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riscv: add compile-time test into is_compat_task()

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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: Leonardo Bras <leobras@redhat.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Reviewed-by: Andy Chiu <andy.chiu@sifive.com>
Link: https://lore.kernel.org/r/20240103160024.70305-5-leobras@redhat.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Leonardo Bras 2024-01-03 13:00:21 -03:00 committed by Palmer Dabbelt
parent 9dc3041924
commit 4c0b5a4516
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GPG Key ID: 2E1319F35FBB1889
4 changed files with 5 additions and 12 deletions
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3
arch/riscv/include/asm/compat.h
View File

@ -14,6 +14,9 @@
static inline int is_compat_task(void)
{
if (!IS_ENABLED(CONFIG_COMPAT))
return 0;
return test_thread_flag(TIF_32BIT);
}

4
arch/riscv/include/asm/elf.h
View File

@ -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
/*

6
arch/riscv/include/asm/pgtable.h
View File

@ -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 */

4
arch/riscv/include/asm/processor.h
View File

@ -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; \