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From: Palmer Dabbelt <palmer@dabbelt.com>
To: linux-riscv@lists.infradead.org
Cc: Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	aou@eecs.berkeley.edu, penberg@kernel.org,
	guoren@linux.alibaba.com, me@packi.ch, mhiramat@kernel.org,
	mingo@kernel.org, linux-riscv@lists.infradead.org,
	linux-kernel@vger.kernel.org, kernel-team@android.com,
	Palmer Dabbelt <palmerdabbelt@google.com>,
	kernel test robot <lkp@intel.com>
Subject: [PATCH] RISC-V: probes: Treat the instruction stream as host-endian
Date: Fri, 22 Jan 2021 19:34:29 -0800	[thread overview]
Message-ID: <20210123033429.2072716-1-palmer@dabbelt.com> (raw)

From: Palmer Dabbelt <palmerdabbelt@google.com>

Neither of these are actually correct: the instruction stream is defined
(for versions of the ISA manual newer than 2.2) as a stream of 16-bit
little-endian parcels, which is different than just being little-endian.
In theory we should represent this as a type, but we don't have any
concrete plans for the big endian stuff so it doesn't seem worth the
time -- we've got variants of this all over the place.

Instead I'm just dropping the unnecessary type conversion, which is a
NOP on LE systems but causes an sparse error as the types are all mixed
up.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
 arch/riscv/kernel/probes/decode-insn.c | 2 +-
 arch/riscv/kernel/probes/kprobes.c     | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/kernel/probes/decode-insn.c b/arch/riscv/kernel/probes/decode-insn.c
index 0876c304ca77..0ed043acc882 100644
--- a/arch/riscv/kernel/probes/decode-insn.c
+++ b/arch/riscv/kernel/probes/decode-insn.c
@@ -16,7 +16,7 @@
 enum probe_insn __kprobes
 riscv_probe_decode_insn(probe_opcode_t *addr, struct arch_probe_insn *api)
 {
-	probe_opcode_t insn = le32_to_cpu(*addr);
+	probe_opcode_t insn = *addr;
 
 	/*
 	 * Reject instructions list:
diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c
index e60893bd87db..a2ec18662fee 100644
--- a/arch/riscv/kernel/probes/kprobes.c
+++ b/arch/riscv/kernel/probes/kprobes.c
@@ -57,7 +57,7 @@ int __kprobes arch_prepare_kprobe(struct kprobe *p)
 	}
 
 	/* copy instruction */
-	p->opcode = le32_to_cpu(*p->addr);
+	p->opcode = *p->addr;
 
 	/* decode instruction */
 	switch (riscv_probe_decode_insn(p->addr, &p->ainsn.api)) {
-- 
2.30.0.280.ga3ce27912f-goog


             reply	other threads:[~2021-01-23  3:39 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-23  3:34 Palmer Dabbelt [this message]
2021-01-23  7:33 ` Guo Ren

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