[PATCH v3 1/1] perf: RISC-V: Limit the number of counters returned from SBI

[PATCH v3 1/1] perf: RISC-V: Limit the number of counters returned from SBI

[Viacheslav Mitrofanov]

Perf gets the number of supported counters from SBI. If it happens that
the number of returned counters more than RISCV_MAX_COUNTERS the code
trusts it. It does not lead to an immediate problem but can potentially
lead to it. Prevent getting more than RISCV_MAX_COUNTERS from SBI.

Signed-off-by: Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
---
Chnages in v3:
- Detail the output

Changes in v2:
- Add new line
- Substitute pr_warn for pr_info

 drivers/perf/riscv_pmu_sbi.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
index 70cb50fd41c2..7bf494930e92 100644
--- a/drivers/perf/riscv_pmu_sbi.c
+++ b/drivers/perf/riscv_pmu_sbi.c
@@ -868,6 +868,12 @@ static int pmu_sbi_device_probe(struct platform_device *pdev)
 		goto out_free;
 	}
 
+	/* It is possible to get from SBI more than max number of counters */
+	if (num_counters > RISCV_MAX_COUNTERS) {
+		num_counters = RISCV_MAX_COUNTERS;
+		pr_info("SBI returned more than maximum number of counters. Limiting the number of counters to %d\n", num_counters);
+	}
+
 	/* cache all the information about counters now */
 	if (pmu_sbi_get_ctrinfo(num_counters, &cmask))
 		goto out_free;
-- 
2.37.2

Re: [PATCH v3 1/1] perf: RISC-V: Limit the number of counters returned from SBI

[Palmer Dabbelt]

On Fri, 05 May 2023 07:20:57 +0000, Viacheslav Mitrofanov wrote:
> Perf gets the number of supported counters from SBI. If it happens that
> the number of returned counters more than RISCV_MAX_COUNTERS the code
> trusts it. It does not lead to an immediate problem but can potentially
> lead to it. Prevent getting more than RISCV_MAX_COUNTERS from SBI.
> 
> 

Applied, thanks!

[1/1] perf: RISC-V: Limit the number of counters returned from SBI
      https://git.kernel.org/palmer/c/ee95b88d71b9

Best regards,
-- 
Palmer Dabbelt <palmer@rivosinc.com>

Re: [PATCH v3 1/1] perf: RISC-V: Limit the number of counters returned from SBI

[patchwork-bot+linux-riscv]

Hello:

This patch was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Fri, 5 May 2023 07:20:57 +0000 you wrote:
> Perf gets the number of supported counters from SBI. If it happens that
> the number of returned counters more than RISCV_MAX_COUNTERS the code
> trusts it. It does not lead to an immediate problem but can potentially
> lead to it. Prevent getting more than RISCV_MAX_COUNTERS from SBI.
> 
> Signed-off-by: Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> Reviewed-by: Atish Patra <atishp@rivosinc.com>
> 
> [...]

Here is the summary with links:
  - [v3,1/1] perf: RISC-V: Limit the number of counters returned from SBI
    https://git.kernel.org/riscv/c/ee95b88d71b9

You are awesome, thank you!
-- 
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