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

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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>
This commit is contained in:
Palmer Dabbelt 2024-03-19 17:09:05 -07:00
commit 728e7ea2b5
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GPG Key ID: 2E1319F35FBB1889
5 changed files with 34 additions and 24 deletions
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19
arch/riscv/include/asm/compat.h
View File

@ -14,9 +14,28 @@
static inline int is_compat_task(void)
{
if (!IS_ENABLED(CONFIG_COMPAT))
return 0;
return test_thread_flag(TIF_32BIT);
}
static inline int is_compat_thread(struct thread_info *thread)
{
if (!IS_ENABLED(CONFIG_COMPAT))
return 0;
return test_ti_thread_flag(thread, TIF_32BIT);
}
static inline void set_compat_task(bool is_compat)
{
if (is_compat)
set_thread_flag(TIF_32BIT);
else
clear_thread_flag(TIF_32BIT);
}
struct compat_user_regs_struct {
compat_ulong_t pc;
compat_ulong_t ra;

11
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 (test_thread_flag(TIF_32BIT) ? \
#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
/*
@ -139,10 +135,7 @@ do { \
#ifdef CONFIG_COMPAT
#define SET_PERSONALITY(ex) \
do { if ((ex).e_ident[EI_CLASS] == ELFCLASS32) \
set_thread_flag(TIF_32BIT); \
else \
clear_thread_flag(TIF_32BIT); \
do { set_compat_task((ex).e_ident[EI_CLASS] == ELFCLASS32); \
if (personality(current->personality) != PER_LINUX32) \
set_personality(PER_LINUX | \
(current->personality & (~PER_MASK))); \

10
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 */
@ -877,8 +871,8 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
#define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
#ifdef CONFIG_COMPAT
#define TASK_SIZE_32 (_AC(0x80000000, UL))
#define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
#define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE)
#define TASK_SIZE (is_compat_task() ? \
TASK_SIZE_32 : TASK_SIZE_64)
#else
#define TASK_SIZE TASK_SIZE_64

12
arch/riscv/include/asm/processor.h
View File

@ -14,12 +14,17 @@
#include <asm/ptrace.h>
/*
* 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() || \
((_addr + len) > BIT(VA_BITS - 1))) \
mmap_end = STACK_TOP_MAX; \
else \
@ -33,8 +38,7 @@
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() || \
((_addr + len) > BIT(VA_BITS - 1))) \
mmap_base = (_base); \
else \

6
arch/riscv/kernel/ptrace.c
View File

@ -377,14 +377,14 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
return ret;
}
#else
static const struct user_regset_view compat_riscv_user_native_view = {};
#endif /* CONFIG_COMPAT */
const struct user_regset_view *task_user_regset_view(struct task_struct *task)
{
#ifdef CONFIG_COMPAT
if (test_tsk_thread_flag(task, TIF_32BIT))
if (is_compat_thread(&task->thread_info))
return &compat_riscv_user_native_view;
else
#endif
return &riscv_user_native_view;
}