Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
rseq: Allow registering RSEQ with slice extension
Since glibc cares about the number of syscalls required to initialize a new
thread, allow initializing rseq with slice extension on. This avoids having to
do another prctl().
Requested-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260121143207.814193010@infradead.org
+12
-3
+2
-1
include/uapi/linux/rseq.h
+2
-1
include/uapi/linux/rseq.h
+10
-2
kernel/rseq.c
+10
-2
kernel/rseq.c
···
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return 0;
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}
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426
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-
if (unlikely(flags))
427
+
if (unlikely(flags & ~(RSEQ_FLAG_SLICE_EXT_DEFAULT_ON)))
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return -EINVAL;
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if (current->rseq.usrptr) {
···
459
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if (!access_ok(rseq, rseq_len))
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return -EFAULT;
461
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462
-
if (IS_ENABLED(CONFIG_RSEQ_SLICE_EXTENSION))
462
+
if (IS_ENABLED(CONFIG_RSEQ_SLICE_EXTENSION)) {
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rseqfl |= RSEQ_CS_FLAG_SLICE_EXT_AVAILABLE;
464
+
if (rseq_slice_extension_enabled() &&
465
+
(flags & RSEQ_FLAG_SLICE_EXT_DEFAULT_ON))
466
+
rseqfl |= RSEQ_CS_FLAG_SLICE_EXT_ENABLED;
467
+
}
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scoped_user_write_access(rseq, efault) {
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/*
···
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current->rseq.usrptr = rseq;
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current->rseq.len = rseq_len;
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current->rseq.sig = sig;
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+
491
+
#ifdef CONFIG_RSEQ_SLICE_EXTENSION
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+
current->rseq.slice.state.enabled = !!(rseqfl & RSEQ_CS_FLAG_SLICE_EXT_ENABLED);
493
+
#endif
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/*
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* If rseq was previously inactive, and has just been