| Message ID | 20240325203755.1811-2-jarkko@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v3,1/2] kprobes: textmem API | expand |
On Mon Mar 25, 2024 at 10:37 PM EET, Jarkko Sakkinen wrote: > Tacing with kprobes while running a monolithic kernel is currently > impossible due the kernel module allocator dependency. > > Address the issue by implementing textmem API for RISC-V. > > Link: https://www.sochub.fi # for power on testing new SoC's with a minimal stack > Link: https://lore.kernel.org/all/20220608000014.3054333-1-jarkko@profian.com/ # continuation > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> I think that for any use case it is best for overall good to realize it like this. I.e. only create patch sets related to the topic that change behavior for arch's that are in your heavy use. For me that mean x86 and RISC-V. That is why I shrinked this from to focus into more narrow scope. For microarch's more alien to one, it is just too easy to make sloppy mistakes, which could cause unwanted harm. E.g. it is for best of arch/sh that someone involved with that microarchitecture does later on the shenanigans. BR, Jarkko
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index e3142ce531a0..499512fb17ff 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -132,6 +132,7 @@ config RISCV select HAVE_KPROBES if !XIP_KERNEL select HAVE_KPROBES_ON_FTRACE if !XIP_KERNEL select HAVE_KRETPROBES if !XIP_KERNEL + select HAVE_ALLOC_EXECMEM if !XIP_KERNEL # https://github.com/ClangBuiltLinux/linux/issues/1881 select HAVE_LD_DEAD_CODE_DATA_ELIMINATION if !LD_IS_LLD select HAVE_MOVE_PMD diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile index 604d6bf7e476..337797f10d3e 100644 --- a/arch/riscv/kernel/Makefile +++ b/arch/riscv/kernel/Makefile @@ -73,6 +73,9 @@ obj-$(CONFIG_SMP) += cpu_ops.o obj-$(CONFIG_RISCV_BOOT_SPINWAIT) += cpu_ops_spinwait.o obj-$(CONFIG_MODULES) += module.o +ifeq ($(CONFIG_ALLOC_EXECMEM),y) +obj-y += execmem.o +endif obj-$(CONFIG_MODULE_SECTIONS) += module-sections.o obj-$(CONFIG_CPU_PM) += suspend_entry.o suspend.o diff --git a/arch/riscv/kernel/execmem.c b/arch/riscv/kernel/execmem.c new file mode 100644 index 000000000000..4191251476d0 --- /dev/null +++ b/arch/riscv/kernel/execmem.c @@ -0,0 +1,22 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +#include <linux/mm.h> +#include <linux/moduleloader.h> +#include <linux/vmalloc.h> +#include <asm/sections.h> + +void *alloc_execmem(unsigned long size, gfp_t /* gfp */) +{ + return __vmalloc_node_range(size, 1, MODULES_VADDR, + MODULES_END, GFP_KERNEL, + PAGE_KERNEL, 0, NUMA_NO_NODE, + __builtin_return_address(0)); +} + +void free_execmem(void *region) +{ + if (in_interrupt()) + pr_warn("In interrupt context: vmalloc may not work.\n"); + + vfree(region); +} diff --git a/kernel/kprobes.c b/kernel/kprobes.c index a1a547723c3c..87fd8c14a938 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -119,7 +119,7 @@ void __weak *alloc_insn_page(void) * for most of the architectures. * (e.g. x86-64 needs this to handle the %rip-relative fixups.) */ - return alloc_execmem(PAGE_SIZE); + return alloc_execmem(PAGE_SIZE, GFP_KERNEL); } static void free_insn_page(void *page)
Tacing with kprobes while running a monolithic kernel is currently impossible due the kernel module allocator dependency. Address the issue by implementing textmem API for RISC-V. Link: https://www.sochub.fi # for power on testing new SoC's with a minimal stack Link: https://lore.kernel.org/all/20220608000014.3054333-1-jarkko@profian.com/ # continuation Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> --- v3: - Architecture independent parts have been split to separate patches. - Do not change arch/riscv/kernel/module.c as it is out of scope for this patch set now. v2: - Better late than never right? :-) - Focus only to RISC-V for now to make the patch more digestable. This is the arch where I use the patch on a daily basis to help with QA. - Introduce HAVE_KPROBES_ALLOC flag to help with more gradual migration. --- arch/riscv/Kconfig | 1 + arch/riscv/kernel/Makefile | 3 +++ arch/riscv/kernel/execmem.c | 22 ++++++++++++++++++++++ kernel/kprobes.c | 2 +- 4 files changed, 27 insertions(+), 1 deletion(-) create mode 100644 arch/riscv/kernel/execmem.c