This allows reducing the size of struct _ddebug from 56 to 40 bytes. There's one such struct for each pr_debug(), netdev_debug() etc. in a CONFIG_DYNAMIC_DEBUG kernel. An Ubuntu 4.15 kernel has about 2550 entries in the __verbose section of vmlinux, amounting to ~40K saved. (Modules also become smaller, but it's harder to quantify how much that yields at runtime.)
For comparison, the __bug_table section of that Ubuntu kernel is 75576 bytes, i.e. 6298 12-byte bug_entrys, so GENERIC_BUG_RELATIVE_POINTERS saves ~50K. Due to the build-time sanity checks in asm-generic/dynamic_debug.h, we need to add another #undef to vclock_gettime.c. Signed-off-by: Rasmus Villemoes <[email protected]> --- arch/x86/Kconfig | 1 + arch/x86/entry/vdso/vdso32/vclock_gettime.c | 1 + arch/x86/include/asm/Kbuild | 1 + 3 files changed, 3 insertions(+) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 2bbbd4d1ba31..ed44ea2b9556 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -30,6 +30,7 @@ config X86_64 select NEED_DMA_MAP_STATE select SWIOTLB select ARCH_HAS_SYSCALL_WRAPPER + select HAVE_DYNAMIC_DEBUG_RELATIVE_POINTERS config FORCE_DYNAMIC_FTRACE def_bool y diff --git a/arch/x86/entry/vdso/vdso32/vclock_gettime.c b/arch/x86/entry/vdso/vdso32/vclock_gettime.c index 9242b28418d5..9acec4426206 100644 --- a/arch/x86/entry/vdso/vdso32/vclock_gettime.c +++ b/arch/x86/entry/vdso/vdso32/vclock_gettime.c @@ -17,6 +17,7 @@ #undef CONFIG_ILLEGAL_POINTER_VALUE #undef CONFIG_SPARSEMEM_VMEMMAP #undef CONFIG_NR_CPUS +#undef CONFIG_DYNAMIC_DEBUG_RELATIVE_POINTERS #define CONFIG_X86_32 1 #define CONFIG_PGTABLE_LEVELS 2 diff --git a/arch/x86/include/asm/Kbuild b/arch/x86/include/asm/Kbuild index 8b52bc5ddf69..3b630b4d37d7 100644 --- a/arch/x86/include/asm/Kbuild +++ b/arch/x86/include/asm/Kbuild @@ -8,6 +8,7 @@ generated-y += unistd_64_x32.h generated-y += xen-hypercalls.h generic-y += dma-contiguous.h +generic-y += dynamic_debug.h generic-y += early_ioremap.h generic-y += export.h generic-y += mcs_spinlock.h -- 2.20.1
