Hi Ahmad, probably two copy'n'paste errors:
On Thu, Dec 11 2025 at 21:34 +0100, Ahmad Fatoum <[email protected]> wrote: > Splitting mmu_disable into two noinline function on a RK3568 leads to a > barebox crash, because the code has the implicit assumption that the > compiler won't generate memory accesses including spilling to stack. > > We can't guarantee this in C code, so implement the procedure in > assembly. > > While at it, drop mmu_early_disable(), which is unused, superfluous and > suffers from the same issue as old mmu_disable(). > > Signed-off-by: Ahmad Fatoum <[email protected]> > --- > arch/arm/cpu/cache-armv8.S | 54 ++++++++++++++++++++++++++++++++++++ > arch/arm/cpu/mmu_64.c | 27 +----------------- > arch/arm/include/asm/cache.h | 1 + > arch/arm/include/asm/mmu.h | 1 - > 4 files changed, 56 insertions(+), 27 deletions(-) > > diff --git a/arch/arm/cpu/cache-armv8.S b/arch/arm/cpu/cache-armv8.S > index 9d9e0fb585a1..b1847a2b9d1b 100644 > --- a/arch/arm/cpu/cache-armv8.S > +++ b/arch/arm/cpu/cache-armv8.S > @@ -9,6 +9,7 @@ > > #include <linux/linkage.h> > #include <init.h> > +#include <asm/system.h> > > /* > * void v8_flush_dcache_level(level) > @@ -120,6 +121,59 @@ ENTRY(v8_invalidate_dcache_all) > ret > ENDPROC(v8_invalidate_dcache_all) > > +/* > + * void v8_mmu_disable(void) > + * > + * Implements the equivalent of following C code: > + * > + * set_cr(get_cr() & ~(CR_M | CR_C)) > + * v8_flush_dcache_all(); > + * tlb_invalidate(); > + * > + * dsb(); > + * isb(); > + * > + * As D$ needs to be cleaned after it was disabled, this procedure > + * is not permitted to trigger memory access, including spilling > + * locals to stack. It's thus necessarily needs to be implemented > + * in assembly. > + */ > +.section .text.v8_mmu_disable > +ENTRY(v8_mmu_disable) > + mov x14, lr > + mov x1, #~(CR_C | CR_M) > + mrs x0, currentel > + lsr w0, w0, #2 /* w0 <- current exception level */ > + cmp w0, #0x1 > + b.eq 1f > + cmp w0, #0x2 > + b.eq 2f > +3: /* EL3 */ > + mrs x0, sctlr_el3 > + and x0, x0, x1 > + msr sctlr_el1, x0 Shouldn't the value be written back to sctlr_el3 instead of sctlr_el1? > + bl v8_flush_dcache_all > + tlbi alle3 > + b 0f > +2: /* EL2 */ > + mrs x0, sctlr_el2 > + and x0, x0, x1 > + msr sctlr_el1, x0 Same here? Best regards Ulrich > + bl v8_flush_dcache_all > + tlbi alle2 > + b 0f > +1: /* EL1 */ > + mrs x0, sctlr_el1 > + and x0, x0, x1 > + msr sctlr_el1, x0 > + bl v8_flush_dcache_all > + tlbi vmalle1 > +0: /* common prologue */ > + dsb sy > + isb > + ret x14 > +ENDPROC(v8_mmu_disable) > + > /* > * void v8_flush_dcache_range(start, end) > * > diff --git a/arch/arm/cpu/mmu_64.c b/arch/arm/cpu/mmu_64.c > index f22fcb5f8ea4..56c6a21f2b2a 100644 > --- a/arch/arm/cpu/mmu_64.c > +++ b/arch/arm/cpu/mmu_64.c > @@ -344,17 +344,7 @@ void __mmu_init(bool mmu_on) > > void mmu_disable(void) > { > - unsigned int cr; > - > - cr = get_cr(); > - cr &= ~(CR_M | CR_C); > - > - set_cr(cr); > - v8_flush_dcache_all(); > - tlb_invalidate(); > - > - dsb(); > - isb(); > + v8_mmu_disable(); > } > > void dma_inv_range(void *ptr, size_t size) > @@ -436,18 +426,3 @@ void mmu_early_enable(unsigned long membase, unsigned > long memsize, unsigned lon > > mmu_enable(); > } > - > -void mmu_early_disable(void) > -{ > - unsigned int cr; > - > - cr = get_cr(); > - cr &= ~(CR_M | CR_C); > - > - set_cr(cr); > - v8_flush_dcache_all(); > - tlb_invalidate(); > - > - dsb(); > - isb(); > -} > diff --git a/arch/arm/include/asm/cache.h b/arch/arm/include/asm/cache.h > index dd022c1f23f2..ea78ae123aec 100644 > --- a/arch/arm/include/asm/cache.h > +++ b/arch/arm/include/asm/cache.h > @@ -15,6 +15,7 @@ void v8_flush_dcache_all(void); > void v8_invalidate_dcache_all(void); > void v8_flush_dcache_range(unsigned long start, unsigned long end); > void v8_inv_dcache_range(unsigned long start, unsigned long end); > +void v8_mmu_disable(void); > > static inline void icache_invalidate(void) > { > diff --git a/arch/arm/include/asm/mmu.h b/arch/arm/include/asm/mmu.h > index eef6c53b5912..1fafbf9d77be 100644 > --- a/arch/arm/include/asm/mmu.h > +++ b/arch/arm/include/asm/mmu.h > @@ -65,6 +65,5 @@ void __dma_flush_range(unsigned long, unsigned long); > void __dma_inv_range(unsigned long, unsigned long); > > void mmu_early_enable(unsigned long membase, unsigned long memsize, unsigned > long barebox_base); > -void mmu_early_disable(void); > > #endif /* __ASM_MMU_H */ -- Pengutronix e.K. | Ulrich Ölmann | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
