| Message ID | 1455638631-3326518-2-git-send-email-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 16 February 2016 at 17:03, Arnd Bergmann <arnd@arndb.de> wrote: > The __start_rodata_section_aligned is only referenced by the > DEBUG_RODATA code, which is only used when the MMU is enabled, > but the definition fails on !MMU builds: > > arch/arm/kernel/vmlinux.lds:702: undefined symbol `SECTION_SHIFT' referenced in expression > > This hides the symbol whenever DEBUG_RODATA is disabled. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > Fixes: 64ac2e74f0b2 ("ARM: 8502/1: mm: mark section-aligned portion of rodata NX") > --- > arch/arm/kernel/vmlinux.lds.S | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S > index 2d7085ae1c2f..bb12933aee22 100644 > --- a/arch/arm/kernel/vmlinux.lds.S > +++ b/arch/arm/kernel/vmlinux.lds.S > @@ -322,12 +322,14 @@ SECTIONS > STABS_DEBUG > } > > +#ifdef CONFIG_DEBUG_RODATA > /* > * Without CONFIG_DEBUG_ALIGN_RODATA, __start_rodata_section_aligned will > * be the first section-aligned location after __start_rodata. Otherwise, > * it will be equal to __start_rodata. > */ > __start_rodata_section_aligned = ALIGN(__start_rodata, 1 << SECTION_SHIFT); > +#endif > Does PROVIDE(__start_rodata_section_aligned = xxx); do the trick as well? If it does, it's a bit cleaner.
On Tuesday 16 February 2016 17:12:52 Ard Biesheuvel wrote: > > +#ifdef CONFIG_DEBUG_RODATA > > /* > > * Without CONFIG_DEBUG_ALIGN_RODATA, __start_rodata_section_aligned will > > * be the first section-aligned location after __start_rodata. Otherwise, > > * it will be equal to __start_rodata. > > */ > > __start_rodata_section_aligned = ALIGN(__start_rodata, 1 << SECTION_SHIFT); > > +#endif > > > > Does > > PROVIDE(__start_rodata_section_aligned = xxx); > > do the trick as well? If it does, it's a bit cleaner. > I would assume not, as the problem is that SECTION_SHIFT is a macro that is not defined when the MMU is disabled. Arnd
On 16 February 2016 at 17:34, Arnd Bergmann <arnd@arndb.de> wrote: > On Tuesday 16 February 2016 17:12:52 Ard Biesheuvel wrote: >> > +#ifdef CONFIG_DEBUG_RODATA >> > /* >> > * Without CONFIG_DEBUG_ALIGN_RODATA, __start_rodata_section_aligned will >> > * be the first section-aligned location after __start_rodata. Otherwise, >> > * it will be equal to __start_rodata. >> > */ >> > __start_rodata_section_aligned = ALIGN(__start_rodata, 1 << SECTION_SHIFT); >> > +#endif >> > >> >> Does >> >> PROVIDE(__start_rodata_section_aligned = xxx); >> >> do the trick as well? If it does, it's a bit cleaner. >> > > I would assume not, as the problem is that SECTION_SHIFT is a macro that > is not defined when the MMU is disabled. > I just tested it myself, and it in fact does work. PROVIDE() means the expression is evaluated lazily, and SECTION_SHIFT is just an undefined identifier in the linker script scope if the preprocessor does not define it. Anyway, I don't have a strong preference, so ack either way.
diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index 2d7085ae1c2f..bb12933aee22 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -322,12 +322,14 @@ SECTIONS STABS_DEBUG } +#ifdef CONFIG_DEBUG_RODATA /* * Without CONFIG_DEBUG_ALIGN_RODATA, __start_rodata_section_aligned will * be the first section-aligned location after __start_rodata. Otherwise, * it will be equal to __start_rodata. */ __start_rodata_section_aligned = ALIGN(__start_rodata, 1 << SECTION_SHIFT); +#endif /* * These must never be empty
The __start_rodata_section_aligned is only referenced by the DEBUG_RODATA code, which is only used when the MMU is enabled, but the definition fails on !MMU builds: arch/arm/kernel/vmlinux.lds:702: undefined symbol `SECTION_SHIFT' referenced in expression This hides the symbol whenever DEBUG_RODATA is disabled. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Fixes: 64ac2e74f0b2 ("ARM: 8502/1: mm: mark section-aligned portion of rodata NX") --- arch/arm/kernel/vmlinux.lds.S | 2 ++ 1 file changed, 2 insertions(+)