| Message ID | 1427101646-465-2-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
On 23 March 2015 at 10:07, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > The implementation of soft_restart() and its subordinate functions > setup_mm_for_reboot(), cpu_soft_restart() and cpu_reset() have > non-trivial dependencies on the state of the caches and the MMU, > making them fragile from a maintenance pov. However, soft_restart() > isn't actually called anywhere, so just remove the whole bunch. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Hmm, I guess kexec will be using soft_restart() so never mind this patch. > --- > arch/arm64/include/asm/mmu.h | 1 - > arch/arm64/include/asm/proc-fns.h | 3 --- > arch/arm64/include/asm/system_misc.h | 1 - > arch/arm64/kernel/process.c | 12 +----------- > arch/arm64/mm/mmu.c | 11 ----------- > arch/arm64/mm/proc.S | 33 --------------------------------- > 6 files changed, 1 insertion(+), 60 deletions(-) > > diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h > index 3d311761e3c2..99064c075fc6 100644 > --- a/arch/arm64/include/asm/mmu.h > +++ b/arch/arm64/include/asm/mmu.h > @@ -28,7 +28,6 @@ typedef struct { > #define ASID(mm) ((mm)->context.id & 0xffff) > > extern void paging_init(void); > -extern void setup_mm_for_reboot(void); > extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt); > extern void init_mem_pgprot(void); > extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, > diff --git a/arch/arm64/include/asm/proc-fns.h b/arch/arm64/include/asm/proc-fns.h > index 4d9ede7b6361..ab334467c6a4 100644 > --- a/arch/arm64/include/asm/proc-fns.h > +++ b/arch/arm64/include/asm/proc-fns.h > @@ -31,9 +31,6 @@ struct cpu_suspend_ctx; > extern void cpu_cache_off(void); > extern void cpu_do_idle(void); > extern void cpu_do_switch_mm(unsigned long pgd_phys, struct mm_struct *mm); > -extern void cpu_reset(unsigned long addr) __attribute__((noreturn)); > -void cpu_soft_restart(phys_addr_t cpu_reset, > - unsigned long addr) __attribute__((noreturn)); > extern void cpu_do_suspend(struct cpu_suspend_ctx *ptr); > extern u64 cpu_do_resume(phys_addr_t ptr, u64 idmap_ttbr); > > diff --git a/arch/arm64/include/asm/system_misc.h b/arch/arm64/include/asm/system_misc.h > index 7a18fabbe0f6..659fbf5925de 100644 > --- a/arch/arm64/include/asm/system_misc.h > +++ b/arch/arm64/include/asm/system_misc.h > @@ -41,7 +41,6 @@ struct mm_struct; > extern void show_pte(struct mm_struct *mm, unsigned long addr); > extern void __show_regs(struct pt_regs *); > > -void soft_restart(unsigned long); > extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd); > > #define UDBG_UNDEFINED (1 << 0) > diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c > index c6b1f3b96f45..c506bee6b613 100644 > --- a/arch/arm64/kernel/process.c > +++ b/arch/arm64/kernel/process.c > @@ -58,14 +58,6 @@ unsigned long __stack_chk_guard __read_mostly; > EXPORT_SYMBOL(__stack_chk_guard); > #endif > > -void soft_restart(unsigned long addr) > -{ > - setup_mm_for_reboot(); > - cpu_soft_restart(virt_to_phys(cpu_reset), addr); > - /* Should never get here */ > - BUG(); > -} > - > /* > * Function pointers to optional machine specific functions > */ > @@ -136,9 +128,7 @@ void machine_power_off(void) > > /* > * Restart requires that the secondary CPUs stop performing any activity > - * while the primary CPU resets the system. Systems with a single CPU can > - * use soft_restart() as their machine descriptor's .restart hook, since that > - * will cause the only available CPU to reset. Systems with multiple CPUs must > + * while the primary CPU resets the system. Systems with multiple CPUs must > * provide a HW restart implementation, to ensure that all CPUs reset at once. > * This is required so that any code running after reset on the primary CPU > * doesn't have to co-ordinate with other CPUs to ensure they aren't still > diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c > index 428aaf86c95b..15ac396229d5 100644 > --- a/arch/arm64/mm/mmu.c > +++ b/arch/arm64/mm/mmu.c > @@ -460,17 +460,6 @@ void __init paging_init(void) > } > > /* > - * Enable the identity mapping to allow the MMU disabling. > - */ > -void setup_mm_for_reboot(void) > -{ > - cpu_set_reserved_ttbr0(); > - flush_tlb_all(); > - cpu_set_idmap_tcr_t0sz(); > - cpu_switch_mm(idmap_pg_dir, &init_mm); > -} > - > -/* > * Check whether a kernel address is valid (derived from arch/x86/). > */ > int kern_addr_valid(unsigned long addr) > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S > index cdd754e19b9b..a2059ec61463 100644 > --- a/arch/arm64/mm/proc.S > +++ b/arch/arm64/mm/proc.S > @@ -59,39 +59,6 @@ ENTRY(cpu_cache_off) > ENDPROC(cpu_cache_off) > > /* > - * cpu_reset(loc) > - * > - * Perform a soft reset of the system. Put the CPU into the same state > - * as it would be if it had been reset, and branch to what would be the > - * reset vector. It must be executed with the flat identity mapping. > - * > - * - loc - location to jump to for soft reset > - */ > - .align 5 > -ENTRY(cpu_reset) > - mrs x1, sctlr_el1 > - bic x1, x1, #1 > - msr sctlr_el1, x1 // disable the MMU > - isb > - ret x0 > -ENDPROC(cpu_reset) > - > -ENTRY(cpu_soft_restart) > - /* Save address of cpu_reset() and reset address */ > - mov x19, x0 > - mov x20, x1 > - > - /* Turn D-cache off */ > - bl cpu_cache_off > - > - /* Push out all dirty data, and ensure cache is empty */ > - bl flush_cache_all > - > - mov x0, x20 > - ret x19 > -ENDPROC(cpu_soft_restart) > - > -/* > * cpu_do_idle() > * > * Idle the processor (wait for interrupt). > -- > 1.8.3.2 >
diff --git a/arch/arm64/include/asm/mmu.h b/arch/arm64/include/asm/mmu.h index 3d311761e3c2..99064c075fc6 100644 --- a/arch/arm64/include/asm/mmu.h +++ b/arch/arm64/include/asm/mmu.h @@ -28,7 +28,6 @@ typedef struct { #define ASID(mm) ((mm)->context.id & 0xffff) extern void paging_init(void); -extern void setup_mm_for_reboot(void); extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt); extern void init_mem_pgprot(void); extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys, diff --git a/arch/arm64/include/asm/proc-fns.h b/arch/arm64/include/asm/proc-fns.h index 4d9ede7b6361..ab334467c6a4 100644 --- a/arch/arm64/include/asm/proc-fns.h +++ b/arch/arm64/include/asm/proc-fns.h @@ -31,9 +31,6 @@ struct cpu_suspend_ctx; extern void cpu_cache_off(void); extern void cpu_do_idle(void); extern void cpu_do_switch_mm(unsigned long pgd_phys, struct mm_struct *mm); -extern void cpu_reset(unsigned long addr) __attribute__((noreturn)); -void cpu_soft_restart(phys_addr_t cpu_reset, - unsigned long addr) __attribute__((noreturn)); extern void cpu_do_suspend(struct cpu_suspend_ctx *ptr); extern u64 cpu_do_resume(phys_addr_t ptr, u64 idmap_ttbr); diff --git a/arch/arm64/include/asm/system_misc.h b/arch/arm64/include/asm/system_misc.h index 7a18fabbe0f6..659fbf5925de 100644 --- a/arch/arm64/include/asm/system_misc.h +++ b/arch/arm64/include/asm/system_misc.h @@ -41,7 +41,6 @@ struct mm_struct; extern void show_pte(struct mm_struct *mm, unsigned long addr); extern void __show_regs(struct pt_regs *); -void soft_restart(unsigned long); extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd); #define UDBG_UNDEFINED (1 << 0) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index c6b1f3b96f45..c506bee6b613 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -58,14 +58,6 @@ unsigned long __stack_chk_guard __read_mostly; EXPORT_SYMBOL(__stack_chk_guard); #endif -void soft_restart(unsigned long addr) -{ - setup_mm_for_reboot(); - cpu_soft_restart(virt_to_phys(cpu_reset), addr); - /* Should never get here */ - BUG(); -} - /* * Function pointers to optional machine specific functions */ @@ -136,9 +128,7 @@ void machine_power_off(void) /* * Restart requires that the secondary CPUs stop performing any activity - * while the primary CPU resets the system. Systems with a single CPU can - * use soft_restart() as their machine descriptor's .restart hook, since that - * will cause the only available CPU to reset. Systems with multiple CPUs must + * while the primary CPU resets the system. Systems with multiple CPUs must * provide a HW restart implementation, to ensure that all CPUs reset at once. * This is required so that any code running after reset on the primary CPU * doesn't have to co-ordinate with other CPUs to ensure they aren't still diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 428aaf86c95b..15ac396229d5 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -460,17 +460,6 @@ void __init paging_init(void) } /* - * Enable the identity mapping to allow the MMU disabling. - */ -void setup_mm_for_reboot(void) -{ - cpu_set_reserved_ttbr0(); - flush_tlb_all(); - cpu_set_idmap_tcr_t0sz(); - cpu_switch_mm(idmap_pg_dir, &init_mm); -} - -/* * Check whether a kernel address is valid (derived from arch/x86/). */ int kern_addr_valid(unsigned long addr) diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index cdd754e19b9b..a2059ec61463 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -59,39 +59,6 @@ ENTRY(cpu_cache_off) ENDPROC(cpu_cache_off) /* - * cpu_reset(loc) - * - * Perform a soft reset of the system. Put the CPU into the same state - * as it would be if it had been reset, and branch to what would be the - * reset vector. It must be executed with the flat identity mapping. - * - * - loc - location to jump to for soft reset - */ - .align 5 -ENTRY(cpu_reset) - mrs x1, sctlr_el1 - bic x1, x1, #1 - msr sctlr_el1, x1 // disable the MMU - isb - ret x0 -ENDPROC(cpu_reset) - -ENTRY(cpu_soft_restart) - /* Save address of cpu_reset() and reset address */ - mov x19, x0 - mov x20, x1 - - /* Turn D-cache off */ - bl cpu_cache_off - - /* Push out all dirty data, and ensure cache is empty */ - bl flush_cache_all - - mov x0, x20 - ret x19 -ENDPROC(cpu_soft_restart) - -/* * cpu_do_idle() * * Idle the processor (wait for interrupt).
The implementation of soft_restart() and its subordinate functions setup_mm_for_reboot(), cpu_soft_restart() and cpu_reset() have non-trivial dependencies on the state of the caches and the MMU, making them fragile from a maintenance pov. However, soft_restart() isn't actually called anywhere, so just remove the whole bunch. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- arch/arm64/include/asm/mmu.h | 1 - arch/arm64/include/asm/proc-fns.h | 3 --- arch/arm64/include/asm/system_misc.h | 1 - arch/arm64/kernel/process.c | 12 +----------- arch/arm64/mm/mmu.c | 11 ----------- arch/arm64/mm/proc.S | 33 --------------------------------- 6 files changed, 1 insertion(+), 60 deletions(-)