From b2d473a6019ef9a54b0156ecdb2e0398c9fa6a24 Mon Sep 17 00:00:00 2001 From: Björn Töpel Date: Mon, 2 Jan 2023 17:07:48 +0100 Subject: riscv, kprobes: Stricter c.jr/c.jalr decoding MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In the compressed instruction extension, c.jr, c.jalr, c.mv, and c.add is encoded the following way (each instruction is 16b): ---+-+-----------+-----------+-- 100 0 rs1[4:0]!=0 00000 10 : c.jr 100 1 rs1[4:0]!=0 00000 10 : c.jalr 100 0 rd[4:0]!=0 rs2[4:0]!=0 10 : c.mv 100 1 rd[4:0]!=0 rs2[4:0]!=0 10 : c.add The following logic is used to decode c.jr and c.jalr: insn & 0xf007 == 0x8002 => instruction is an c.jr insn & 0xf007 == 0x9002 => instruction is an c.jalr When 0xf007 is used to mask the instruction, c.mv can be incorrectly decoded as c.jr, and c.add as c.jalr. Correct the decoding by changing the mask from 0xf007 to 0xf07f. Fixes: c22b0bcb1dd0 ("riscv: Add kprobes supported") Signed-off-by: Björn Töpel Reviewed-by: Conor Dooley Reviewed-by: Guo Ren Link: https://lore.kernel.org/r/20230102160748.1307289-1-bjorn@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/probes/simulate-insn.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/riscv') diff --git a/arch/riscv/kernel/probes/simulate-insn.h b/arch/riscv/kernel/probes/simulate-insn.h index cb6ff7dccb92..de8474146a9b 100644 --- a/arch/riscv/kernel/probes/simulate-insn.h +++ b/arch/riscv/kernel/probes/simulate-insn.h @@ -31,9 +31,9 @@ __RISCV_INSN_FUNCS(fence, 0x7f, 0x0f); } while (0) __RISCV_INSN_FUNCS(c_j, 0xe003, 0xa001); -__RISCV_INSN_FUNCS(c_jr, 0xf007, 0x8002); +__RISCV_INSN_FUNCS(c_jr, 0xf07f, 0x8002); __RISCV_INSN_FUNCS(c_jal, 0xe003, 0x2001); -__RISCV_INSN_FUNCS(c_jalr, 0xf007, 0x9002); +__RISCV_INSN_FUNCS(c_jalr, 0xf07f, 0x9002); __RISCV_INSN_FUNCS(c_beqz, 0xe003, 0xc001); __RISCV_INSN_FUNCS(c_bnez, 0xe003, 0xe001); __RISCV_INSN_FUNCS(c_ebreak, 0xffff, 0x9002); -- cgit v1.2.3