diff options
| author | Atish Patra <[email protected]> | 2025-05-13 17:25:15 -0700 |
|---|---|---|
| committer | Anup Patel <[email protected]> | 2025-07-21 16:33:03 +0530 |
| commit | 5b305e30a55d93d507006dd11685bdeb7e7207e8 (patch) | |
| tree | 75d41afc273af88b80659378ca93dbc2f81bf01d | |
| parent | 663b05a5f745f6b1360f073587bb57fe9af6a40a (diff) | |
lib: sbi: Only enable TM bit in scounteren
The S-mode should disable Cycle and instruction counter for user space
to avoid side channel attacks. The Linux kernel already does this so that
any random user space code shouldn't be able to monitor cycle/instruction
without higher privilege mode involvement.
Remove the CY/IR bits in scountern in OpenSBI.
Reviewed-by: Anup Patel <[email protected]>
Signed-off-by: Atish Patra <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Anup Patel <[email protected]>
| -rw-r--r-- | lib/sbi/sbi_hart.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/lib/sbi/sbi_hart.c b/lib/sbi/sbi_hart.c index 054a405c..6a2d7d6f 100644 --- a/lib/sbi/sbi_hart.c +++ b/lib/sbi/sbi_hart.c @@ -49,10 +49,10 @@ static void mstatus_init(struct sbi_scratch *scratch) csr_write(CSR_MSTATUS, mstatus_val); - /* Disable user mode usage of all perf counters except default ones (CY, TM, IR) */ + /* Disable user mode usage of all perf counters except TM */ if (misa_extension('S') && sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_10) - csr_write(CSR_SCOUNTEREN, 7); + csr_write(CSR_SCOUNTEREN, 0x02); /** * OpenSBI doesn't use any PMU counters in M-mode. |