linux-kernel - [PATCH] powerpc/bpf: Enable bpf_probe

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Message-Id: <20200527122844.19524-1-pmladek@suse.com>
Date:   Wed, 27 May 2020 14:28:44 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Miroslav Benes <mbenes@...e.cz>, Petr Mladek <pmladek@...e.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Brendan Gregg <brendan.d.gregg@...il.com>,
        Christoph Hellwig <hch@....de>
Subject: [PATCH] powerpc/bpf: Enable bpf_probe_read{, str}() on powerpc again

The commit 0ebeea8ca8a4d1d453a ("bpf: Restrict bpf_probe_read{, str}() only
to archs where they work") caused that bpf_probe_read{, str}() functions
were not longer available on architectures where the same logical address
might have different content in kernel and user memory mapping. These
architectures should use probe_read_{user,kernel}_str helpers.

For backward compatibility, the problematic functions are still available
on architectures where the user and kernel address spaces are not
overlapping. This is defined CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE.

At the moment, these backward compatible functions are enabled only
on x86_64, arm, and arm64. Let's do it also on powerpc that has
the non overlapping address space as well.

Signed-off-by: Petr Mladek <pmladek@...e.com>
To: Michael Ellerman <mpe@...erman.id.au>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: linuxppc-dev@...ts.ozlabs.org
Cc: linux-kernel@...r.kernel.org
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Brendan Gregg <brendan.d.gregg@...il.com>
Cc: Christoph Hellwig <hch@....de>
---
 arch/powerpc/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d13b5328ca10..b29d7cb38368 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -126,6 +126,7 @@ config PPC
 	select ARCH_HAS_MMIOWB			if PPC64
 	select ARCH_HAS_PHYS_TO_DMA
 	select ARCH_HAS_PMEM_API
+	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
 	select ARCH_HAS_PTE_DEVMAP		if PPC_BOOK3S_64
 	select ARCH_HAS_PTE_SPECIAL
 	select ARCH_HAS_MEMBARRIER_CALLBACKS
-- 
2.26.2