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[5.186.118.63]) by smtp.gmail.com with ESMTPSA id i26sm3477986ejc.51.2019.04.09.14.25.50 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 Apr 2019 14:25:50 -0700 (PDT) From: Rasmus Villemoes To: Andrew Morton Cc: Jason Baron , linux-kernel@vger.kernel.org, Rasmus Villemoes , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, Michael Ellerman , Will Deacon , Ingo Molnar Subject: [PATCH 00/10] implement DYNAMIC_DEBUG_RELATIVE_POINTERS Date: Tue, 9 Apr 2019 23:25:07 +0200 Message-Id: <20190409212517.7321-1-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Similar to CONFIG_GENERIC_BUG_RELATIVE_POINTERS that replaces (8 byte) const char* members by (4 byte) signed offsets from the bug_entry, this implements the similar thing for struct _ddebug, the descriptors underlying pr_debug() and friends in a CONFIG_DYNAMIC_DEBUG kernel. Since struct _ddebug has four string members, we save 16 byte per instance. The total savings seem to be comparable to what is saved by an architecture selecting GENERIC_BUG_RELATIVE_POINTERS (see patch 8 for some numbers for a common distro config). While refreshing these patches, which were orignally just targeted at x86-64, it occured to me that despite the implementation relying on inline asm, there's nothing x86 specific about it, and indeed it seems to work out-of-the-box for ppc64 and arm64 as well, but those have only been compile-tested. The first 6 patches are rather pedestrian preparations. The fun stuff is in patch 7, and the remaining three patches are just the minimal boilerplate to hook up the config option and asm-generic header on the three architectures. Rasmus Villemoes (10): linux/device.h: use unique identifier for each struct _ddebug linux/net.h: use unique identifier for each struct _ddebug linux/printk.h: use unique identifier for each struct _ddebug dynamic_debug: introduce accessors for string members of struct _ddebug dynamic_debug: drop use of bitfields in struct _ddebug dynamic_debug: introduce CONFIG_DYNAMIC_DEBUG_RELATIVE_POINTERS dynamic_debug: add asm-generic implementation for DYNAMIC_DEBUG_RELATIVE_POINTERS x86-64: select DYNAMIC_DEBUG_RELATIVE_POINTERS arm64: select DYNAMIC_DEBUG_RELATIVE_POINTERS powerpc: select DYNAMIC_DEBUG_RELATIVE_POINTERS for PPC64 arch/arm64/Kconfig | 1 + arch/arm64/include/asm/Kbuild | 1 + arch/powerpc/Kconfig | 1 + arch/powerpc/include/asm/Kbuild | 1 + arch/x86/Kconfig | 1 + arch/x86/entry/vdso/vdso32/vclock_gettime.c | 1 + arch/x86/include/asm/Kbuild | 1 + include/asm-generic/dynamic_debug.h | 116 ++++++++++++++++++++ include/linux/device.h | 4 +- include/linux/dynamic_debug.h | 26 +++-- include/linux/jump_label.h | 2 + include/linux/net.h | 4 +- include/linux/printk.h | 4 +- lib/Kconfig.debug | 3 + lib/dynamic_debug.c | 111 ++++++++++++++----- 15 files changed, 237 insertions(+), 40 deletions(-) create mode 100644 include/asm-generic/dynamic_debug.h -- 2.20.1