Unverified Commit 4c0b5a45 authored by Leonardo Bras's avatar Leonardo Bras Committed by Palmer Dabbelt
Browse files

riscv: add compile-time test into is_compat_task() 



Currently several places will test for CONFIG_COMPAT before testing
is_compat_task(), probably in order to avoid a run-time test into the task
structure.

Since is_compat_task() is an inlined function, it would be helpful to add a
compile-time test of CONFIG_COMPAT, making sure it always returns zero when
the option is not enabled during the kernel build.

With this, the compiler is able to understand in build-time that
is_compat_task() will always return 0, and optimize-out some of the extra
code introduced by the option.

This will also allow removing a lot #ifdefs that were introduced, and make
the code more clean.

Signed-off-by: default avatarLeonardo Bras <leobras@redhat.com>
Reviewed-by: default avatarGuo Ren <guoren@kernel.org>
Reviewed-by: default avatarAndy Chiu <andy.chiu@sifive.com>
Link: https://lore.kernel.org/r/20240103160024.70305-5-leobras@redhat.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 9dc30419

arch/riscv/include/asm/compat.h

+3 −0
Original line number Diff line number Diff line
@@ -14,6 +14,9 @@ 


static inline int is_compat_task(void)

{

	if (!IS_ENABLED(CONFIG_COMPAT))

		return 0;



	return test_thread_flag(TIF_32BIT);

}

arch/riscv/include/asm/elf.h

+0 −4
Original line number Diff line number Diff line
@@ -53,13 +53,9 @@ extern bool compat_elf_check_arch(Elf32_Ehdr *hdr); 
#define ELF_ET_DYN_BASE		((DEFAULT_MAP_WINDOW / 3) * 2)



#ifdef CONFIG_64BIT

#ifdef CONFIG_COMPAT

#define STACK_RND_MASK		(is_compat_task() ? \

				 0x7ff >> (PAGE_SHIFT - 12) : \

				 0x3ffff >> (PAGE_SHIFT - 12))

#else

#define STACK_RND_MASK		(0x3ffff >> (PAGE_SHIFT - 12))

#endif

#endif



/*

arch/riscv/include/asm/pgtable.h

+0 −6
Original line number Diff line number Diff line
@@ -127,16 +127,10 @@ 
#define VA_USER_SV48 (UL(1) << (VA_BITS_SV48 - 1))

#define VA_USER_SV57 (UL(1) << (VA_BITS_SV57 - 1))



#ifdef CONFIG_COMPAT

#define MMAP_VA_BITS_64 ((VA_BITS >= VA_BITS_SV48) ? VA_BITS_SV48 : VA_BITS)

#define MMAP_MIN_VA_BITS_64 (VA_BITS_SV39)

#define MMAP_VA_BITS (is_compat_task() ? VA_BITS_SV32 : MMAP_VA_BITS_64)

#define MMAP_MIN_VA_BITS (is_compat_task() ? VA_BITS_SV32 : MMAP_MIN_VA_BITS_64)

#else

#define MMAP_VA_BITS ((VA_BITS >= VA_BITS_SV48) ? VA_BITS_SV48 : VA_BITS)

#define MMAP_MIN_VA_BITS (VA_BITS_SV39)

#endif /* CONFIG_COMPAT */



#else

#include <asm/pgtable-32.h>

#endif /* CONFIG_64BIT */

arch/riscv/include/asm/processor.h

+2 −2
Original line number Diff line number Diff line
@@ -28,7 +28,7 @@ 
({								\

	unsigned long mmap_end;					\

	typeof(addr) _addr = (addr);				\

	if ((_addr) == 0 || (IS_ENABLED(CONFIG_COMPAT) && is_compat_task())) \

	if ((_addr) == 0 || is_compat_task())			\

		mmap_end = STACK_TOP_MAX;			\

	else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \

		mmap_end = VA_USER_SV57;			\
@@ -45,7 +45,7 @@ 
	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())			\

		mmap_base = (_base);				\

	else if (((_addr) >= VA_USER_SV57) && (VA_BITS >= VA_BITS_SV57)) \

		mmap_base = VA_USER_SV57 - rnd_gap;		\