| Message ID | 20201124195940.27061-3-samitolvanen@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | scs: switch to vmapped shadow stacks | expand |
On Tue, Nov 24, 2020 at 11:59:40AM -0800, Sami Tolvanen wrote: > Use scs_alloc() to allocate also IRQ and SDEI shadow stacks instead of > using statically allocated stacks. > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > --- > arch/arm64/kernel/Makefile | 1 - > arch/arm64/kernel/entry.S | 6 ++-- > arch/arm64/kernel/irq.c | 19 ++++++++++ > arch/arm64/kernel/scs.c | 16 --------- > arch/arm64/kernel/sdei.c | 71 +++++++++++++++++++++++++++++++------- > include/linux/scs.h | 4 --- > 6 files changed, 81 insertions(+), 36 deletions(-) > delete mode 100644 arch/arm64/kernel/scs.c [...] > @@ -70,18 +97,40 @@ static int _init_sdei_stack(unsigned long * __percpu *ptr, int cpu) > return 0; > } > > +static int _init_sdei_scs(unsigned long * __percpu *ptr, int cpu) > +{ > + void *s; > + > + s = scs_alloc(cpu_to_node(cpu)); > + if (!s) > + return -ENOMEM; > + per_cpu(*ptr, cpu) = s; > + > + return 0; > +} > + > static int init_sdei_stacks(void) > { > int cpu; > int err = 0; > > for_each_possible_cpu(cpu) { > - err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu); > - if (err) > - break; > - err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu); > - if (err) > - break; > + if (IS_ENABLED(CONFIG_VMAP_STACK)) { > + err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu); > + if (err) > + break; > + err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu); > + if (err) > + break; > + } > + if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) { > + err = _init_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu); > + if (err) > + break; > + err = _init_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu); > + if (err) > + break; This looks ok to me, but I think it would be better to follow the same approach as you have for the IRQ stacks and instead have a separate init_sdei_scs() function (similarly for the free() path), which means you can simply the IS_ENABLED() checks too. Either way: Acked-by: Will Deacon <will@kernel.org> Will
On Mon, Nov 30, 2020 at 3:49 AM Will Deacon <will@kernel.org> wrote: > > On Tue, Nov 24, 2020 at 11:59:40AM -0800, Sami Tolvanen wrote: > > Use scs_alloc() to allocate also IRQ and SDEI shadow stacks instead of > > using statically allocated stacks. > > > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > > --- > > arch/arm64/kernel/Makefile | 1 - > > arch/arm64/kernel/entry.S | 6 ++-- > > arch/arm64/kernel/irq.c | 19 ++++++++++ > > arch/arm64/kernel/scs.c | 16 --------- > > arch/arm64/kernel/sdei.c | 71 +++++++++++++++++++++++++++++++------- > > include/linux/scs.h | 4 --- > > 6 files changed, 81 insertions(+), 36 deletions(-) > > delete mode 100644 arch/arm64/kernel/scs.c > > [...] > > > @@ -70,18 +97,40 @@ static int _init_sdei_stack(unsigned long * __percpu *ptr, int cpu) > > return 0; > > } > > > > +static int _init_sdei_scs(unsigned long * __percpu *ptr, int cpu) > > +{ > > + void *s; > > + > > + s = scs_alloc(cpu_to_node(cpu)); > > + if (!s) > > + return -ENOMEM; > > + per_cpu(*ptr, cpu) = s; > > + > > + return 0; > > +} > > + > > static int init_sdei_stacks(void) > > { > > int cpu; > > int err = 0; > > > > for_each_possible_cpu(cpu) { > > - err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu); > > - if (err) > > - break; > > - err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu); > > - if (err) > > - break; > > + if (IS_ENABLED(CONFIG_VMAP_STACK)) { > > + err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu); > > + if (err) > > + break; > > + err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu); > > + if (err) > > + break; > > + } > > + if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) { > > + err = _init_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu); > > + if (err) > > + break; > > + err = _init_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu); > > + if (err) > > + break; > > This looks ok to me, but I think it would be better to follow the same > approach as you have for the IRQ stacks and instead have a separate > init_sdei_scs() function (similarly for the free() path), which means > you can simply the IS_ENABLED() checks too. OK, I can change this in v3. It makes error handling in sdei_arch_get_entry_point() a bit more awkward though. We'll need something like this: if (IS_ENABLED(CONFIG_VMAP_STACK)) { if (init_sdei_stacks()) return 0; } if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) { if (init_sdei_scs()) { if (IS_ENABLED(CONFIG_VMAP_STACK)) free_sdei_stacks(); return 0; } } Sami
On Mon, Nov 30, 2020 at 01:13:07PM -0800, Sami Tolvanen wrote: > On Mon, Nov 30, 2020 at 3:49 AM Will Deacon <will@kernel.org> wrote: > > > > On Tue, Nov 24, 2020 at 11:59:40AM -0800, Sami Tolvanen wrote: > > > Use scs_alloc() to allocate also IRQ and SDEI shadow stacks instead of > > > using statically allocated stacks. > > > > > > Signed-off-by: Sami Tolvanen <samitolvanen@google.com> > > > --- > > > arch/arm64/kernel/Makefile | 1 - > > > arch/arm64/kernel/entry.S | 6 ++-- > > > arch/arm64/kernel/irq.c | 19 ++++++++++ > > > arch/arm64/kernel/scs.c | 16 --------- > > > arch/arm64/kernel/sdei.c | 71 +++++++++++++++++++++++++++++++------- > > > include/linux/scs.h | 4 --- > > > 6 files changed, 81 insertions(+), 36 deletions(-) > > > delete mode 100644 arch/arm64/kernel/scs.c > > > > [...] > > > > > @@ -70,18 +97,40 @@ static int _init_sdei_stack(unsigned long * __percpu *ptr, int cpu) > > > return 0; > > > } > > > > > > +static int _init_sdei_scs(unsigned long * __percpu *ptr, int cpu) > > > +{ > > > + void *s; > > > + > > > + s = scs_alloc(cpu_to_node(cpu)); > > > + if (!s) > > > + return -ENOMEM; > > > + per_cpu(*ptr, cpu) = s; > > > + > > > + return 0; > > > +} > > > + > > > static int init_sdei_stacks(void) > > > { > > > int cpu; > > > int err = 0; > > > > > > for_each_possible_cpu(cpu) { > > > - err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu); > > > - if (err) > > > - break; > > > - err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu); > > > - if (err) > > > - break; > > > + if (IS_ENABLED(CONFIG_VMAP_STACK)) { > > > + err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu); > > > + if (err) > > > + break; > > > + err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu); > > > + if (err) > > > + break; > > > + } > > > + if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) { > > > + err = _init_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu); > > > + if (err) > > > + break; > > > + err = _init_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu); > > > + if (err) > > > + break; > > > > This looks ok to me, but I think it would be better to follow the same > > approach as you have for the IRQ stacks and instead have a separate > > init_sdei_scs() function (similarly for the free() path), which means > > you can simply the IS_ENABLED() checks too. > > OK, I can change this in v3. It makes error handling in > sdei_arch_get_entry_point() a bit more awkward though. We'll need > something like this: > > if (IS_ENABLED(CONFIG_VMAP_STACK)) { > if (init_sdei_stacks()) > return 0; > } > > if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) { > if (init_sdei_scs()) { > if (IS_ENABLED(CONFIG_VMAP_STACK)) > free_sdei_stacks(); > return 0; > } Can you push the IS_ENABLED() checks into their respective functions? Then you can do something like: if (init_sdei_stacks()) return 0; if (init_sdei_scs()) goto out_free_stacks; ... out_free_stacks: free_sdei_stacks(); return 0; Will
On Tue, Dec 01, 2020 at 10:18:19AM +0000, Will Deacon wrote: > On Mon, Nov 30, 2020 at 01:13:07PM -0800, Sami Tolvanen wrote: > > On Mon, Nov 30, 2020 at 3:49 AM Will Deacon <will@kernel.org> wrote: > > > On Tue, Nov 24, 2020 at 11:59:40AM -0800, Sami Tolvanen wrote: > > > > for_each_possible_cpu(cpu) { > > > > - err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu); > > > > - if (err) > > > > - break; > > > > - err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu); > > > > - if (err) > > > > - break; > > > > + if (IS_ENABLED(CONFIG_VMAP_STACK)) { > > > > + err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu); > > > > + if (err) > > > > + break; > > > > + err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu); > > > > + if (err) > > > > + break; > > > > + } > > > > + if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) { > > > > + err = _init_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu); > > > > + if (err) > > > > + break; > > > > + err = _init_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu); > > > > + if (err) > > > > + break; > > > > > > This looks ok to me, but I think it would be better to follow the same > > > approach as you have for the IRQ stacks and instead have a separate > > > init_sdei_scs() function (similarly for the free() path), which means > > > you can simply the IS_ENABLED() checks too. > > > > OK, I can change this in v3. It makes error handling in > > sdei_arch_get_entry_point() a bit more awkward though. We'll need > > something like this: > > > > if (IS_ENABLED(CONFIG_VMAP_STACK)) { > > if (init_sdei_stacks()) > > return 0; > > } > > > > if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) { > > if (init_sdei_scs()) { > > if (IS_ENABLED(CONFIG_VMAP_STACK)) > > free_sdei_stacks(); > > return 0; > > } > > Can you push the IS_ENABLED() checks into their respective functions? > Then you can do something like: > > if (init_sdei_stacks()) > return 0; > > if (init_sdei_scs()) > goto out_free_stacks; > > ... > > out_free_stacks: > free_sdei_stacks(); > return 0; Wait, I see you already posted a v3. Maybe I can just hack this up on top... Will
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index bbaf0bc4ad60..86364ab6f13f 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -58,7 +58,6 @@ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o obj-$(CONFIG_CRASH_CORE) += crash_core.o obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o obj-$(CONFIG_ARM64_PTR_AUTH) += pointer_auth.o -obj-$(CONFIG_SHADOW_CALL_STACK) += scs.o obj-$(CONFIG_ARM64_MTE) += mte.o obj-y += vdso/ probes/ diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index b295fb912b12..5c2ac4b5b2da 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -441,7 +441,7 @@ SYM_CODE_END(__swpan_exit_el0) #ifdef CONFIG_SHADOW_CALL_STACK /* also switch to the irq shadow stack */ - adr_this_cpu scs_sp, irq_shadow_call_stack, x26 + ldr_this_cpu scs_sp, irq_shadow_call_stack_ptr, x26 #endif 9998: @@ -1097,9 +1097,9 @@ SYM_CODE_START(__sdei_asm_handler) #ifdef CONFIG_SHADOW_CALL_STACK /* Use a separate shadow call stack for normal and critical events */ cbnz w4, 3f - adr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal, tmp=x6 + ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal_ptr, tmp=x6 b 4f -3: adr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical, tmp=x6 +3: ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical_ptr, tmp=x6 4: #endif diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c index 9cf2fb87584a..5b7ada9d9559 100644 --- a/arch/arm64/kernel/irq.c +++ b/arch/arm64/kernel/irq.c @@ -17,6 +17,7 @@ #include <linux/init.h> #include <linux/irqchip.h> #include <linux/kprobes.h> +#include <linux/scs.h> #include <linux/seq_file.h> #include <linux/vmalloc.h> #include <asm/daifflags.h> @@ -27,6 +28,22 @@ DEFINE_PER_CPU(struct nmi_ctx, nmi_contexts); DEFINE_PER_CPU(unsigned long *, irq_stack_ptr); + +DECLARE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr); + +#ifdef CONFIG_SHADOW_CALL_STACK +DEFINE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr); +#endif + +static void init_irq_scs(void) +{ + int cpu; + + for_each_possible_cpu(cpu) + per_cpu(irq_shadow_call_stack_ptr, cpu) = + scs_alloc(cpu_to_node(cpu)); +} + #ifdef CONFIG_VMAP_STACK static void init_irq_stacks(void) { @@ -54,6 +71,8 @@ static void init_irq_stacks(void) void __init init_IRQ(void) { init_irq_stacks(); + if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) + init_irq_scs(); irqchip_init(); if (!handle_arch_irq) panic("No interrupt controller found."); diff --git a/arch/arm64/kernel/scs.c b/arch/arm64/kernel/scs.c deleted file mode 100644 index e8f7ff45dd8f..000000000000 --- a/arch/arm64/kernel/scs.c +++ /dev/null @@ -1,16 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * Shadow Call Stack support. - * - * Copyright (C) 2019 Google LLC - */ - -#include <linux/percpu.h> -#include <linux/scs.h> - -DEFINE_SCS(irq_shadow_call_stack); - -#ifdef CONFIG_ARM_SDE_INTERFACE -DEFINE_SCS(sdei_shadow_call_stack_normal); -DEFINE_SCS(sdei_shadow_call_stack_critical); -#endif diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c index 7689f2031c0c..cbc370d3bb4f 100644 --- a/arch/arm64/kernel/sdei.c +++ b/arch/arm64/kernel/sdei.c @@ -7,6 +7,7 @@ #include <linux/hardirq.h> #include <linux/irqflags.h> #include <linux/sched/task_stack.h> +#include <linux/scs.h> #include <linux/uaccess.h> #include <asm/alternative.h> @@ -37,6 +38,14 @@ DEFINE_PER_CPU(unsigned long *, sdei_stack_normal_ptr); DEFINE_PER_CPU(unsigned long *, sdei_stack_critical_ptr); #endif +DECLARE_PER_CPU(unsigned long *, sdei_shadow_call_stack_normal_ptr); +DECLARE_PER_CPU(unsigned long *, sdei_shadow_call_stack_critical_ptr); + +#ifdef CONFIG_SHADOW_CALL_STACK +DEFINE_PER_CPU(unsigned long *, sdei_shadow_call_stack_normal_ptr); +DEFINE_PER_CPU(unsigned long *, sdei_shadow_call_stack_critical_ptr); +#endif + static void _free_sdei_stack(unsigned long * __percpu *ptr, int cpu) { unsigned long *p; @@ -48,13 +57,31 @@ static void _free_sdei_stack(unsigned long * __percpu *ptr, int cpu) } } +static void _free_sdei_scs(unsigned long * __percpu *ptr, int cpu) +{ + void *s; + + s = per_cpu(*ptr, cpu); + if (s) { + per_cpu(*ptr, cpu) = NULL; + scs_free(s); + } +} + static void free_sdei_stacks(void) { int cpu; for_each_possible_cpu(cpu) { - _free_sdei_stack(&sdei_stack_normal_ptr, cpu); - _free_sdei_stack(&sdei_stack_critical_ptr, cpu); + if (IS_ENABLED(CONFIG_VMAP_STACK)) { + _free_sdei_stack(&sdei_stack_normal_ptr, cpu); + _free_sdei_stack(&sdei_stack_critical_ptr, cpu); + } + + if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) { + _free_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu); + _free_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu); + } } } @@ -70,18 +97,40 @@ static int _init_sdei_stack(unsigned long * __percpu *ptr, int cpu) return 0; } +static int _init_sdei_scs(unsigned long * __percpu *ptr, int cpu) +{ + void *s; + + s = scs_alloc(cpu_to_node(cpu)); + if (!s) + return -ENOMEM; + per_cpu(*ptr, cpu) = s; + + return 0; +} + static int init_sdei_stacks(void) { int cpu; int err = 0; for_each_possible_cpu(cpu) { - err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu); - if (err) - break; - err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu); - if (err) - break; + if (IS_ENABLED(CONFIG_VMAP_STACK)) { + err = _init_sdei_stack(&sdei_stack_normal_ptr, cpu); + if (err) + break; + err = _init_sdei_stack(&sdei_stack_critical_ptr, cpu); + if (err) + break; + } + if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) { + err = _init_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu); + if (err) + break; + err = _init_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu); + if (err) + break; + } } if (err) @@ -133,10 +182,8 @@ unsigned long sdei_arch_get_entry_point(int conduit) return 0; } - if (IS_ENABLED(CONFIG_VMAP_STACK)) { - if (init_sdei_stacks()) - return 0; - } + if (init_sdei_stacks()) + return 0; sdei_exit_mode = (conduit == SMCCC_CONDUIT_HVC) ? SDEI_EXIT_HVC : SDEI_EXIT_SMC; diff --git a/include/linux/scs.h b/include/linux/scs.h index 2a506c2a16f4..18122d9e17ff 100644 --- a/include/linux/scs.h +++ b/include/linux/scs.h @@ -22,10 +22,6 @@ /* An illegal pointer value to mark the end of the shadow stack. */ #define SCS_END_MAGIC (0x5f6UL + POISON_POINTER_DELTA) -/* Allocate a static per-CPU shadow stack */ -#define DEFINE_SCS(name) \ - DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], name) \ - #define task_scs(tsk) (task_thread_info(tsk)->scs_base) #define task_scs_sp(tsk) (task_thread_info(tsk)->scs_sp)
Use scs_alloc() to allocate also IRQ and SDEI shadow stacks instead of using statically allocated stacks. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> --- arch/arm64/kernel/Makefile | 1 - arch/arm64/kernel/entry.S | 6 ++-- arch/arm64/kernel/irq.c | 19 ++++++++++ arch/arm64/kernel/scs.c | 16 --------- arch/arm64/kernel/sdei.c | 71 +++++++++++++++++++++++++++++++------- include/linux/scs.h | 4 --- 6 files changed, 81 insertions(+), 36 deletions(-) delete mode 100644 arch/arm64/kernel/scs.c