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SubjectRe: [PATCH] riscv: Rename "sp_in_global" to "current_stack_pointer"
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On Wed, 23 Feb 2022 22:04:11 PST (-0800), keescook@chromium.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@sifive.com>
> Cc: Palmer Dabbelt <palmer@dabbelt.com>
> Cc: Albert Ou <aou@eecs.berkeley.edu>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Jisheng Zhang <jszhang@kernel.org>
> Cc: Geert Uytterhoeven <geert@linux-m68k.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Chen Huang <chenhuang5@huawei.com>
> Cc: linux-riscv@lists.infradead.org
> Signed-off-by: Kees Cook <keescook@chromium.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@dabbelt.com"
gpg: Good signature from "Palmer Dabbelt <palmer@dabbelt.com>" [ultimate]
gpg: aka "Palmer Dabbelt <palmer@rivosinc.com>" [ultimate]
Author: Kees Cook <keescook@chromium.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@chromium.org>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.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!

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