From: "Jose E. Marchesi" <jose.marchesi@oracle.com>
To: binutils@sourceware.org
Subject: [PATCH 4/4] gas: document V3 BPF atomic instructions in the GAS manual
Date: Thu, 11 May 2023 16:13:51 +0200 [thread overview]
Message-ID: <20230511141351.18886-5-jose.marchesi@oracle.com> (raw)
In-Reply-To: <20230511141351.18886-1-jose.marchesi@oracle.com>
gas/ChangeLog:
2023-05-10 Jose E. Marchesi <jose.marchesi@oracle.com>
* doc/c-bpf.texi (BPF Opcodes): Document the V3 BPF atomic
instructions.
---
gas/ChangeLog | 5 +++++
gas/doc/c-bpf.texi | 56 +++++++++++++++++++++++++++++++++++++++++-----
2 files changed, 56 insertions(+), 5 deletions(-)
diff --git a/gas/ChangeLog b/gas/ChangeLog
index a16647bb4a4..987b0c8704f 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,8 @@
+2023-05-10 Jose E. Marchesi <jose.marchesi@oracle.com>
+
+ * doc/c-bpf.texi (BPF Opcodes): Document the V3 BPF atomic
+ instructions.
+
2023-05-10 Jose E. Marchesi <jose.marchesi@oracle.com>
* testsuite/gas/bpf/atomic-v3.s: New file.
diff --git a/gas/doc/c-bpf.texi b/gas/doc/c-bpf.texi
index 0756796adc9..917e0dc1628 100644
--- a/gas/doc/c-bpf.texi
+++ b/gas/doc/c-bpf.texi
@@ -377,14 +377,60 @@ Terminate the eBPF program.
@subsubsection Atomic instructions
-Atomic exchange-and-add instructions are provided in two flavors: one
-for swapping 64-bit quantities and another for 32-bit quantities.
+BPF provides a set of instructions to perform arithmetic and logical
+operations on stored data atomically. These are:
@table @code
-@item xadddw [%d+offset16],%s
-Exchange-and-add a 64-bit value at the specified location.
@item xaddw [%d+offset16],%s
-Exchange-and-add a 32-bit value at the specified location.
+@itemx xadddw [%d+offset16],%s
+Add @code{%s} to the 32 or 64 bit signed integer stored in the
+specified memory location and store the result, atomically.
+@item xorw [%d+offset16],%s
+@itemx xordw [%d+offset16],%s
+Perform a bit-wise or operation between @code{%s} and the 32 or 64 bit
+signed integer stored in the specified memory location and store the
+result, atomically.
+@item xxorw [%d+offset16],%s
+@itemx xxordw [%d+offset16],%s
+Perform a bit-wise xor operation between @code{%s} and the 32 or 64 bit
+signed integer stored in the specified memory location and store the
+result, atomically.
+@end table
+
+@noindent
+Additionally, the following instructions allow to perform arithmetic
+and logical operations on stored data and then fetching the original
+stored value in a register, atomically:
+
+@table @code
+@item xfaddw [%d+offset16],%s
+@itemx xfadddw [%d+offset16],%s
+Add @code{%s} to the 32 or 64 bit signed integer stored in the
+specified memory location, store the result, and set @code{%s} to the
+value originally stored in the memory location, atomically.
+@item xforw [%d+offset16],%s
+@itemx xfordw [%d+offset16],%s
+Perform a bit-wise or operation between @code{%s} and the 32 or 64 bit
+signed integer stored in the specified memory location, store the
+result, and set @code{%s} to the value originally stored in the memory
+location, atomically.
+@item xfxorw [%d+offset16],%s
+@itemx xfxordw [%d+offset16],%s
+Perform a bit-wise xor operation between @code{%s} and the 32 or 64
+bit signed integer stored in the specified memory location, store the
+result, and set @code{%s} to the value originally stored in the memory
+location, atomically.
+@item xchgw [%d+offset16],%s
+@itemx xchgdw [%d+offset16],%s
+Exchange the 32 or 64 bit values in @code{%s} and the specified memory
+location, atomically.
+@item xcmpw [%d+offset16],%s
+@itemx xcmpdw [%d+offset16],%s
+Compare and exchange operation. Compare the 32 or 64 bit value stored
+in the specified memory location to the contents of the @code{%r0}
+register. If they are equal, store @code{%s} in the memory location.
+In any case, update @code{%r0} with the original contents of the
+memory location.
@end table
@node BPF Pseudo-C Syntax
--
2.30.2
prev parent reply other threads:[~2023-05-11 14:14 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-11 14:13 [PATCH 0/4] Add support for V3 BPF atomic instructions Jose E. Marchesi
2023-05-11 14:13 ` [PATCH 1/4] opcodes: use CGEN_INSN_LGUINT for base instructions Jose E. Marchesi
2023-05-11 16:05 ` Jan Beulich
2023-05-17 13:03 ` Nick Clifton
2023-05-17 14:03 ` Jose E. Marchesi
2023-07-21 22:34 ` David Faust
2023-07-22 6:53 ` Jose E. Marchesi
2023-05-11 14:13 ` [PATCH 2/4] cpu: add V3 BPF atomic instructions Jose E. Marchesi
2023-05-11 14:13 ` [PATCH 3/4] gas: add tests for BPF V3 " Jose E. Marchesi
2023-05-11 14:13 ` Jose E. Marchesi [this message]
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