Re: [PATCH] powerpc/64: Implement arch_within_stack_frames

Le 14/12/2022 à 12:48, Christophe Leroy a écrit :

Le 14/12/2022 à 12:39, Nicholas Piggin a écrit :

quoted

On Wed Dec 14, 2022 at 6:39 PM AEST, Christophe Leroy wrote:

quoted

Le 14/12/2022 à 05:42, Nicholas Miehlbradt a écrit :

quoted

Walks the stack when copy_{to,from}_user address is in the stack to
ensure that the object being copied is entirely within a single stack
frame.

Substatially similar to the x86 implementation except using the back
chain to traverse the stack and identify stack frame boundaries.

Signed-off-by: Nicholas Miehlbradt <redacted>
---
   arch/powerpc/Kconfig                   |  1 +
   arch/powerpc/include/asm/thread_info.h | 38 
++++++++++++++++++++++++++
   2 files changed, 39 insertions(+)

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 2ca5418457ed..4c59d139ea83 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig

@@ -198,6 +198,7 @@ config PPC

       select HAVE_ARCH_KASAN_VMALLOC        if HAVE_ARCH_KASAN
       select HAVE_ARCH_KFENCE            if 
ARCH_SUPPORTS_DEBUG_PAGEALLOC
       select HAVE_ARCH_RANDOMIZE_KSTACK_OFFSET
+    select HAVE_ARCH_WITHIN_STACK_FRAMES    if PPC64

Why don't you do something that works for both PPC32 and PPC64 ?

+1

quoted

quoted

       select HAVE_ARCH_KGDB
       select HAVE_ARCH_MMAP_RND_BITS
       select HAVE_ARCH_MMAP_RND_COMPAT_BITS    if COMPAT

diff --git a/arch/powerpc/include/asm/thread_info.h 

b/arch/powerpc/include/asm/thread_info.h
index af58f1ed3952..efdf39e07884 100644

--- a/arch/powerpc/include/asm/thread_info.h
+++ b/arch/powerpc/include/asm/thread_info.h

@@ -186,6 +186,44 @@ static inline bool 

test_thread_local_flags(unsigned int flags)
   #define is_elf2_task() (0)
   #endif
+#ifdef CONFIG_PPC64
+
+#ifdef CONFIG_PPC64_ELF_ABI_V1
+#define PARAMETER_SAVE_OFFSET 48
+#else
+#define PARAMETER_SAVE_OFFSET 32
+#endif

Why not use STACK_INT_FRAME_REGS, defined in asm/ptrace.h ?

I think use a STACK_FRAME prefixed define in asm/ptrace.h, but maybe
avoid overloading the STACK_INT_ stuff for this.

Maybe I should have written _already_ defined :

$ git grep -n STACK_INT_FRAME_REGS arch/powerpc/include/asm/
arch/powerpc/include/asm/ptrace.h:126:#define STACK_INT_FRAME_REGS 
(STACK_FRAME_MIN_SIZE + 16)
arch/powerpc/include/asm/ptrace.h:138:#define STACK_INT_FRAME_REGS 
STACK_FRAME_MIN_SIZE
arch/powerpc/include/asm/ptrace.h:155:#define STACK_INT_FRAME_REGS 
STACK_FRAME_MIN_SIZE

Looks like I misread STACK_FRAME_MIN_SIZE.

So yes, we need a new macro for it.

What about STACK_FRAME_PARAMS ?