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authorJoel Fernandes <joelagnelf@nvidia.com>2026-07-18 13:15:36 -0400
committerPaul E. McKenney <paulmck@kernel.org>2026-07-23 10:39:57 -0700
commit34ff636f322c6d5e4f0a52338fa63a7dff09a495 (patch)
tree7629759c1ec7148b95bc8ab3080df20a5ecd2273 /arch/alpha/lib/divide.S
downloadlinux-stable-34ff636f322c6d5e4f0a52338fa63a7dff09a495.tar.gz
linux-stable-34ff636f322c6d5e4f0a52338fa63a7dff09a495.zip
scftorture: Count single_rpc offline failures in statistics outputgrafted
scf_torture_stats_print() aggregates each invoker thread's counters into a local scf_statistics structure before printing, but the n_single_rpc_ofl field is missing from the aggregation loop. As a result, the "single_rpc_ofl" value printed in the statistics line is always zero, even when smp_call_function_single() invocations for the RPC test have failed due to offline CPUs and been counted by the invoker threads. Add the missing accumulation so that the printed value reflects the actual counts. Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'arch/alpha/lib/divide.S')
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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * arch/alpha/lib/divide.S
+ *
+ * (C) 1995 Linus Torvalds
+ *
+ * Alpha division..
+ */
+
+/*
+ * The alpha chip doesn't provide hardware division, so we have to do it
+ * by hand. The compiler expects the functions
+ *
+ * __divqu: 64-bit unsigned long divide
+ * __remqu: 64-bit unsigned long remainder
+ * __divqs/__remqs: signed 64-bit
+ * __divlu/__remlu: unsigned 32-bit
+ * __divls/__remls: signed 32-bit
+ *
+ * These are not normal C functions: instead of the normal
+ * calling sequence, these expect their arguments in registers
+ * $24 and $25, and return the result in $27. Register $28 may
+ * be clobbered (assembly temporary), anything else must be saved.
+ *
+ * In short: painful.
+ *
+ * This is a rather simple bit-at-a-time algorithm: it's very good
+ * at dividing random 64-bit numbers, but the more usual case where
+ * the divisor is small is handled better by the DEC algorithm
+ * using lookup tables. This uses much less memory, though, and is
+ * nicer on the cache.. Besides, I don't know the copyright status
+ * of the DEC code.
+ */
+
+/*
+ * My temporaries:
+ * $0 - current bit
+ * $1 - shifted divisor
+ * $2 - modulus/quotient
+ *
+ * $23 - return address
+ * $24 - dividend
+ * $25 - divisor
+ *
+ * $27 - quotient/modulus
+ * $28 - compare status
+ */
+
+#include <linux/export.h>
+#define halt .long 0
+
+/*
+ * Select function type and registers
+ */
+#define mask $0
+#define divisor $1
+#define compare $28
+#define tmp1 $3
+#define tmp2 $4
+
+#ifdef DIV
+#define DIV_ONLY(x,y...) x,##y
+#define MOD_ONLY(x,y...)
+#define func(x) __div##x
+#define modulus $2
+#define quotient $27
+#define GETSIGN(x) xor $24,$25,x
+#define STACK 48
+#else
+#define DIV_ONLY(x,y...)
+#define MOD_ONLY(x,y...) x,##y
+#define func(x) __rem##x
+#define modulus $27
+#define quotient $2
+#define GETSIGN(x) bis $24,$24,x
+#define STACK 32
+#endif
+
+/*
+ * For 32-bit operations, we need to extend to 64-bit
+ */
+#ifdef INTSIZE
+#define ufunction func(lu)
+#define sfunction func(l)
+#define LONGIFY(x) zapnot x,15,x
+#define SLONGIFY(x) addl x,0,x
+#else
+#define ufunction func(qu)
+#define sfunction func(q)
+#define LONGIFY(x)
+#define SLONGIFY(x)
+#endif
+
+.set noat
+.align 3
+.globl ufunction
+.ent ufunction
+ufunction:
+ subq $30,STACK,$30
+ .frame $30,STACK,$23
+ .prologue 0
+
+7: stq $1, 0($30)
+ bis $25,$25,divisor
+ stq $2, 8($30)
+ bis $24,$24,modulus
+ stq $0,16($30)
+ bis $31,$31,quotient
+ LONGIFY(divisor)
+ stq tmp1,24($30)
+ LONGIFY(modulus)
+ bis $31,1,mask
+ DIV_ONLY(stq tmp2,32($30))
+ beq divisor, 9f /* div by zero */
+
+#ifdef INTSIZE
+ /*
+ * shift divisor left, using 3-bit shifts for
+ * 32-bit divides as we can't overflow. Three-bit
+ * shifts will result in looping three times less
+ * here, but can result in two loops more later.
+ * Thus using a large shift isn't worth it (and
+ * s8add pairs better than a sll..)
+ */
+1: cmpult divisor,modulus,compare
+ s8addq divisor,$31,divisor
+ s8addq mask,$31,mask
+ bne compare,1b
+#else
+1: cmpult divisor,modulus,compare
+ blt divisor, 2f
+ addq divisor,divisor,divisor
+ addq mask,mask,mask
+ bne compare,1b
+ unop
+#endif
+
+ /* ok, start to go right again.. */
+2: DIV_ONLY(addq quotient,mask,tmp2)
+ srl mask,1,mask
+ cmpule divisor,modulus,compare
+ subq modulus,divisor,tmp1
+ DIV_ONLY(cmovne compare,tmp2,quotient)
+ srl divisor,1,divisor
+ cmovne compare,tmp1,modulus
+ bne mask,2b
+
+9: ldq $1, 0($30)
+ ldq $2, 8($30)
+ ldq $0,16($30)
+ ldq tmp1,24($30)
+ DIV_ONLY(ldq tmp2,32($30))
+ addq $30,STACK,$30
+ ret $31,($23),1
+ .end ufunction
+EXPORT_SYMBOL(ufunction)
+
+/*
+ * Uhh.. Ugly signed division. I'd rather not have it at all, but
+ * it's needed in some circumstances. There are different ways to
+ * handle this, really. This does:
+ * -a / b = a / -b = -(a / b)
+ * -a % b = -(a % b)
+ * a % -b = a % b
+ * which is probably not the best solution, but at least should
+ * have the property that (x/y)*y + (x%y) = x.
+ */
+.align 3
+.globl sfunction
+.ent sfunction
+sfunction:
+ subq $30,STACK,$30
+ .frame $30,STACK,$23
+ .prologue 0
+ bis $24,$25,$28
+ SLONGIFY($28)
+ bge $28,7b
+ stq $24,0($30)
+ subq $31,$24,$28
+ stq $25,8($30)
+ cmovlt $24,$28,$24 /* abs($24) */
+ stq $23,16($30)
+ subq $31,$25,$28
+ stq tmp1,24($30)
+ cmovlt $25,$28,$25 /* abs($25) */
+ unop
+ bsr $23,ufunction
+ ldq $24,0($30)
+ ldq $25,8($30)
+ GETSIGN($28)
+ subq $31,$27,tmp1
+ SLONGIFY($28)
+ ldq $23,16($30)
+ cmovlt $28,tmp1,$27
+ ldq tmp1,24($30)
+ addq $30,STACK,$30
+ ret $31,($23),1
+ .end sfunction
+EXPORT_SYMBOL(sfunction)