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Date: Wed, 30 Mar 2022 16:12:18 -0700 (PDT)
From: Palmer Dabbelt <palmer@...belt.com>
To: keescook@...omium.org
CC: Paul Walmsley <paul.walmsley@...ive.com>, keescook@...omium.org,
aou@...s.berkeley.edu, peterz@...radead.org, jszhang@...nel.org,
geert@...ux-m68k.org, mark.rutland@....com, chenhuang5@...wei.com,
linux-riscv@...ts.infradead.org, wangkefeng.wang@...wei.com,
linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] riscv: Rename "sp_in_global" to "current_stack_pointer"
On Tue, 22 Mar 2022 19:16:28 PDT (-0700), Palmer Dabbelt wrote:
> On Wed, 23 Feb 2022 22:04:11 PST (-0800), keescook@...omium.org wrote:
>> To follow the existing per-arch conventions, rename "sp_in_global" to
>> "current_stack_pointer". This will let it be used in non-arch places
>> (like HARDENED_USERCOPY).
>>
>> Cc: Paul Walmsley <paul.walmsley@...ive.com>
>> Cc: Palmer Dabbelt <palmer@...belt.com>
>> Cc: Albert Ou <aou@...s.berkeley.edu>
>> Cc: Peter Zijlstra <peterz@...radead.org>
>> Cc: Jisheng Zhang <jszhang@...nel.org>
>> Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
>> Cc: Mark Rutland <mark.rutland@....com>
>> Cc: Chen Huang <chenhuang5@...wei.com>
>> Cc: linux-riscv@...ts.infradead.org
>> Signed-off-by: Kees Cook <keescook@...omium.org>
>> ---
>> arch/riscv/Kconfig | 1 +
>> arch/riscv/include/asm/current.h | 2 ++
>> arch/riscv/kernel/stacktrace.c | 4 +---
>> 3 files changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index 5adcbd9b5e88..b120c32697af 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -16,6 +16,7 @@ config RISCV
>> select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
>> select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
>> select ARCH_HAS_BINFMT_FLAT
>> + select ARCH_HAS_CURRENT_STACK_POINTER
>> select ARCH_HAS_DEBUG_VM_PGTABLE
>> select ARCH_HAS_DEBUG_VIRTUAL if MMU
>> select ARCH_HAS_DEBUG_WX
>> diff --git a/arch/riscv/include/asm/current.h b/arch/riscv/include/asm/current.h
>> index 1de233d8e8de..21774d868c65 100644
>> --- a/arch/riscv/include/asm/current.h
>> +++ b/arch/riscv/include/asm/current.h
>> @@ -33,6 +33,8 @@ static __always_inline struct task_struct *get_current(void)
>>
>> #define current get_current()
>>
>> +register unsigned long current_stack_pointer __asm__("sp");
>> +
>> #endif /* __ASSEMBLY__ */
>>
>> #endif /* _ASM_RISCV_CURRENT_H */
>> diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
>> index 201ee206fb57..278380e2e956 100644
>> --- a/arch/riscv/kernel/stacktrace.c
>> +++ b/arch/riscv/kernel/stacktrace.c
>> @@ -14,8 +14,6 @@
>>
>> #include <asm/stacktrace.h>
>>
>> -register unsigned long sp_in_global __asm__("sp");
>> -
>> #ifdef CONFIG_FRAME_POINTER
>>
>> void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
>> @@ -77,7 +75,7 @@ void notrace walk_stackframe(struct task_struct *task,
>> sp = user_stack_pointer(regs);
>> pc = instruction_pointer(regs);
>> } else if (task == NULL || task == current) {
>> - sp = sp_in_global;
>> + sp = current_stack_pointer;
>> pc = (unsigned long)walk_stackframe;
>> } else {
>> /* task blocked in __switch_to */
>
> Sorry to be slow on this one. This looks good, but another use of
> sp_in_global snuck into fixes and I don't merge fixes into for-next so
> that makes this a bit of a headache.
>
> There's a bunch of stuff in flight, so I'm going to hold off on this
> until after my first week's merge window PR. I intend on merging the
> following, which is at palmer/riscv-sp for now (I'll probably just
> cherry-pick that, I usually start basing stuff on Linus' merge of my PR
> and just cherry-pick in single patches).
>
> commit 7c4f6bb6fb352cfa6028191c2888356b9157a332
> gpg: Signature made Tue 22 Mar 2022 11:12:19 AM PDT
> gpg: using RSA key 2B3C3747446843B24A943A7A2E1319F35FBB1889
> gpg: issuer "palmer@...belt.com"
> gpg: Good signature from "Palmer Dabbelt <palmer@...belt.com>" [ultimate]
> gpg: aka "Palmer Dabbelt <palmer@...osinc.com>" [ultimate]
> Author: Kees Cook <keescook@...omium.org>
> Date: Wed Feb 23 22:04:11 2022 -0800
>
> riscv: Rename "sp_in_global" to "current_stack_pointer"
>
> To follow the existing per-arch conventions, rename "sp_in_global" to
> "current_stack_pointer". This will let it be used in non-arch places
> (like HARDENED_USERCOPY).
>
> Signed-off-by: Kees Cook <keescook@...omium.org>
> Signed-off-by: Palmer Dabbelt <palmer@...osinc.com>
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 5adcbd9b5e88..b120c32697af 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -16,6 +16,7 @@ config RISCV
> select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
> select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
> select ARCH_HAS_BINFMT_FLAT
> + select ARCH_HAS_CURRENT_STACK_POINTER
> select ARCH_HAS_DEBUG_VM_PGTABLE
> select ARCH_HAS_DEBUG_VIRTUAL if MMU
> select ARCH_HAS_DEBUG_WX
> diff --git a/arch/riscv/include/asm/current.h b/arch/riscv/include/asm/current.h
> index 1de233d8e8de..21774d868c65 100644
> --- a/arch/riscv/include/asm/current.h
> +++ b/arch/riscv/include/asm/current.h
> @@ -33,6 +33,8 @@ static __always_inline struct task_struct *get_current(void)
>
> #define current get_current()
>
> +register unsigned long current_stack_pointer __asm__("sp");
> +
> #endif /* __ASSEMBLY__ */
>
> #endif /* _ASM_RISCV_CURRENT_H */
> diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
> index 14d2b53ec322..08d11a53f39e 100644
> --- a/arch/riscv/kernel/stacktrace.c
> +++ b/arch/riscv/kernel/stacktrace.c
> @@ -14,8 +14,6 @@
>
> #include <asm/stacktrace.h>
>
> -register unsigned long sp_in_global __asm__("sp");
> -
> #ifdef CONFIG_FRAME_POINTER
>
> void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
> @@ -30,7 +28,7 @@ void notrace walk_stackframe(struct task_struct *task, struct pt_regs *regs,
> pc = instruction_pointer(regs);
> } else if (task == NULL || task == current) {
> fp = (unsigned long)__builtin_frame_address(0);
> - sp = sp_in_global;
> + sp = current_stack_pointer;
> pc = (unsigned long)walk_stackframe;
> } else {
> /* task blocked in __switch_to */
> @@ -78,7 +76,7 @@ void notrace walk_stackframe(struct task_struct *task,
> sp = user_stack_pointer(regs);
> pc = instruction_pointer(regs);
> } else if (task == NULL || task == current) {
> - sp = sp_in_global;
> + sp = current_stack_pointer;
> pc = (unsigned long)walk_stackframe;
> } else {
> /* task blocked in __switch_to */
>
> Thanks!
Thanks, this is on for-next. I put HARDENED_USERCOPY=y test in for SLAB
and SLUB, not sure if there's anything else that's interesting to test
(we're missing some bits needed for STACKLEAK).
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