Messages in this thread | | | Date | Tue, 1 Dec 2020 10:18:19 +0000 | From | Will Deacon <> | Subject | Re: [PATCH v2 2/2] arm64: scs: use vmapped IRQ and SDEI shadow stacks |
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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
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