| Message ID | 1358162123-30113-1-git-send-email-u.kleine-koenig@pengutronix.de |
|---|---|
| State | New |
| Headers | show |
On Mon, 14 Jan 2013, Uwe Kleine-König wrote: > Some ARM cores are not capable to run in ARM mode (e.g. Cortex-M3). So > obviously these cannot enter the kernel in ARM mode. Make an exception > for them and let them enter in THUMB mode. > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Acked-by: Nicolas Pitre <nico@linaro.org> > --- > Changes since (implicit) v1, > id: 1357904397-8476-1-git-send-email-u.kleine-koenig@pengutronix.de: > > - drop modification to entry for MMU machines > - don't select user-visible symbols > - rename THUMBONLY_CPU to CPU_THUMBONLY > - move CPU_THUMBONLY definition further down in arch/arm/mm/Kconfig > > arch/arm/Kconfig | 3 ++- > arch/arm/kernel/head-nommu.S | 8 +++++++- > arch/arm/mm/Kconfig | 9 ++++++++- > 3 files changed, 17 insertions(+), 3 deletions(-) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 67874b8..e04c779 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -1656,8 +1656,9 @@ config HZ > default 100 > > config THUMB2_KERNEL > - bool "Compile the kernel in Thumb-2 mode" > + bool "Compile the kernel in Thumb-2 mode" if !CPU_THUMBONLY > depends on CPU_V7 && !CPU_V6 && !CPU_V6K > + default y if CPU_THUMBONLY > select AEABI > select ARM_ASM_UNIFIED > select ARM_UNWIND > diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S > index 3782320..e8ecae2 100644 > --- a/arch/arm/kernel/head-nommu.S > +++ b/arch/arm/kernel/head-nommu.S > @@ -32,15 +32,21 @@ > * numbers for r1. > * > */ > - .arm > > __HEAD > + > +#ifdef CONFIG_CPU_THUMBONLY > + .thumb > +ENTRY(stext) > +#else > + .arm > ENTRY(stext) > > THUMB( adr r9, BSYM(1f) ) @ Kernel is always entered in ARM. > THUMB( bx r9 ) @ If this is a Thumb-2 kernel, > THUMB( .thumb ) @ switch to Thumb now. > THUMB(1: ) > +#endif > > setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode > @ and irqs disabled > diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig > index 3fd629d..8defd63 100644 > --- a/arch/arm/mm/Kconfig > +++ b/arch/arm/mm/Kconfig > @@ -397,6 +397,13 @@ config CPU_V7 > select CPU_PABRT_V7 > select CPU_TLB_V7 if MMU > > +config CPU_THUMBONLY > + bool > + # There are no CPUs available with MMU that don't implement an ARM ISA: > + depends on !MMU > + help > + Select this if your CPU doesn't support the 32 bit ARM instructions. > + > # Figure out what processor architecture version we should be using. > # This defines the compiler instruction set which depends on the machine type. > config CPU_32v3 > @@ -608,7 +615,7 @@ config ARCH_DMA_ADDR_T_64BIT > bool > > config ARM_THUMB > - bool "Support Thumb user binaries" > + bool "Support Thumb user binaries" if !CPU_THUMBONLY > depends on CPU_ARM720T || CPU_ARM740T || CPU_ARM920T || CPU_ARM922T || CPU_ARM925T || CPU_ARM926T || CPU_ARM940T || CPU_ARM946E || CPU_ARM1020 || CPU_ARM1020E || CPU_ARM1022 || CPU_ARM1026 || CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_V6 || CPU_V6K || CPU_V7 || CPU_FEROCEON > default y > help > -- > 1.7.10.4 >
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 67874b8..e04c779 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -1656,8 +1656,9 @@ config HZ default 100 config THUMB2_KERNEL - bool "Compile the kernel in Thumb-2 mode" + bool "Compile the kernel in Thumb-2 mode" if !CPU_THUMBONLY depends on CPU_V7 && !CPU_V6 && !CPU_V6K + default y if CPU_THUMBONLY select AEABI select ARM_ASM_UNIFIED select ARM_UNWIND diff --git a/arch/arm/kernel/head-nommu.S b/arch/arm/kernel/head-nommu.S index 3782320..e8ecae2 100644 --- a/arch/arm/kernel/head-nommu.S +++ b/arch/arm/kernel/head-nommu.S @@ -32,15 +32,21 @@ * numbers for r1. * */ - .arm __HEAD + +#ifdef CONFIG_CPU_THUMBONLY + .thumb +ENTRY(stext) +#else + .arm ENTRY(stext) THUMB( adr r9, BSYM(1f) ) @ Kernel is always entered in ARM. THUMB( bx r9 ) @ If this is a Thumb-2 kernel, THUMB( .thumb ) @ switch to Thumb now. THUMB(1: ) +#endif setmode PSR_F_BIT | PSR_I_BIT | SVC_MODE, r9 @ ensure svc mode @ and irqs disabled diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index 3fd629d..8defd63 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -397,6 +397,13 @@ config CPU_V7 select CPU_PABRT_V7 select CPU_TLB_V7 if MMU +config CPU_THUMBONLY + bool + # There are no CPUs available with MMU that don't implement an ARM ISA: + depends on !MMU + help + Select this if your CPU doesn't support the 32 bit ARM instructions. + # Figure out what processor architecture version we should be using. # This defines the compiler instruction set which depends on the machine type. config CPU_32v3 @@ -608,7 +615,7 @@ config ARCH_DMA_ADDR_T_64BIT bool config ARM_THUMB - bool "Support Thumb user binaries" + bool "Support Thumb user binaries" if !CPU_THUMBONLY depends on CPU_ARM720T || CPU_ARM740T || CPU_ARM920T || CPU_ARM922T || CPU_ARM925T || CPU_ARM926T || CPU_ARM940T || CPU_ARM946E || CPU_ARM1020 || CPU_ARM1020E || CPU_ARM1022 || CPU_ARM1026 || CPU_XSCALE || CPU_XSC3 || CPU_MOHAWK || CPU_V6 || CPU_V6K || CPU_V7 || CPU_FEROCEON default y help
Some ARM cores are not capable to run in ARM mode (e.g. Cortex-M3). So obviously these cannot enter the kernel in ARM mode. Make an exception for them and let them enter in THUMB mode. Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> --- Changes since (implicit) v1, id: 1357904397-8476-1-git-send-email-u.kleine-koenig@pengutronix.de: - drop modification to entry for MMU machines - don't select user-visible symbols - rename THUMBONLY_CPU to CPU_THUMBONLY - move CPU_THUMBONLY definition further down in arch/arm/mm/Kconfig arch/arm/Kconfig | 3 ++- arch/arm/kernel/head-nommu.S | 8 +++++++- arch/arm/mm/Kconfig | 9 ++++++++- 3 files changed, 17 insertions(+), 3 deletions(-)