From ab7fa6b05ebbe2a8cc07114014f14fd2326fb80a Mon Sep 17 00:00:00 2001 From: Jisheng Zhang Date: Wed, 24 May 2023 00:54:59 +0800 Subject: [PATCH 1/5] riscv: move options to keep entries sorted Recently, some commits break the entries order. Properly move their locations to keep entries sorted. Signed-off-by: Jisheng Zhang Reviewed-by: Conor Dooley Acked-by: Guo Ren Tested-by: Nick Desaulniers # build Link: https://lore.kernel.org/r/20230523165502.2592-2-jszhang@kernel.org Signed-off-by: Palmer Dabbelt --- arch/riscv/Kconfig | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 348c0fa1fc8c..8f55aa4aae34 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -101,6 +101,11 @@ config RISCV select HAVE_CONTEXT_TRACKING_USER select HAVE_DEBUG_KMEMLEAK select HAVE_DMA_CONTIGUOUS if MMU + select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE) + select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE + select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL + select HAVE_FUNCTION_GRAPH_TRACER + select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION select HAVE_EBPF_JIT if MMU select HAVE_FUNCTION_ARG_ACCESS_API select HAVE_FUNCTION_ERROR_INJECTION @@ -110,7 +115,6 @@ config RISCV select HAVE_KPROBES if !XIP_KERNEL select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL select HAVE_KRETPROBES if !XIP_KERNEL - select HAVE_RETHOOK if !XIP_KERNEL select HAVE_MOVE_PMD select HAVE_MOVE_PUD select HAVE_PCI @@ -119,6 +123,7 @@ config RISCV select HAVE_PERF_USER_STACK_DUMP select HAVE_POSIX_CPU_TIMERS_TASK_WORK select HAVE_REGS_AND_STACK_ACCESS_API + select HAVE_RETHOOK if !XIP_KERNEL select HAVE_RSEQ select HAVE_STACKPROTECTOR select HAVE_SYSCALL_TRACEPOINTS @@ -142,11 +147,6 @@ config RISCV select TRACE_IRQFLAGS_SUPPORT select UACCESS_MEMCPY if !MMU select ZONE_DMA32 if 64BIT - select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && MMU && (CLANG_SUPPORTS_DYNAMIC_FTRACE || GCC_SUPPORTS_DYNAMIC_FTRACE) - select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE - select HAVE_FTRACE_MCOUNT_RECORD if !XIP_KERNEL - select HAVE_FUNCTION_GRAPH_TRACER - select HAVE_FUNCTION_TRACER if !XIP_KERNEL && !PREEMPTION config CLANG_SUPPORTS_DYNAMIC_FTRACE def_bool CC_IS_CLANG From cead443a306262a16056d84d63b5a6a10908eb62 Mon Sep 17 00:00:00 2001 From: Jisheng Zhang Date: Wed, 24 May 2023 00:55:00 +0800 Subject: [PATCH 2/5] riscv: vmlinux-xip.lds.S: remove .alternative section ALTERNATIVE mechanism can't work on XIP, and this is also reflected by below Kconfig dependency: RISCV_ALTERNATIVE ... depends on !XIP_KERNEL ... So there's no .alternative section at all for XIP case, remove it. Signed-off-by: Jisheng Zhang Reviewed-by: Conor Dooley Reviewed-by: Guo Ren Tested-by: Nick Desaulniers # build Link: https://lore.kernel.org/r/20230523165502.2592-3-jszhang@kernel.org Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/vmlinux-xip.lds.S | 6 ------ 1 file changed, 6 deletions(-) diff --git a/arch/riscv/kernel/vmlinux-xip.lds.S b/arch/riscv/kernel/vmlinux-xip.lds.S index eab9edc3b631..50767647fbc6 100644 --- a/arch/riscv/kernel/vmlinux-xip.lds.S +++ b/arch/riscv/kernel/vmlinux-xip.lds.S @@ -98,12 +98,6 @@ SECTIONS __soc_builtin_dtb_table_end = .; } - . = ALIGN(8); - .alternative : { - __alt_start = .; - *(.alternative) - __alt_end = .; - } __init_end = .; . = ALIGN(16); From d4035ff16bfa73915f74cb3d28f878aff1da510a Mon Sep 17 00:00:00 2001 From: Jisheng Zhang Date: Wed, 24 May 2023 00:55:01 +0800 Subject: [PATCH 3/5] vmlinux.lds.h: use correct .init.data.* section name If building with -fdata-sections on riscv, LD_ORPHAN_WARN will warn similar as below: riscv64-linux-gnu-ld: warning: orphan section `.init.data.efi_loglevel' from `./drivers/firmware/efi/libstub/printk.stub.o' being placed in section `.init.data.efi_loglevel' I believe this is caused by a a typo: init.data.* should be .init.data.* Signed-off-by: Jisheng Zhang Reviewed-by: Kefeng Wang Tested-by: Nick Desaulniers # build Link: https://lore.kernel.org/r/20230523165502.2592-4-jszhang@kernel.org Signed-off-by: Palmer Dabbelt --- include/asm-generic/vmlinux.lds.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index d1f57e4868ed..371026ca7221 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -688,7 +688,7 @@ /* init and exit section handling */ #define INIT_DATA \ KEEP(*(SORT(___kentry+*))) \ - *(.init.data init.data.*) \ + *(.init.data .init.data.*) \ MEM_DISCARD(init.data*) \ KERNEL_CTORS() \ MCOUNT_REC() \ From c828856b51bb4180c0803c12ffaeb86c41336c11 Mon Sep 17 00:00:00 2001 From: Zhangjin Wu Date: Wed, 24 May 2023 00:55:02 +0800 Subject: [PATCH 4/5] riscv: enable HAVE_LD_DEAD_CODE_DATA_ELIMINATION Select CONFIG_HAVE_LD_DEAD_CODE_DATA_ELIMINATION for RISC-V, allowing the user to enable dead code elimination. In order for this to work, ensure that we keep the alternative table by annotating them with KEEP. This boots well on qemu with both rv32_defconfig & rv64 defconfig, but it only shrinks their builds by ~1%, a smaller config is thereforce customized to test this feature: | rv32 | rv64 --------|------------------------|--------------------- No DCE | 4460684 | 4893488 DCE | 3986716 | 4376400 Shrink | 473968 (~10.6%) | 517088 (~10.5%) The config used above only reserves necessary options to boot on qemu with serial console, more like the size-critical embedded scenes: - rv64 config: https://pastebin.com/crz82T0s - rv32 config: rv64 config + 32-bit.config Here is Jisheng's original commit-msg: When trying to run linux with various opensource riscv core on resource limited FPGA platforms, for example, those FPGAs with less than 16MB SDRAM, I want to save mem as much as possible. One of the major technologies is kernel size optimizations, I found that riscv does not currently support HAVE_LD_DEAD_CODE_DATA_ELIMINATION, which passes -fdata-sections, -ffunction-sections to CFLAGS and passes the --gc-sections flag to the linker. This not only benefits my case on FPGA but also benefits defconfigs. Here are some notable improvements from enabling this with defconfigs: nommu_k210_defconfig: text data bss dec hex 1112009 410288 59837 1582134 182436 before 962838 376656 51285 1390779 1538bb after rv32_defconfig: text data bss dec hex 8804455 2816544 290577 11911576 b5c198 before 8692295 2779872 288977 11761144 b375f8 after defconfig: text data bss dec hex 9438267 3391332 485333 13314932 cb2b74 before 9285914 3350052 483349 13119315 c82f53 after Signed-off-by: Zhangjin Wu Co-developed-by: Jisheng Zhang Signed-off-by: Jisheng Zhang Reviewed-by: Guo Ren Tested-by: Bin Meng Reviewed-by: Kefeng Wang Tested-by: Nick Desaulniers # build Link: https://lore.kernel.org/r/20230523165502.2592-5-jszhang@kernel.org Signed-off-by: Palmer Dabbelt --- arch/riscv/Kconfig | 1 + arch/riscv/kernel/vmlinux.lds.S | 6 +++--- 2 files changed, 4 insertions(+), 3 deletions(-) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 8f55aa4aae34..62e84fee2cfd 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -115,6 +115,7 @@ config RISCV select HAVE_KPROBES if !XIP_KERNEL select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL select HAVE_KRETPROBES if !XIP_KERNEL + select HAVE_LD_DEAD_CODE_DATA_ELIMINATION select HAVE_MOVE_PMD select HAVE_MOVE_PUD select HAVE_PCI diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S index e5f9f4677bbf..492dd4b8f3d6 100644 --- a/arch/riscv/kernel/vmlinux.lds.S +++ b/arch/riscv/kernel/vmlinux.lds.S @@ -85,11 +85,11 @@ SECTIONS INIT_DATA_SECTION(16) .init.pi : { - *(.init.pi*) + KEEP(*(.init.pi*)) } .init.bss : { - *(.init.bss) /* from the EFI stub */ + KEEP(*(.init.bss*)) /* from the EFI stub */ } .exit.data : { @@ -112,7 +112,7 @@ SECTIONS . = ALIGN(8); .alternative : { __alt_start = .; - *(.alternative) + KEEP(*(.alternative)) __alt_end = .; } __init_end = .; From f7584322e4fef794b290e5fdb290fa92a925236e Mon Sep 17 00:00:00 2001 From: Nick Desaulniers Date: Fri, 23 Jun 2023 10:06:17 -0700 Subject: [PATCH 5/5] riscv: disable HAVE_LD_DEAD_CODE_DATA_ELIMINATION for LLD Linking allyesconfig with ld.lld-17 with CONFIG_DEAD_CODE_ELIMINATION=y takes hours. Assuming this is a performance regression that can be fixed, tentatively disable this for now so that allyesconfig builds don't start timing out. If and when there's a fix to ld.lld, this can be converted to a version check instead so that users of older but still supported versions of ld.lld don't hurt themselves by enabling CONFIG_LD_DEAD_CODE_DATA_ELIMINATION=y. Link: https://github.com/ClangBuiltLinux/linux/issues/1881 Link: https://lore.kernel.org/linux-riscv/ZJXTwqZIkXLxXaSi@google.com/ Reported-by: Palmer Dabbelt Suggested-by: Nathan Chancellor Signed-off-by: Nick Desaulniers Signed-off-by: Palmer Dabbelt --- arch/riscv/Kconfig | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 62e84fee2cfd..a8a9387eb284 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -115,7 +115,8 @@ config RISCV select HAVE_KPROBES if !XIP_KERNEL select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL select HAVE_KRETPROBES if !XIP_KERNEL - select HAVE_LD_DEAD_CODE_DATA_ELIMINATION + # https://github.com/ClangBuiltLinux/linux/issues/1881 + select HAVE_LD_DEAD_CODE_DATA_ELIMINATION if !LD_IS_LLD select HAVE_MOVE_PMD select HAVE_MOVE_PUD select HAVE_PCI