Commit c56c599d authored by Kristina Martsenko's avatar Kristina Martsenko Committed by Catalin Marinas
Browse files

arm64: probes: Disable kprobes/uprobes on MOPS instructions 



FEAT_MOPS instructions require that all three instructions (prologue,
main and epilogue) appear consecutively in memory. Placing a
kprobe/uprobe on one of them doesn't work as only a single instruction
gets executed out-of-line or simulated. So don't allow placing a probe
on a MOPS instruction.

Fixes: b7564127 ("arm64: mops: detect and enable FEAT_MOPS")
Signed-off-by: default avatarKristina Martsenko <kristina.martsenko@arm.com>
Link: https://lore.kernel.org/r/20240930161051.3777828-2-kristina.martsenko@arm.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 9852d85e

arch/arm64/include/asm/insn.h

+1 −0
Original line number Diff line number Diff line
@@ -353,6 +353,7 @@ __AARCH64_INSN_FUNCS(ldrsw_lit, 0xFF000000, 0x98000000) 
__AARCH64_INSN_FUNCS(exclusive,	0x3F800000, 0x08000000)

__AARCH64_INSN_FUNCS(load_ex,	0x3F400000, 0x08400000)

__AARCH64_INSN_FUNCS(store_ex,	0x3F400000, 0x08000000)

__AARCH64_INSN_FUNCS(mops,	0x3B200C00, 0x19000400)

__AARCH64_INSN_FUNCS(stp,	0x7FC00000, 0x29000000)

__AARCH64_INSN_FUNCS(ldp,	0x7FC00000, 0x29400000)

__AARCH64_INSN_FUNCS(stp_post,	0x7FC00000, 0x28800000)

arch/arm64/kernel/probes/decode-insn.c

+5 −2
Original line number Diff line number Diff line
@@ -58,10 +58,13 @@ static bool __kprobes aarch64_insn_is_steppable(u32 insn) 
	 * Instructions which load PC relative literals are not going to work

	 * when executed from an XOL slot. Instructions doing an exclusive

	 * load/store are not going to complete successfully when single-step

	 * exception handling happens in the middle of the sequence.

	 * exception handling happens in the middle of the sequence. Memory

	 * copy/set instructions require that all three instructions be placed

	 * consecutively in memory.

	 */

	if (aarch64_insn_uses_literal(insn) ||

	    aarch64_insn_is_exclusive(insn))

	    aarch64_insn_is_exclusive(insn) ||

	    aarch64_insn_is_mops(insn))

		return false;



	return true;