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Message-Id: <4fd69ef7945518c3e27f96b95046a5c1468d35bf.1675245773.git.christophe.leroy@csgroup.eu>
Date: Wed, 1 Feb 2023 11:04:23 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Michael Ellerman <mpe@...erman.id.au>,
Nicholas Piggin <npiggin@...il.com>,
"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
bpf@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Andrii Nakryiko <andrii@...nel.org>,
Martin KaFai Lau <martin.lau@...ux.dev>,
Song Liu <song@...nel.org>, Yonghong Song <yhs@...com>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>,
Stanislav Fomichev <sdf@...gle.com>,
Hao Luo <haoluo@...gle.com>, Jiri Olsa <jolsa@...nel.org>
Subject: [PATCH v2 1/9] powerpc: Remove __kernel_text_address() in show_instructions()
That test was introducted in 2006 by
commit 00ae36de49cc ("[POWERPC] Better check in show_instructions").
At that time, there was no BPF progs.
As seen in message of commit 89d21e259a94 ("powerpc/bpf/32: Fix Oops
on tail call tests"), when a page fault occurs in test_bpf.ko for
instance, the code is dumped as XXXXXXXXs. Allthough
__kernel_text_address() checks is_bpf_text_address(), it seems it is
not enough.
Today, show_instructions() uses get_kernel_nofault() to read the code,
so there is no real need for additional verifications.
ARM64 and x86 don't do any additional check before dumping
instructions. Do the same and remove __kernel_text_address()
in show_instructions().
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
arch/powerpc/kernel/process.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index c22cc234672f..effe9697905d 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -1405,8 +1405,7 @@ static void show_instructions(struct pt_regs *regs)
for (i = 0; i < NR_INSN_TO_PRINT; i++) {
int instr;
- if (!__kernel_text_address(pc) ||
- get_kernel_nofault(instr, (const void *)pc)) {
+ if (get_kernel_nofault(instr, (const void *)pc)) {
pr_cont("XXXXXXXX ");
} else {
if (nip == pc)
--
2.39.1
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