From: Björn Töpel <bjorn@xxxxxxxxxxxx>
commit b2d473a6019ef9a54b0156ecdb2e0398c9fa6a24 upstream.
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 <bjorn@xxxxxxxxxxxx>
Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Reviewed-by: Guo Ren <guoren@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230102160748.1307289-1-bjorn@xxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/riscv/kernel/probes/simulate-insn.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- 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);
