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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-11 08:27:49 +0000
commitace9429bb58fd418f0c81d4c2835699bddf6bde6 (patch)
treeb2d64bc10158fdd5497876388cd68142ca374ed3 /arch/alpha/lib/clear_user.S
parentInitial commit. (diff)
downloadlinux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.tar.xz
linux-ace9429bb58fd418f0c81d4c2835699bddf6bde6.zip
Adding upstream version 6.6.15.upstream/6.6.15
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'arch/alpha/lib/clear_user.S')
-rw-r--r--arch/alpha/lib/clear_user.S102
1 files changed, 102 insertions, 0 deletions
diff --git a/arch/alpha/lib/clear_user.S b/arch/alpha/lib/clear_user.S
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+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * arch/alpha/lib/clear_user.S
+ * Contributed by Richard Henderson <rth@tamu.edu>
+ *
+ * Zero user space, handling exceptions as we go.
+ *
+ * We have to make sure that $0 is always up-to-date and contains the
+ * right "bytes left to zero" value (and that it is updated only _after_
+ * a successful copy). There is also some rather minor exception setup
+ * stuff.
+ */
+#include <linux/export.h>
+
+/* Allow an exception for an insn; exit if we get one. */
+#define EX(x,y...) \
+ 99: x,##y; \
+ .section __ex_table,"a"; \
+ .long 99b - .; \
+ lda $31, $exception-99b($31); \
+ .previous
+
+ .set noat
+ .set noreorder
+ .align 4
+
+ .globl __clear_user
+ .ent __clear_user
+ .frame $30, 0, $26
+ .prologue 0
+
+$loop:
+ and $1, 3, $4 # e0 :
+ beq $4, 1f # .. e1 :
+
+0: EX( stq_u $31, 0($16) ) # e0 : zero one word
+ subq $0, 8, $0 # .. e1 :
+ subq $4, 1, $4 # e0 :
+ addq $16, 8, $16 # .. e1 :
+ bne $4, 0b # e1 :
+ unop # :
+
+1: bic $1, 3, $1 # e0 :
+ beq $1, $tail # .. e1 :
+
+2: EX( stq_u $31, 0($16) ) # e0 : zero four words
+ subq $0, 8, $0 # .. e1 :
+ EX( stq_u $31, 8($16) ) # e0 :
+ subq $0, 8, $0 # .. e1 :
+ EX( stq_u $31, 16($16) ) # e0 :
+ subq $0, 8, $0 # .. e1 :
+ EX( stq_u $31, 24($16) ) # e0 :
+ subq $0, 8, $0 # .. e1 :
+ subq $1, 4, $1 # e0 :
+ addq $16, 32, $16 # .. e1 :
+ bne $1, 2b # e1 :
+
+$tail:
+ bne $2, 1f # e1 : is there a tail to do?
+ ret $31, ($26), 1 # .. e1 :
+
+1: EX( ldq_u $5, 0($16) ) # e0 :
+ clr $0 # .. e1 :
+ nop # e1 :
+ mskqh $5, $0, $5 # e0 :
+ EX( stq_u $5, 0($16) ) # e0 :
+ ret $31, ($26), 1 # .. e1 :
+
+__clear_user:
+ and $17, $17, $0
+ and $16, 7, $4 # e0 : find dest misalignment
+ beq $0, $zerolength # .. e1 :
+ addq $0, $4, $1 # e0 : bias counter
+ and $1, 7, $2 # e1 : number of bytes in tail
+ srl $1, 3, $1 # e0 :
+ beq $4, $loop # .. e1 :
+
+ EX( ldq_u $5, 0($16) ) # e0 : load dst word to mask back in
+ beq $1, $oneword # .. e1 : sub-word store?
+
+ mskql $5, $16, $5 # e0 : take care of misaligned head
+ addq $16, 8, $16 # .. e1 :
+ EX( stq_u $5, -8($16) ) # e0 :
+ addq $0, $4, $0 # .. e1 : bytes left -= 8 - misalignment
+ subq $1, 1, $1 # e0 :
+ subq $0, 8, $0 # .. e1 :
+ br $loop # e1 :
+ unop # :
+
+$oneword:
+ mskql $5, $16, $4 # e0 :
+ mskqh $5, $2, $5 # e0 :
+ or $5, $4, $5 # e1 :
+ EX( stq_u $5, 0($16) ) # e0 :
+ clr $0 # .. e1 :
+
+$zerolength:
+$exception:
+ ret $31, ($26), 1 # .. e1 :
+
+ .end __clear_user
+ EXPORT_SYMBOL(__clear_user)