2023-07-26 06:47:51

by Chenguang Zhao

Subject: [PATCH] LoongArch: eBPF: Restrict bpf_probe_read{, str}() only to archs where they work

When we run nettrace on LoongArch, there is a problem that
ERROR: failed to load kprobe-based eBPF
ERROR: failed to load kprobe-based bpf

Because ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE dose not exist,
so we enable it.

The patch reference upstream id 0ebeea8ca8a4d1d453ad299aef0507dab04f6e8d.

Signed-off-by: zhaochenguang <[email protected]>
---
arch/loongarch/Kconfig | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 903096bd87f8..4a156875e9cc 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -11,6 +11,7 @@ config LOONGARCH
select ARCH_ENABLE_MEMORY_HOTREMOVE
select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
select ARCH_HAS_PTE_SPECIAL
+ select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_INLINE_READ_LOCK if !PREEMPTION
select ARCH_INLINE_READ_LOCK_BH if !PREEMPTION
--
2.25.1

2023-07-26 08:50:35

by WANG Xuerui

Subject: Re: [PATCH] LoongArch: eBPF: Restrict bpf_probe_read{, str}() only to archs where they work

On 2023/7/26 14:29, zhaochenguang wrote:
> When we run nettrace on LoongArch, there is a problem that
> ERROR: failed to load kprobe-based eBPF
> ERROR: failed to load kprobe-based bpf
>
> Because ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE dose not exist,
> so we enable it.
>
> The patch reference upstream id 0ebeea8ca8a4d1d453ad299aef0507dab04f6e8d.

The description is a bit hard to follow. Rephrasing a bit:

"Currently nettrace does not work on LoongArch due to missing
bpf_probe_read{,str}() support, with the error message:

ERROR: failed to load kprobe-based eBPF
ERROR: failed to load kprobe-based bpf

According to commit 0ebeea8ca8a4d ("bpf: Restrict bpf_probe_read{,
str}() only to archs where they work"), we only need to select
CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE to add said support,
because LoongArch does have non-overlapping address ranges for kernel
and userspace."

Also, the patch subject does not make sense. Looking at precedents such
as commit 66633abd0642f ("MIPS/bpf: Enable bpf_probe_read{, str}() on
MIPS again") and commit d195b1d1d1196 ("powerpc/bpf: Enable
bpf_probe_read{, str}() on powerpc again"), we can instead re-title the
commit as "LoongArch/bpf: Enable bpf_probe_read{, str}() on LoongArch".
(No "again" because commit 0ebeea8ca8a4d actually predated the LoongArch
port.)

>
> Signed-off-by: zhaochenguang <[email protected]>
> ---
> arch/loongarch/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 903096bd87f8..4a156875e9cc 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -11,6 +11,7 @@ config LOONGARCH
> select ARCH_ENABLE_MEMORY_HOTREMOVE
> select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
> select ARCH_HAS_PTE_SPECIAL
> + select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE

Please keep the list in alphabetical order by moving this one line above.

> select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
> select ARCH_INLINE_READ_LOCK if !PREEMPTION
> select ARCH_INLINE_READ_LOCK_BH if !PREEMPTION

--
WANG "xen0n" Xuerui

Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/

2023-07-27 01:51:24

by Huacai Chen

Subject: Re: [PATCH] LoongArch: eBPF: Restrict bpf_probe_read{, str}() only to archs where they work

Hi,

Usually, your E-mail format should be
Chenguang Zhao <[email protected]>

Huacai

On Wed, Jul 26, 2023 at 2:29 PM zhaochenguang <[email protected]> wrote:
>
> When we run nettrace on LoongArch, there is a problem that
> ERROR: failed to load kprobe-based eBPF
> ERROR: failed to load kprobe-based bpf
>
> Because ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE dose not exist,
> so we enable it.
>
> The patch reference upstream id 0ebeea8ca8a4d1d453ad299aef0507dab04f6e8d.
>
> Signed-off-by: zhaochenguang <[email protected]>
> ---
> arch/loongarch/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
> index 903096bd87f8..4a156875e9cc 100644
> --- a/arch/loongarch/Kconfig
> +++ b/arch/loongarch/Kconfig
> @@ -11,6 +11,7 @@ config LOONGARCH
> select ARCH_ENABLE_MEMORY_HOTREMOVE
> select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
> select ARCH_HAS_PTE_SPECIAL
> + select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
> select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
> select ARCH_INLINE_READ_LOCK if !PREEMPTION
> select ARCH_INLINE_READ_LOCK_BH if !PREEMPTION
> --
> 2.25.1
>
>