| Message ID | 20220624150651.1358849-4-ardb@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: refactor boot flow | expand |
On Fri, Jun 24, 2022 at 05:06:33PM +0200, Ard Biesheuvel wrote: > Setting idmap_t0sz involves fiddling with the caches if done with the > MMU off. Since we will be creating an initial ID map with the MMU and > caches off, and the permanent ID map with the MMU and caches on, let's > move this assignment of idmap_t0sz out of the startup code, and replace > it with a macro that simply issues the three instructions needed to > calculate the value wherever it is needed before the MMU is turned on. > > Signed-off-by: Ard Biesheuvel <ardb@kernel.org> > --- > arch/arm64/include/asm/assembler.h | 14 ++++++++++++++ > arch/arm64/include/asm/mmu_context.h | 2 +- > arch/arm64/kernel/head.S | 13 +------------ > arch/arm64/mm/mmu.c | 4 +++- > arch/arm64/mm/proc.S | 2 +- > 5 files changed, 20 insertions(+), 15 deletions(-) > > diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h > index 8c5a61aeaf8e..9468f45c07a6 100644 > --- a/arch/arm64/include/asm/assembler.h > +++ b/arch/arm64/include/asm/assembler.h > @@ -359,6 +359,20 @@ alternative_cb_end > bfi \valreg, \t1sz, #TCR_T1SZ_OFFSET, #TCR_TxSZ_WIDTH > .endm > > +/* > + * idmap_get_t0sz - get the T0SZ value needed to cover the ID map > + * > + * Calculate the maximum allowed value for TCR_EL1.T0SZ so that the > + * entire ID map region can be mapped. As T0SZ == (64 - #bits used), > + * this number conveniently equals the number of leading zeroes in > + * the physical address of _end. > + */ > + .macro idmap_get_t0sz, reg > + adrp \reg, _end > + orr \reg, \reg, #(1 << VA_BITS_MIN) - 1 > + clz \reg, \reg > + .endm I understand we ORR in the VA_BITS_MIN case so that we don't calculate a smaller size than we'll create tables for. That might be worht a comment, but either way: Acked-by: Mark Rutland <mark.rutland@arm.com> Mark. > + > /* > * tcr_compute_pa_size - set TCR.(I)PS to the highest supported > * ID_AA64MMFR0_EL1.PARange value > diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h > index 6770667b34a3..6ac0086ebb1a 100644 > --- a/arch/arm64/include/asm/mmu_context.h > +++ b/arch/arm64/include/asm/mmu_context.h > @@ -60,7 +60,7 @@ static inline void cpu_switch_mm(pgd_t *pgd, struct mm_struct *mm) > * TCR_T0SZ(VA_BITS), unless system RAM is positioned very high in > * physical memory, in which case it will be smaller. > */ > -extern u64 idmap_t0sz; > +extern int idmap_t0sz; > extern u64 idmap_ptrs_per_pgd; > > /* > diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S > index dc07858eb673..7f361bc72d12 100644 > --- a/arch/arm64/kernel/head.S > +++ b/arch/arm64/kernel/head.S > @@ -299,22 +299,11 @@ SYM_FUNC_START_LOCAL(__create_page_tables) > * physical address space. So for the ID map, use an extended virtual > * range in that case, and configure an additional translation level > * if needed. > - * > - * Calculate the maximum allowed value for TCR_EL1.T0SZ so that the > - * entire ID map region can be mapped. As T0SZ == (64 - #bits used), > - * this number conveniently equals the number of leading zeroes in > - * the physical address of __idmap_text_end. > */ > - adrp x5, __idmap_text_end > - clz x5, x5 > + idmap_get_t0sz x5 > cmp x5, TCR_T0SZ(VA_BITS_MIN) // default T0SZ small enough? > b.ge 1f // .. then skip VA range extension > > - adr_l x6, idmap_t0sz > - str x5, [x6] > - dmb sy > - dc ivac, x6 // Invalidate potentially stale cache line > - > #if (VA_BITS < 48) > #define EXTRA_SHIFT (PGDIR_SHIFT + PAGE_SHIFT - 3) > #define EXTRA_PTRS (1 << (PHYS_MASK_SHIFT - EXTRA_SHIFT)) > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index a6392656d589..f875c4954e22 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -43,7 +43,7 @@ > #define NO_CONT_MAPPINGS BIT(1) > #define NO_EXEC_MAPPINGS BIT(2) /* assumes FEAT_HPDS is not used */ > > -u64 idmap_t0sz = TCR_T0SZ(VA_BITS_MIN); > +int idmap_t0sz __ro_after_init; > u64 idmap_ptrs_per_pgd = PTRS_PER_PGD; > > #if VA_BITS > 48 > @@ -774,6 +774,8 @@ void __init paging_init(void) > { > pgd_t *pgdp = pgd_set_fixmap(__pa_symbol(swapper_pg_dir)); > > + idmap_t0sz = 63UL - __fls(__pa_symbol(_end) | GENMASK(VA_BITS_MIN - 1, 0)); > + > map_kernel(pgdp); > map_mem(pgdp); > > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > index 972ce8d7f2c5..97cd67697212 100644 > --- a/arch/arm64/mm/proc.S > +++ b/arch/arm64/mm/proc.S > @@ -470,7 +470,7 @@ SYM_FUNC_START(__cpu_setup) > add x9, x9, #64 > tcr_set_t1sz tcr, x9 > #else > - ldr_l x9, idmap_t0sz > + idmap_get_t0sz x9 > #endif > tcr_set_t0sz tcr, x9 > > -- > 2.35.1 >
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index 8c5a61aeaf8e..9468f45c07a6 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -359,6 +359,20 @@ alternative_cb_end bfi \valreg, \t1sz, #TCR_T1SZ_OFFSET, #TCR_TxSZ_WIDTH .endm +/* + * idmap_get_t0sz - get the T0SZ value needed to cover the ID map + * + * Calculate the maximum allowed value for TCR_EL1.T0SZ so that the + * entire ID map region can be mapped. As T0SZ == (64 - #bits used), + * this number conveniently equals the number of leading zeroes in + * the physical address of _end. + */ + .macro idmap_get_t0sz, reg + adrp \reg, _end + orr \reg, \reg, #(1 << VA_BITS_MIN) - 1 + clz \reg, \reg + .endm + /* * tcr_compute_pa_size - set TCR.(I)PS to the highest supported * ID_AA64MMFR0_EL1.PARange value diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index 6770667b34a3..6ac0086ebb1a 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -60,7 +60,7 @@ static inline void cpu_switch_mm(pgd_t *pgd, struct mm_struct *mm) * TCR_T0SZ(VA_BITS), unless system RAM is positioned very high in * physical memory, in which case it will be smaller. */ -extern u64 idmap_t0sz; +extern int idmap_t0sz; extern u64 idmap_ptrs_per_pgd; /* diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index dc07858eb673..7f361bc72d12 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -299,22 +299,11 @@ SYM_FUNC_START_LOCAL(__create_page_tables) * physical address space. So for the ID map, use an extended virtual * range in that case, and configure an additional translation level * if needed. - * - * Calculate the maximum allowed value for TCR_EL1.T0SZ so that the - * entire ID map region can be mapped. As T0SZ == (64 - #bits used), - * this number conveniently equals the number of leading zeroes in - * the physical address of __idmap_text_end. */ - adrp x5, __idmap_text_end - clz x5, x5 + idmap_get_t0sz x5 cmp x5, TCR_T0SZ(VA_BITS_MIN) // default T0SZ small enough? b.ge 1f // .. then skip VA range extension - adr_l x6, idmap_t0sz - str x5, [x6] - dmb sy - dc ivac, x6 // Invalidate potentially stale cache line - #if (VA_BITS < 48) #define EXTRA_SHIFT (PGDIR_SHIFT + PAGE_SHIFT - 3) #define EXTRA_PTRS (1 << (PHYS_MASK_SHIFT - EXTRA_SHIFT)) diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index a6392656d589..f875c4954e22 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -43,7 +43,7 @@ #define NO_CONT_MAPPINGS BIT(1) #define NO_EXEC_MAPPINGS BIT(2) /* assumes FEAT_HPDS is not used */ -u64 idmap_t0sz = TCR_T0SZ(VA_BITS_MIN); +int idmap_t0sz __ro_after_init; u64 idmap_ptrs_per_pgd = PTRS_PER_PGD; #if VA_BITS > 48 @@ -774,6 +774,8 @@ void __init paging_init(void) { pgd_t *pgdp = pgd_set_fixmap(__pa_symbol(swapper_pg_dir)); + idmap_t0sz = 63UL - __fls(__pa_symbol(_end) | GENMASK(VA_BITS_MIN - 1, 0)); + map_kernel(pgdp); map_mem(pgdp); diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 972ce8d7f2c5..97cd67697212 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -470,7 +470,7 @@ SYM_FUNC_START(__cpu_setup) add x9, x9, #64 tcr_set_t1sz tcr, x9 #else - ldr_l x9, idmap_t0sz + idmap_get_t0sz x9 #endif tcr_set_t0sz tcr, x9
Setting idmap_t0sz involves fiddling with the caches if done with the MMU off. Since we will be creating an initial ID map with the MMU and caches off, and the permanent ID map with the MMU and caches on, let's move this assignment of idmap_t0sz out of the startup code, and replace it with a macro that simply issues the three instructions needed to calculate the value wherever it is needed before the MMU is turned on. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/arm64/include/asm/assembler.h | 14 ++++++++++++++ arch/arm64/include/asm/mmu_context.h | 2 +- arch/arm64/kernel/head.S | 13 +------------ arch/arm64/mm/mmu.c | 4 +++- arch/arm64/mm/proc.S | 2 +- 5 files changed, 20 insertions(+), 15 deletions(-)