From: Palmer Dabbelt <palmer@rivosinc.com>
Date: Wed, 20 Mar 2024 00:09:05 +0000 (-0700)
Subject: Merge patch series "riscv: Introduce compat-mode helpers & improve arch_get_mmap_end()"
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=728e7ea2b56d0eba5a3c952e6c613523160723c8;p=linux.git

Merge patch series "riscv: Introduce compat-mode helpers & improve arch_get_mmap_end()"

Leonardo Bras <leobras@redhat.com> says:

I just saw the opportunity of optimizing the helper is_compat_task() by
introducing a compile-time test, and it made possible to remove some
 #ifdef's without any loss of performance.

I also saw the possibility of removing the direct check of task flags from
general code, and concentrated it in asm/compat.h by creating a few more
helpers, which in the end helped optimize code.

arch_get_mmap_end() just got a simple improvement and some extra docs.

* b4-shazam-merge:
  riscv: Introduce set_compat_task() in asm/compat.h
  riscv: Introduce is_compat_thread() into compat.h
  riscv: add compile-time test into is_compat_task()
  riscv: Replace direct thread flag check with is_compat_task()
  riscv: Improve arch_get_mmap_end() macro

Link: https://lore.kernel.org/r/20240103160024.70305-2-leobras@redhat.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
---

728e7ea2b56d0eba5a3c952e6c613523160723c8
diff --cc arch/riscv/include/asm/processor.h
index 0d13b4497b017,d2d7ce30baf3e..0faf5f161f1e4
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@@ -14,16 -14,28 +14,21 @@@
  
  #include <asm/ptrace.h>
  
 -#ifdef CONFIG_64BIT
 -#define DEFAULT_MAP_WINDOW	(UL(1) << (MMAP_VA_BITS - 1))
 -#define STACK_TOP_MAX		TASK_SIZE_64
 -
+ /*
+  * addr is a hint to the maximum userspace address that mmap should provide, so
+  * this macro needs to return the largest address space available so that
+  * mmap_end < addr, being mmap_end the top of that address space.
+  * See Documentation/arch/riscv/vm-layout.rst for more details.
+  */
  #define arch_get_mmap_end(addr, len, flags)			\
  ({								\
  	unsigned long mmap_end;					\
  	typeof(addr) _addr = (addr);				\
- 	if ((_addr) == 0 ||					\
- 	    (IS_ENABLED(CONFIG_COMPAT) && is_compat_task()) ||	\
 -	if ((_addr) == 0 || is_compat_task())			\
++	if ((_addr) == 0 || is_compat_task() ||			\
 +	    ((_addr + len) > BIT(VA_BITS - 1)))			\
  		mmap_end = STACK_TOP_MAX;			\
 -	else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \
 -		mmap_end = VA_USER_SV57;			\
 -	else if (((_addr) >= VA_USER_SV48) && (VA_BITS >= VA_BITS_SV48)) \
 -		mmap_end = VA_USER_SV48;			\
  	else							\
 -		mmap_end = VA_USER_SV39;			\
 +		mmap_end = (_addr + len);			\
  	mmap_end;						\
  })
  
@@@ -33,12 -45,14 +38,11 @@@
  	typeof(addr) _addr = (addr);				\
  	typeof(base) _base = (base);				\
  	unsigned long rnd_gap = DEFAULT_MAP_WINDOW - (_base);	\
- 	if ((_addr) == 0 ||					\
- 	    (IS_ENABLED(CONFIG_COMPAT) && is_compat_task()) ||	\
 -	if ((_addr) == 0 || is_compat_task())			\
++	if ((_addr) == 0 || is_compat_task() || 		\
 +	    ((_addr + len) > BIT(VA_BITS - 1)))			\
  		mmap_base = (_base);				\
 -	else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \
 -		mmap_base = VA_USER_SV57 - rnd_gap;		\
 -	else if ((((_addr) >= VA_USER_SV48)) && (VA_BITS >= VA_BITS_SV48)) \
 -		mmap_base = VA_USER_SV48 - rnd_gap;		\
  	else							\
 -		mmap_base = VA_USER_SV39 - rnd_gap;		\
 +		mmap_base = (_addr + len) - rnd_gap;		\
  	mmap_base;						\
  })