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authorAmit Daniel Kachhap <amit.kachhap@arm.com>2020-09-14 14:06:56 +0530
committerWill Deacon <will@kernel.org>2020-09-14 12:07:03 +0100
commit03c9c8fad6cb5e8fdfb40287fa1cdf8ee2db0b67 (patch)
tree28016ad28f6ae4f16e8a63da88513080811f4950
parentarm64: kprobe: disable probe of fault prone ptrauth instruction (diff)
downloadlinux-dev-03c9c8fad6cb5e8fdfb40287fa1cdf8ee2db0b67.tar.xz
linux-dev-03c9c8fad6cb5e8fdfb40287fa1cdf8ee2db0b67.zip
arm64: kprobe: clarify the comment of steppable hint instructions
The existing comment about steppable hint instruction is not complete and only describes NOP instructions as steppable. As the function aarch64_insn_is_steppable_hint allows all white-listed instruction to be probed so the comment is updated to reflect this. Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com> Reviewed-by: Dave Martin <dave.martin@arm.com> Link: https://lore.kernel.org/r/20200914083656.21428-7-amit.kachhap@arm.com Signed-off-by: Will Deacon <will@kernel.org>
-rw-r--r--arch/arm64/kernel/probes/decode-insn.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/arch/arm64/kernel/probes/decode-insn.c b/arch/arm64/kernel/probes/decode-insn.c
index c541fb48886e..104101f633b1 100644
--- a/arch/arm64/kernel/probes/decode-insn.c
+++ b/arch/arm64/kernel/probes/decode-insn.c
@@ -43,8 +43,10 @@ static bool __kprobes aarch64_insn_is_steppable(u32 insn)
!= AARCH64_INSN_SPCLREG_DAIF;
/*
- * The HINT instruction is is problematic when single-stepping,
- * except for the NOP case.
+ * The HINT instruction is steppable only if it is in whitelist
+ * and the rest of other such instructions are blocked for
+ * single stepping as they may cause exception or other
+ * unintended behaviour.
*/
if (aarch64_insn_is_hint(insn))
return aarch64_insn_is_steppable_hint(insn);