sizeof(*(p)));                               
\
+    } while ( 0 )
+
+#define add_sized(p, x)                                                        
\
+    ({                                                                         
\
+        typeof(*(p)) x_ = (x);                                                 
\
+        switch ( sizeof(*(p)) )                                                
\
+        {                                                                      
\
+        case 1:                                                                
\
+            add_u8_sized((uint8_t *)(p), x_);                                  
\
+            break;                                                             
\
+        case 2:                                                                
\
+            add_u16_sized((uint16_t *)(p), x_);                                
\
+            break;                                                             
\
+        case 4:                                                                
\
+            add_u32_sized((uint32_t *)(p), x_);                                
\
+            break;                                                             
\
+        default:                                                               
\
+            __bad_atomic_size();                                               
\
+            break;                                                             
\
+        }                                                                      
\
+    })
+
+static inline void atomic_add(int a, atomic_t *v)
+{
+    int t;
+
+    asm volatile ( "1: lwarx %0,0,%3\n"
+                   "add %0,%2,%0\n"
+                   "stwcx. %0,0,%3\n"
+                   "bne- 1b"
+                   : "=&r" (t), "+m" (v->counter)
+                   : "r" (a), "r" (&v->counter)
+                   : "cc" );
+}
+
+static inline int atomic_add_return(int a, atomic_t *v)
+{
+    int t;
+
+    asm volatile ( PPC_ATOMIC_ENTRY_BARRIER
+                   "1: lwarx %0,0,%2\n"
+                   "add %0,%1,%0\n"
+                   "stwcx. %0,0,%2\n"
+                   "bne- 1b\n"
+                   PPC_ATOMIC_EXIT_BARRIER
+                   : "=&r" (t)
+                   : "r" (a), "r" (&v->counter)
+                   : "cc", "memory" );
+
+    return t;
+}
+
+static inline void atomic_sub(int a, atomic_t *v)
+{
+    int t;
+
+    asm volatile ( "1: lwarx %0,0,%3\n"
+                   "subf %0,%2,%0\n"
+                   "stwcx. %0,0,%3\n"
+                   "bne- 1b"
+                   : "=&r" (t), "+m" (v->counter)
+                   : "r" (a), "r" (&v->counter)
+                   : "cc" );
+}
+
+static inline int atomic_sub_return(int a, atomic_t *v)
+{
+    int t;
+
+    asm volatile ( PPC_ATOMIC_ENTRY_BARRIER
+                   "1: lwarx %0,0,%2\n"
+                   "subf %0,%1,%0\n"
+                   "stwcx. %0,0,%2\n"
+                   "bne- 1b\n"
+                   PPC_ATOMIC_EXIT_BARRIER
+                   : "=&r" (t)
+                   : "r" (a), "r" (&v->counter)
+                   : "cc", "memory" );
+
+    return t;
+}
+
+static inline void atomic_inc(atomic_t *v)
+{
+    int t;
+
+    asm volatile ( "1: lwarx %0,0,%2\n"
+                   "addic %0,%0,1\n"
+                   "stwcx. %0,0,%2\n"
+                   "bne- 1b"
+                   : "=&r" (t), "+m" (v->counter)
+                   : "r" (&v->counter)
+                   : "cc" );
+}
+
+static inline int atomic_inc_return(atomic_t *v)
+{
+    int t;
+
+    asm volatile ( PPC_ATOMIC_ENTRY_BARRIER
+                   "1: lwarx %0,0,%1\n"
+                   "addic %0,%0,1\n"
+                   "stwcx. %0,0,%1\n"
+                   "bne- 1b\n"
+                   PPC_ATOMIC_EXIT_BARRIER
+                   : "=&r" (t)
+                   : "r" (&v->counter)
+                   : "cc", "memory" );
+
+    return t;
+}
+
+static inline void atomic_dec(atomic_t *v)
+{
+    int t;
+
+    asm volatile ( "1: lwarx %0,0,%2\n"
+                   "addic %0,%0,-1\n"
+                   "stwcx. %0,0,%2\n"
+                   "bne- 1b"
+                   : "=&r" (t), "+m" (v->counter)
+                   : "r" (&v->counter)
+                   : "cc" );
+}
+
+static inline int atomic_dec_return(atomic_t *v)
+{
+    int t;
+
+    asm volatile ( PPC_ATOMIC_ENTRY_BARRIER
+                   "1: lwarx %0,0,%1\n"
+                   "addic %0,%0,-1\n"
+                   "stwcx. %0,0,%1\n"
+                   "bne- 1b\n"
+                   PPC_ATOMIC_EXIT_BARRIER
+                   : "=&r" (t)
+                   : "r" (&v->counter)
+                   : "cc", "memory" );
+
+    return t;
+}
+
+/*
+ * Atomically test *v and decrement if it is greater than 0.
+ * The function returns the old value of *v minus 1.
+ */
+static inline int atomic_dec_if_positive(atomic_t *v)
+{
+    int t;
+
+    asm volatile( PPC_ATOMIC_ENTRY_BARRIER
+                  "1: lwarx %0,0,%1 # atomic_dec_if_positive\n"
+                  "addic. %0,%0,-1\n"
+                  "blt- 2f\n"
+                  "stwcx. %0,0,%1\n"
+                  "bne- 1b\n"
+                  PPC_ATOMIC_EXIT_BARRIER
+                  "2:"
+                  : "=&r" (t)
+                  : "r" (&v->counter)
+                  : "cc", "memory" );
+
+    return t;
+}
+
+static inline atomic_t atomic_compareandswap(atomic_t old, atomic_t new,
+                                             atomic_t *v)
+{
+    atomic_t rc;
+    rc.counter = __cmpxchg(&v->counter, old.counter, new.counter,
+                           sizeof(v->counter));
+    return rc;
+}
+
+#define arch_cmpxchg(ptr, o, n)                                                
\
+    ({                                                                         
\
+        __typeof__(*(ptr)) o_ = (o);                                           
\
+        __typeof__(*(ptr)) n_ = (n);                                           
\
+        (__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)o_,               
\
+                                       (unsigned long)n_, sizeof(*(ptr)));     
\
+    })
+
+static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
+{
+    return arch_cmpxchg(&v->counter, old, new);
+}
+
+#define ATOMIC_OP(op, insn, suffix, sign) \
+    static inline void atomic_##op(int a, atomic_t *v)                         
  \
+    {                                                                          
  \
+        int t;                                                                 
  \
+        asm volatile ( "1: lwarx %0,0,%3\n"                                    
  \
+                       insn "%I2" suffix " %0,%0,%2\n"                         
  \
+                       "stwcx. %0,0,%3 \n"                                     
  \
+                       "bne- 1b\n"                                             
  \
+                       : "=&r" (t), "+m" (v->counter)                          
  \
+                       : "r" #sign (a), "r" (&v->counter)                      
  \
+                       : "cc" );                                               
  \
+    }
+
+ATOMIC_OP(and, "and", ".", K)
+
+static inline int atomic_sub_and_test(int i, atomic_t *v)
+{
+    return atomic_sub_return(i, v) == 0;
+}
+
+static inline int atomic_inc_and_test(atomic_t *v)
+{
+    return atomic_add_return(1, v) == 0;
+}
+
+static inline int atomic_dec_and_test(atomic_t *v)
+{
+    return atomic_sub_return(1, v) == 0;
+}
+
+static inline int atomic_add_negative(int i, atomic_t *v)
+{
+    return atomic_add_return(i, v) < 0;
+}
+
+static inline int __atomic_add_unless(atomic_t *v, int a, int u)
+{
+       int c, old;
+
+       c = atomic_read(v);
+       while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
+               c = old;
+       return c;
+}
+
+static inline int atomic_add_unless(atomic_t *v, int a, int u)
+{
+    return __atomic_add_unless(v, a, u);
+}
+
+#endif /* _ASM_PPC64_ATOMIC_H_ */
diff --git a/xen/arch/ppc/include/asm/memory.h 
b/xen/arch/ppc/include/asm/memory.h
new file mode 100644
index 0000000000..57310eb690
--- /dev/null
+++ b/xen/arch/ppc/include/asm/memory.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) IBM Corp. 2005
+ *
+ * Authors: Jimi Xenidis <jimix@xxxxxxxxxxxxxx>
+ */
+
+#ifndef _ASM_MEMORY_H_
+#define _ASM_MEMORY_H_
+
+#define PPC_ATOMIC_ENTRY_BARRIER "sync\n"
+#define PPC_ATOMIC_EXIT_BARRIER  "sync\n"
+
+#endif
--
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