From 71a5b3db9f209ea5d1e07371017e65398d3c6fbc Mon Sep 17 00:00:00 2001 From: Jordan Niethe Date: Wed, 9 Jun 2021 11:34:24 +1000 Subject: [PATCH] powerpc/lib/code-patching: Set up Strict RWX patching earlier setup_text_poke_area() is a late init call so it runs before mark_rodata_ro() and after the init calls. This lets all the init code patching simply write to their locations. In the future, kprobes is going to allocate its instruction pages RO which means they will need setup_text__poke_area() to have been already called for their code patching. However, init_kprobes() (which allocates and patches some instruction pages) is an early init call so it happens before setup_text__poke_area(). start_kernel() calls poking_init() before any of the init calls. On powerpc, poking_init() is currently a nop. setup_text_poke_area() relies on kernel virtual memory, cpu hotplug and per_cpu_areas being setup. setup_per_cpu_areas(), boot_cpu_hotplug_init() and mm_init() are called before poking_init(). Turn setup_text_poke_area() into poking_init(). Signed-off-by: Jordan Niethe Reviewed-by: Christophe Leroy Reviewed-by: Russell Currey [mpe: Fold in missing prototype for poking_init() from lkp] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210609013431.9805-3-jniethe5@gmail.com --- arch/powerpc/include/asm/pgtable.h | 1 + arch/powerpc/lib/code-patching.c | 14 ++++---------- 2 files changed, 5 insertions(+), 10 deletions(-) diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h index b9c8641654f43..b1e6c9ee32060 100644 --- a/arch/powerpc/include/asm/pgtable.h +++ b/arch/powerpc/include/asm/pgtable.h @@ -76,6 +76,7 @@ extern unsigned long empty_zero_page[]; extern pgd_t swapper_pg_dir[]; extern void paging_init(void); +void poking_init(void); extern unsigned long ioremap_bot; diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index b2d6923767696..f9a3019e37b43 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -69,22 +69,16 @@ static int text_area_cpu_down(unsigned int cpu) } /* - * Run as a late init call. This allows all the boot time patching to be done - * simply by patching the code, and then we're called here prior to - * mark_rodata_ro(), which happens after all init calls are run. Although - * BUG_ON() is rude, in this case it should only happen if ENOMEM, and we judge - * it as being preferable to a kernel that will crash later when someone tries - * to use patch_instruction(). + * Although BUG_ON() is rude, in this case it should only happen if ENOMEM, and + * we judge it as being preferable to a kernel that will crash later when + * someone tries to use patch_instruction(). */ -static int __init setup_text_poke_area(void) +void __init poking_init(void) { BUG_ON(!cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "powerpc/text_poke:online", text_area_cpu_up, text_area_cpu_down)); - - return 0; } -late_initcall(setup_text_poke_area); /* * This can be called for kernel text or a module.