Re: powerpc: Ensure .mem(init|exit).text are within _stext/_etext
On Thu, 2016-15-09 at 05:11:59 UTC, Michael Ellerman wrote: > In our linker script we open code the list of text sections, because we > need to include the __ftr_alt sections, which are arch-specific. > > This means we can't use TEXT_TEXT as defined in vmlinux.lds.h, and so we > don't have the MEM_KEEP() logic for memory hotplug sections. > > If we build the kernel with the gold linker, and with CONFIG_MEMORY_HOTPLUG=y, > we see that functions marked __meminit can end up outside of the > _stext/_etext range, and also outside of _sinittext/_einittext, eg: > > c000 T _stext > c09e A _etext > c09e3f18 T hash__vmemmap_create_mapping > c0ca T _sinittext > c0d00844 T _einittext > > This causes them to not be recognised as text by is_kernel_text(), and > prevents them being patched by jump_label (and presumably ftrace/kprobes > etc.). > > Fix it by adding MEM_KEEP() directives, mirroring what TEXT_TEXT does. > > This isn't a problem when CONFIG_MEMORY_HOTPLUG=n, because we use the > standard INIT_TEXT_SECTION() and EXIT_TEXT macros from vmlinux.lds.h. > > Signed-off-by: Michael Ellerman> Tested-by: Anton Blanchard Applied to powerpc next. https://git.kernel.org/powerpc/c/7de3b27bac47da9de08409df1d cheers
Re: [PATCH] powerpc: Ensure .mem(init|exit).text are within _stext/_etext
Hi, > In our linker script we open code the list of text sections, because > we need to include the __ftr_alt sections, which are arch-specific. > > This means we can't use TEXT_TEXT as defined in vmlinux.lds.h, and so > we don't have the MEM_KEEP() logic for memory hotplug sections. > > If we build the kernel with the gold linker, and with > CONFIG_MEMORY_HOTPLUG=y, we see that functions marked __meminit can > end up outside of the _stext/_etext range, and also outside of > _sinittext/_einittext, eg: > > c000 T _stext > c09e A _etext > c09e3f18 T hash__vmemmap_create_mapping > c0ca T _sinittext > c0d00844 T _einittext > > This causes them to not be recognised as text by is_kernel_text(), and > prevents them being patched by jump_label (and presumably > ftrace/kprobes etc.). > > Fix it by adding MEM_KEEP() directives, mirroring what TEXT_TEXT does. > > This isn't a problem when CONFIG_MEMORY_HOTPLUG=n, because we use the > standard INIT_TEXT_SECTION() and EXIT_TEXT macros from vmlinux.lds.h. Thanks Michael, looks good: Tested-by: Anton BlanchardAnton -- > Signed-off-by: Michael Ellerman > --- > arch/powerpc/kernel/vmlinux.lds.S | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/powerpc/kernel/vmlinux.lds.S > b/arch/powerpc/kernel/vmlinux.lds.S index b5fba689fca6..b59d75e194a5 > 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S > +++ b/arch/powerpc/kernel/vmlinux.lds.S > @@ -56,6 +56,8 @@ SECTIONS > KPROBES_TEXT > IRQENTRY_TEXT > SOFTIRQENTRY_TEXT > + MEM_KEEP(init.text) > + MEM_KEEP(exit.text) > > #ifdef CONFIG_PPC32 > *(.got1)
[PATCH] powerpc: Ensure .mem(init|exit).text are within _stext/_etext
In our linker script we open code the list of text sections, because we need to include the __ftr_alt sections, which are arch-specific. This means we can't use TEXT_TEXT as defined in vmlinux.lds.h, and so we don't have the MEM_KEEP() logic for memory hotplug sections. If we build the kernel with the gold linker, and with CONFIG_MEMORY_HOTPLUG=y, we see that functions marked __meminit can end up outside of the _stext/_etext range, and also outside of _sinittext/_einittext, eg: c000 T _stext c09e A _etext c09e3f18 T hash__vmemmap_create_mapping c0ca T _sinittext c0d00844 T _einittext This causes them to not be recognised as text by is_kernel_text(), and prevents them being patched by jump_label (and presumably ftrace/kprobes etc.). Fix it by adding MEM_KEEP() directives, mirroring what TEXT_TEXT does. This isn't a problem when CONFIG_MEMORY_HOTPLUG=n, because we use the standard INIT_TEXT_SECTION() and EXIT_TEXT macros from vmlinux.lds.h. Signed-off-by: Michael Ellerman--- arch/powerpc/kernel/vmlinux.lds.S | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S index b5fba689fca6..b59d75e194a5 100644 --- a/arch/powerpc/kernel/vmlinux.lds.S +++ b/arch/powerpc/kernel/vmlinux.lds.S @@ -56,6 +56,8 @@ SECTIONS KPROBES_TEXT IRQENTRY_TEXT SOFTIRQENTRY_TEXT + MEM_KEEP(init.text) + MEM_KEEP(exit.text) #ifdef CONFIG_PPC32 *(.got1) -- 2.7.4