OrgACRN
/
acrn-kernel
mirror of https://github.com/projectacrn/acrn-kernel.git
1
0
Fork 0
Code Issues Releases Wiki Activity

riscv, kprobes: Stricter c.jr/c.jalr decoding 

commit b2d473a601 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: c22b0bcb1d ("riscv: Add kprobes supported")
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230102160748.1307289-1-bjorn@kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Björn Töpel 2023-01-02 17:07:48 +01:00 committed by Greg Kroah-Hartman
parent 36fd385ae2
commit a33220faea
1 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/riscv/kernel/probes/simulate-insn.h
View File

@ -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);