From: Jisheng Zhang <jszhang@kernel.org> To: Palmer Dabbelt <palmer@rivosinc.com> Cc: guoren@kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] RISC-V: Add some comments about the shadow and overflow stacks Date: Fri, 2 Dec 2022 00:21:55 +0800 [thread overview] Message-ID: <Y4jUo09vh7PudmXW@xhacker> (raw) In-Reply-To: <20221130023515.20217-2-palmer@rivosinc.com> On Tue, Nov 29, 2022 at 06:35:15PM -0800, Palmer Dabbelt wrote: > It took me a while to page all this back in when trying to review the > recent spin_shadow_stack, so I figured I'd just write up some comments. > > Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> Reviewed-by: Jisheng Zhang <jszhang@kernel.org> > --- > arch/riscv/kernel/traps.c | 20 +++++++++++++------- > 1 file changed, 13 insertions(+), 7 deletions(-) > > diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c > index acdfcacd7e57..336d4aadadb1 100644 > --- a/arch/riscv/kernel/traps.c > +++ b/arch/riscv/kernel/traps.c > @@ -200,18 +200,18 @@ void __init trap_init(void) > } > > #ifdef CONFIG_VMAP_STACK > +/* > + * Extra stack space that allows us to provide panic messages when the kernel > + * has overflowed its stack. > + */ > static DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], > overflow_stack)__aligned(16); > /* > - * shadow stack, handled_ kernel_ stack_ overflow(in kernel/entry.S) is used > - * to get per-cpu overflow stack(get_overflow_stack). > + * A temporary stack for use by handle_kernel_stack_overflow. This is used so > + * we can call into C code to get the per-hart overflow stack. Usage of this > + * stack must be protected by spin_shadow_stack. > */ > long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE/sizeof(long)] __aligned(16); > -asmlinkage unsigned long get_overflow_stack(void) > -{ > - return (unsigned long)this_cpu_ptr(overflow_stack) + > - OVERFLOW_STACK_SIZE; > -} > > /* > * A pseudo spinlock to protect the shadow stack from being used by multiple > @@ -222,6 +222,12 @@ asmlinkage unsigned long get_overflow_stack(void) > */ > unsigned long spin_shadow_stack; > > +asmlinkage unsigned long get_overflow_stack(void) > +{ > + return (unsigned long)this_cpu_ptr(overflow_stack) + > + OVERFLOW_STACK_SIZE; > +} > + > asmlinkage void handle_bad_stack(struct pt_regs *regs) > { > unsigned long tsk_stk = (unsigned long)current->stack; > -- > 2.38.1 >
WARNING: multiple messages have this Message-ID (diff)
From: Jisheng Zhang <jszhang@kernel.org> To: Palmer Dabbelt <palmer@rivosinc.com> Cc: guoren@kernel.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] RISC-V: Add some comments about the shadow and overflow stacks Date: Fri, 2 Dec 2022 00:21:55 +0800 [thread overview] Message-ID: <Y4jUo09vh7PudmXW@xhacker> (raw) In-Reply-To: <20221130023515.20217-2-palmer@rivosinc.com> On Tue, Nov 29, 2022 at 06:35:15PM -0800, Palmer Dabbelt wrote: > It took me a while to page all this back in when trying to review the > recent spin_shadow_stack, so I figured I'd just write up some comments. > > Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> Reviewed-by: Jisheng Zhang <jszhang@kernel.org> > --- > arch/riscv/kernel/traps.c | 20 +++++++++++++------- > 1 file changed, 13 insertions(+), 7 deletions(-) > > diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c > index acdfcacd7e57..336d4aadadb1 100644 > --- a/arch/riscv/kernel/traps.c > +++ b/arch/riscv/kernel/traps.c > @@ -200,18 +200,18 @@ void __init trap_init(void) > } > > #ifdef CONFIG_VMAP_STACK > +/* > + * Extra stack space that allows us to provide panic messages when the kernel > + * has overflowed its stack. > + */ > static DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], > overflow_stack)__aligned(16); > /* > - * shadow stack, handled_ kernel_ stack_ overflow(in kernel/entry.S) is used > - * to get per-cpu overflow stack(get_overflow_stack). > + * A temporary stack for use by handle_kernel_stack_overflow. This is used so > + * we can call into C code to get the per-hart overflow stack. Usage of this > + * stack must be protected by spin_shadow_stack. > */ > long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE/sizeof(long)] __aligned(16); > -asmlinkage unsigned long get_overflow_stack(void) > -{ > - return (unsigned long)this_cpu_ptr(overflow_stack) + > - OVERFLOW_STACK_SIZE; > -} > > /* > * A pseudo spinlock to protect the shadow stack from being used by multiple > @@ -222,6 +222,12 @@ asmlinkage unsigned long get_overflow_stack(void) > */ > unsigned long spin_shadow_stack; > > +asmlinkage unsigned long get_overflow_stack(void) > +{ > + return (unsigned long)this_cpu_ptr(overflow_stack) + > + OVERFLOW_STACK_SIZE; > +} > + > asmlinkage void handle_bad_stack(struct pt_regs *regs) > { > unsigned long tsk_stk = (unsigned long)current->stack; > -- > 2.38.1 > _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next prev parent reply other threads:[~2022-12-01 16:32 UTC|newest] Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-11-30 2:35 [PATCH 1/2] RISC-V: Align the shadow stack Palmer Dabbelt 2022-11-30 2:35 ` Palmer Dabbelt 2022-11-30 2:35 ` [PATCH 2/2] RISC-V: Add some comments about the shadow and overflow stacks Palmer Dabbelt 2022-11-30 2:35 ` Palmer Dabbelt 2022-12-01 13:17 ` Guo Ren 2022-12-01 13:17 ` Guo Ren 2022-12-01 16:21 ` Jisheng Zhang [this message] 2022-12-01 16:21 ` Jisheng Zhang 2022-11-30 2:47 ` [PATCH 1/2] RISC-V: Align the shadow stack Khem Raj 2022-11-30 2:47 ` Khem Raj 2022-11-30 2:50 ` Palmer Dabbelt 2022-11-30 2:50 ` Palmer Dabbelt 2022-11-30 2:56 ` Khem Raj 2022-11-30 2:56 ` Khem Raj 2022-11-30 3:00 ` Palmer Dabbelt 2022-11-30 3:00 ` Palmer Dabbelt 2022-12-01 16:22 ` Jisheng Zhang 2022-12-01 16:22 ` Jisheng Zhang 2022-12-13 6:17 ` Palmer Dabbelt 2022-12-13 6:17 ` Palmer Dabbelt 2022-12-13 6:20 ` patchwork-bot+linux-riscv 2022-12-13 6:20 ` patchwork-bot+linux-riscv
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