From: Mateusz Guzik <mjguzik@gmail.com>
To: torvalds@linux-foundation.org
Cc: brauner@kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
tglx@linutronix.de, pfalcato@suse.de,
Mateusz Guzik <mjguzik@gmail.com>
Subject: [PATCH 2/3] runtime-const: split headers between accessors and fixup; disable for modules
Date: Fri, 31 Oct 2025 18:42:19 +0100 [thread overview]
Message-ID: <20251031174220.43458-3-mjguzik@gmail.com> (raw)
In-Reply-To: <20251031174220.43458-1-mjguzik@gmail.com>
risv and x86 covered as a POC
---
.../include/asm/runtime-const-accessors.h | 151 ++++++++++++++++++
arch/riscv/include/asm/runtime-const.h | 142 +---------------
.../x86/include/asm/runtime-const-accessors.h | 45 ++++++
arch/x86/include/asm/runtime-const.h | 38 +----
4 files changed, 200 insertions(+), 176 deletions(-)
create mode 100644 arch/riscv/include/asm/runtime-const-accessors.h
create mode 100644 arch/x86/include/asm/runtime-const-accessors.h
diff --git a/arch/riscv/include/asm/runtime-const-accessors.h b/arch/riscv/include/asm/runtime-const-accessors.h
new file mode 100644
index 000000000000..5b8e0349ee0d
--- /dev/null
+++ b/arch/riscv/include/asm/runtime-const-accessors.h
@@ -0,0 +1,151 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RISCV_RUNTIME_CONST_ACCESSORS_H
+#define _ASM_RISCV_RUNTIME_CONST_ACCESSORS_H
+
+#ifdef MODULE
+#error "this functionality is not available for modules"
+#endif
+
+#ifdef CONFIG_32BIT
+#define runtime_const_ptr(sym) \
+({ \
+ typeof(sym) __ret; \
+ asm_inline(".option push\n\t" \
+ ".option norvc\n\t" \
+ "1:\t" \
+ "lui %[__ret],0x89abd\n\t" \
+ "addi %[__ret],%[__ret],-0x211\n\t" \
+ ".option pop\n\t" \
+ ".pushsection runtime_ptr_" #sym ",\"a\"\n\t" \
+ ".long 1b - .\n\t" \
+ ".popsection" \
+ : [__ret] "=r" (__ret)); \
+ __ret; \
+})
+#else
+/*
+ * Loading 64-bit constants into a register from immediates is a non-trivial
+ * task on riscv64. To get it somewhat performant, load 32 bits into two
+ * different registers and then combine the results.
+ *
+ * If the processor supports the Zbkb extension, we can combine the final
+ * "slli,slli,srli,add" into the single "pack" instruction. If the processor
+ * doesn't support Zbkb but does support the Zbb extension, we can
+ * combine the final "slli,srli,add" into one instruction "add.uw".
+ */
+#define RISCV_RUNTIME_CONST_64_PREAMBLE \
+ ".option push\n\t" \
+ ".option norvc\n\t" \
+ "1:\t" \
+ "lui %[__ret],0x89abd\n\t" \
+ "lui %[__tmp],0x1234\n\t" \
+ "addiw %[__ret],%[__ret],-0x211\n\t" \
+ "addiw %[__tmp],%[__tmp],0x567\n\t" \
+
+#define RISCV_RUNTIME_CONST_64_BASE \
+ "slli %[__tmp],%[__tmp],32\n\t" \
+ "slli %[__ret],%[__ret],32\n\t" \
+ "srli %[__ret],%[__ret],32\n\t" \
+ "add %[__ret],%[__ret],%[__tmp]\n\t" \
+
+#define RISCV_RUNTIME_CONST_64_ZBA \
+ ".option push\n\t" \
+ ".option arch,+zba\n\t" \
+ ".option norvc\n\t" \
+ "slli %[__tmp],%[__tmp],32\n\t" \
+ "add.uw %[__ret],%[__ret],%[__tmp]\n\t" \
+ "nop\n\t" \
+ "nop\n\t" \
+ ".option pop\n\t" \
+
+#define RISCV_RUNTIME_CONST_64_ZBKB \
+ ".option push\n\t" \
+ ".option arch,+zbkb\n\t" \
+ ".option norvc\n\t" \
+ "pack %[__ret],%[__ret],%[__tmp]\n\t" \
+ "nop\n\t" \
+ "nop\n\t" \
+ "nop\n\t" \
+ ".option pop\n\t" \
+
+#define RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
+ ".option pop\n\t" \
+ ".pushsection runtime_ptr_" #sym ",\"a\"\n\t" \
+ ".long 1b - .\n\t" \
+ ".popsection" \
+
+#if defined(CONFIG_RISCV_ISA_ZBA) && defined(CONFIG_TOOLCHAIN_HAS_ZBA) \
+ && defined(CONFIG_RISCV_ISA_ZBKB)
+#define runtime_const_ptr(sym) \
+({ \
+ typeof(sym) __ret, __tmp; \
+ asm_inline(RISCV_RUNTIME_CONST_64_PREAMBLE \
+ ALTERNATIVE_2( \
+ RISCV_RUNTIME_CONST_64_BASE, \
+ RISCV_RUNTIME_CONST_64_ZBA, \
+ 0, RISCV_ISA_EXT_ZBA, 1, \
+ RISCV_RUNTIME_CONST_64_ZBKB, \
+ 0, RISCV_ISA_EXT_ZBKB, 1 \
+ ) \
+ RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
+ : [__ret] "=r" (__ret), [__tmp] "=r" (__tmp)); \
+ __ret; \
+})
+#elif defined(CONFIG_RISCV_ISA_ZBA) && defined(CONFIG_TOOLCHAIN_HAS_ZBA)
+#define runtime_const_ptr(sym) \
+({ \
+ typeof(sym) __ret, __tmp; \
+ asm_inline(RISCV_RUNTIME_CONST_64_PREAMBLE \
+ ALTERNATIVE( \
+ RISCV_RUNTIME_CONST_64_BASE, \
+ RISCV_RUNTIME_CONST_64_ZBA, \
+ 0, RISCV_ISA_EXT_ZBA, 1 \
+ ) \
+ RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
+ : [__ret] "=r" (__ret), [__tmp] "=r" (__tmp)); \
+ __ret; \
+})
+#elif defined(CONFIG_RISCV_ISA_ZBKB)
+#define runtime_const_ptr(sym) \
+({ \
+ typeof(sym) __ret, __tmp; \
+ asm_inline(RISCV_RUNTIME_CONST_64_PREAMBLE \
+ ALTERNATIVE( \
+ RISCV_RUNTIME_CONST_64_BASE, \
+ RISCV_RUNTIME_CONST_64_ZBKB, \
+ 0, RISCV_ISA_EXT_ZBKB, 1 \
+ ) \
+ RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
+ : [__ret] "=r" (__ret), [__tmp] "=r" (__tmp)); \
+ __ret; \
+})
+#else
+#define runtime_const_ptr(sym) \
+({ \
+ typeof(sym) __ret, __tmp; \
+ asm_inline(RISCV_RUNTIME_CONST_64_PREAMBLE \
+ RISCV_RUNTIME_CONST_64_BASE \
+ RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
+ : [__ret] "=r" (__ret), [__tmp] "=r" (__tmp)); \
+ __ret; \
+})
+#endif
+#endif
+
+#define runtime_const_shift_right_32(val, sym) \
+({ \
+ u32 __ret; \
+ asm_inline(".option push\n\t" \
+ ".option norvc\n\t" \
+ "1:\t" \
+ SRLI " %[__ret],%[__val],12\n\t" \
+ ".option pop\n\t" \
+ ".pushsection runtime_shift_" #sym ",\"a\"\n\t" \
+ ".long 1b - .\n\t" \
+ ".popsection" \
+ : [__ret] "=r" (__ret) \
+ : [__val] "r" (val)); \
+ __ret; \
+})
+
+#endif /* _ASM_RISCV_RUNTIME_CONST_ACCESSORS_H */
diff --git a/arch/riscv/include/asm/runtime-const.h b/arch/riscv/include/asm/runtime-const.h
index d766e2b9e6df..14994be81487 100644
--- a/arch/riscv/include/asm/runtime-const.h
+++ b/arch/riscv/include/asm/runtime-const.h
@@ -11,147 +11,7 @@
#include <linux/uaccess.h>
-#ifdef CONFIG_32BIT
-#define runtime_const_ptr(sym) \
-({ \
- typeof(sym) __ret; \
- asm_inline(".option push\n\t" \
- ".option norvc\n\t" \
- "1:\t" \
- "lui %[__ret],0x89abd\n\t" \
- "addi %[__ret],%[__ret],-0x211\n\t" \
- ".option pop\n\t" \
- ".pushsection runtime_ptr_" #sym ",\"a\"\n\t" \
- ".long 1b - .\n\t" \
- ".popsection" \
- : [__ret] "=r" (__ret)); \
- __ret; \
-})
-#else
-/*
- * Loading 64-bit constants into a register from immediates is a non-trivial
- * task on riscv64. To get it somewhat performant, load 32 bits into two
- * different registers and then combine the results.
- *
- * If the processor supports the Zbkb extension, we can combine the final
- * "slli,slli,srli,add" into the single "pack" instruction. If the processor
- * doesn't support Zbkb but does support the Zbb extension, we can
- * combine the final "slli,srli,add" into one instruction "add.uw".
- */
-#define RISCV_RUNTIME_CONST_64_PREAMBLE \
- ".option push\n\t" \
- ".option norvc\n\t" \
- "1:\t" \
- "lui %[__ret],0x89abd\n\t" \
- "lui %[__tmp],0x1234\n\t" \
- "addiw %[__ret],%[__ret],-0x211\n\t" \
- "addiw %[__tmp],%[__tmp],0x567\n\t" \
-
-#define RISCV_RUNTIME_CONST_64_BASE \
- "slli %[__tmp],%[__tmp],32\n\t" \
- "slli %[__ret],%[__ret],32\n\t" \
- "srli %[__ret],%[__ret],32\n\t" \
- "add %[__ret],%[__ret],%[__tmp]\n\t" \
-
-#define RISCV_RUNTIME_CONST_64_ZBA \
- ".option push\n\t" \
- ".option arch,+zba\n\t" \
- ".option norvc\n\t" \
- "slli %[__tmp],%[__tmp],32\n\t" \
- "add.uw %[__ret],%[__ret],%[__tmp]\n\t" \
- "nop\n\t" \
- "nop\n\t" \
- ".option pop\n\t" \
-
-#define RISCV_RUNTIME_CONST_64_ZBKB \
- ".option push\n\t" \
- ".option arch,+zbkb\n\t" \
- ".option norvc\n\t" \
- "pack %[__ret],%[__ret],%[__tmp]\n\t" \
- "nop\n\t" \
- "nop\n\t" \
- "nop\n\t" \
- ".option pop\n\t" \
-
-#define RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
- ".option pop\n\t" \
- ".pushsection runtime_ptr_" #sym ",\"a\"\n\t" \
- ".long 1b - .\n\t" \
- ".popsection" \
-
-#if defined(CONFIG_RISCV_ISA_ZBA) && defined(CONFIG_TOOLCHAIN_HAS_ZBA) \
- && defined(CONFIG_RISCV_ISA_ZBKB)
-#define runtime_const_ptr(sym) \
-({ \
- typeof(sym) __ret, __tmp; \
- asm_inline(RISCV_RUNTIME_CONST_64_PREAMBLE \
- ALTERNATIVE_2( \
- RISCV_RUNTIME_CONST_64_BASE, \
- RISCV_RUNTIME_CONST_64_ZBA, \
- 0, RISCV_ISA_EXT_ZBA, 1, \
- RISCV_RUNTIME_CONST_64_ZBKB, \
- 0, RISCV_ISA_EXT_ZBKB, 1 \
- ) \
- RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
- : [__ret] "=r" (__ret), [__tmp] "=r" (__tmp)); \
- __ret; \
-})
-#elif defined(CONFIG_RISCV_ISA_ZBA) && defined(CONFIG_TOOLCHAIN_HAS_ZBA)
-#define runtime_const_ptr(sym) \
-({ \
- typeof(sym) __ret, __tmp; \
- asm_inline(RISCV_RUNTIME_CONST_64_PREAMBLE \
- ALTERNATIVE( \
- RISCV_RUNTIME_CONST_64_BASE, \
- RISCV_RUNTIME_CONST_64_ZBA, \
- 0, RISCV_ISA_EXT_ZBA, 1 \
- ) \
- RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
- : [__ret] "=r" (__ret), [__tmp] "=r" (__tmp)); \
- __ret; \
-})
-#elif defined(CONFIG_RISCV_ISA_ZBKB)
-#define runtime_const_ptr(sym) \
-({ \
- typeof(sym) __ret, __tmp; \
- asm_inline(RISCV_RUNTIME_CONST_64_PREAMBLE \
- ALTERNATIVE( \
- RISCV_RUNTIME_CONST_64_BASE, \
- RISCV_RUNTIME_CONST_64_ZBKB, \
- 0, RISCV_ISA_EXT_ZBKB, 1 \
- ) \
- RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
- : [__ret] "=r" (__ret), [__tmp] "=r" (__tmp)); \
- __ret; \
-})
-#else
-#define runtime_const_ptr(sym) \
-({ \
- typeof(sym) __ret, __tmp; \
- asm_inline(RISCV_RUNTIME_CONST_64_PREAMBLE \
- RISCV_RUNTIME_CONST_64_BASE \
- RISCV_RUNTIME_CONST_64_POSTAMBLE(sym) \
- : [__ret] "=r" (__ret), [__tmp] "=r" (__tmp)); \
- __ret; \
-})
-#endif
-#endif
-
-#define runtime_const_shift_right_32(val, sym) \
-({ \
- u32 __ret; \
- asm_inline(".option push\n\t" \
- ".option norvc\n\t" \
- "1:\t" \
- SRLI " %[__ret],%[__val],12\n\t" \
- ".option pop\n\t" \
- ".pushsection runtime_shift_" #sym ",\"a\"\n\t" \
- ".long 1b - .\n\t" \
- ".popsection" \
- : [__ret] "=r" (__ret) \
- : [__val] "r" (val)); \
- __ret; \
-})
+#include <asm/runtime-const-accessors.h>
#define runtime_const_init(type, sym) do { \
extern s32 __start_runtime_##type##_##sym[]; \
diff --git a/arch/x86/include/asm/runtime-const-accessors.h b/arch/x86/include/asm/runtime-const-accessors.h
new file mode 100644
index 000000000000..4c411bc3cb32
--- /dev/null
+++ b/arch/x86/include/asm/runtime-const-accessors.h
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_RUNTIME_CONST_ACCESSORS_H
+#define _ASM_RUNTIME_CONST_ACCESSORS_H
+
+#ifdef MODULE
+#error "this functionality is not available for modules"
+#endif
+
+#ifdef __ASSEMBLY__
+
+.macro RUNTIME_CONST_PTR sym reg
+ movq $0x0123456789abcdef, %\reg
+ 1:
+ .pushsection runtime_ptr_\sym, "a"
+ .long 1b - 8 - .
+ .popsection
+.endm
+
+#else /* __ASSEMBLY__ */
+
+#define runtime_const_ptr(sym) ({ \
+ typeof(sym) __ret; \
+ asm_inline("mov %1,%0\n1:\n" \
+ ".pushsection runtime_ptr_" #sym ",\"a\"\n\t" \
+ ".long 1b - %c2 - .\n" \
+ ".popsection" \
+ :"=r" (__ret) \
+ :"i" ((unsigned long)0x0123456789abcdefull), \
+ "i" (sizeof(long))); \
+ __ret; })
+
+// The 'typeof' will create at _least_ a 32-bit type, but
+// will happily also take a bigger type and the 'shrl' will
+// clear the upper bits
+#define runtime_const_shift_right_32(val, sym) ({ \
+ typeof(0u+(val)) __ret = (val); \
+ asm_inline("shrl $12,%k0\n1:\n" \
+ ".pushsection runtime_shift_" #sym ",\"a\"\n\t" \
+ ".long 1b - 1 - .\n" \
+ ".popsection" \
+ :"+r" (__ret)); \
+ __ret; })
+
+#endif /* __ASSEMBLY__ */
+#endif
diff --git a/arch/x86/include/asm/runtime-const.h b/arch/x86/include/asm/runtime-const.h
index 8d983cfd06ea..15d67e2bfc96 100644
--- a/arch/x86/include/asm/runtime-const.h
+++ b/arch/x86/include/asm/runtime-const.h
@@ -2,41 +2,9 @@
#ifndef _ASM_RUNTIME_CONST_H
#define _ASM_RUNTIME_CONST_H
-#ifdef __ASSEMBLY__
-
-.macro RUNTIME_CONST_PTR sym reg
- movq $0x0123456789abcdef, %\reg
- 1:
- .pushsection runtime_ptr_\sym, "a"
- .long 1b - 8 - .
- .popsection
-.endm
-
-#else /* __ASSEMBLY__ */
-
-#define runtime_const_ptr(sym) ({ \
- typeof(sym) __ret; \
- asm_inline("mov %1,%0\n1:\n" \
- ".pushsection runtime_ptr_" #sym ",\"a\"\n\t" \
- ".long 1b - %c2 - .\n" \
- ".popsection" \
- :"=r" (__ret) \
- :"i" ((unsigned long)0x0123456789abcdefull), \
- "i" (sizeof(long))); \
- __ret; })
-
-// The 'typeof' will create at _least_ a 32-bit type, but
-// will happily also take a bigger type and the 'shrl' will
-// clear the upper bits
-#define runtime_const_shift_right_32(val, sym) ({ \
- typeof(0u+(val)) __ret = (val); \
- asm_inline("shrl $12,%k0\n1:\n" \
- ".pushsection runtime_shift_" #sym ",\"a\"\n\t" \
- ".long 1b - 1 - .\n" \
- ".popsection" \
- :"+r" (__ret)); \
- __ret; })
+#include <asm/runtime-const-accessors.h>
+#ifndef __ASSEMBLY__
#define runtime_const_init(type, sym) do { \
extern s32 __start_runtime_##type##_##sym[]; \
extern s32 __stop_runtime_##type##_##sym[]; \
@@ -70,5 +38,5 @@ static inline void runtime_const_fixup(void (*fn)(void *, unsigned long),
}
}
-#endif /* __ASSEMBLY__ */
+#endif /* !__ASSEMBLY__ */
#endif
--
2.34.1
next prev parent reply other threads:[~2025-10-31 17:42 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-30 10:52 [PATCH v4] fs: hide names_cachep behind runtime access machinery Mateusz Guzik
2025-10-30 13:13 ` kernel test robot
2025-10-30 13:19 ` Mateusz Guzik
2025-10-30 16:15 ` Linus Torvalds
2025-10-30 16:35 ` Mateusz Guzik
2025-10-30 18:07 ` Linus Torvalds
2025-10-30 18:25 ` Linus Torvalds
2025-10-30 21:39 ` Mateusz Guzik
2025-10-30 22:06 ` Mateusz Guzik
2025-10-31 12:08 ` Christian Brauner
2025-10-31 15:13 ` Mateusz Guzik
2025-10-31 16:04 ` Linus Torvalds
2025-10-31 16:25 ` Mateusz Guzik
2025-10-31 16:31 ` Linus Torvalds
2025-10-31 17:42 ` [WIP RFC PATCH 0/3] runtime-const header split and whatnot Mateusz Guzik
2025-10-31 17:42 ` [PATCH 1/3] x86: fix access_ok() and valid_user_address() using wrong USER_PTR_MAX in modules Mateusz Guzik
2025-10-31 21:46 ` Linus Torvalds
2025-10-31 22:01 ` Mateusz Guzik
2025-11-01 11:26 ` David Laight
2025-11-04 6:25 ` Linus Torvalds
2025-11-04 8:56 ` Mateusz Guzik
2025-11-04 9:37 ` Linus Torvalds
2025-11-04 10:25 ` Borislav Petkov
2025-11-04 16:13 ` Borislav Petkov
2025-11-05 1:50 ` Linus Torvalds
2025-11-05 11:37 ` Borislav Petkov
2025-11-05 20:50 ` Mateusz Guzik
2025-11-06 11:14 ` Borislav Petkov
2025-11-06 12:06 ` Mateusz Guzik
2025-11-06 13:10 ` Borislav Petkov
2025-11-06 13:19 ` Mateusz Guzik
2025-11-06 13:36 ` Borislav Petkov
2025-11-06 14:49 ` Mateusz Guzik
2025-11-06 19:26 ` David Laight
2025-11-06 19:49 ` Linus Torvalds
2025-11-04 17:09 ` Sean Christopherson
2025-11-04 19:07 ` Linus Torvalds
2025-11-04 19:34 ` Linus Torvalds
2025-11-04 21:53 ` Sean Christopherson
2025-11-04 20:17 ` Borislav Petkov
2025-11-04 22:06 ` Linus Torvalds
2025-11-05 11:49 ` Borislav Petkov
2025-10-31 17:42 ` Mateusz Guzik [this message]
2025-10-31 17:42 ` [PATCH 3/3] fs: hide names_cachep behind runtime access machinery Mateusz Guzik
2025-10-31 23:30 ` kernel test robot
2025-10-31 23:30 ` kernel test robot
2025-10-31 23:41 ` kernel test robot
2025-11-01 17:49 ` kernel test robot
2025-10-31 13:30 ` [PATCH v4] " kernel test robot
2025-10-31 22:43 ` kernel test robot
2025-11-01 23:06 ` kernel test robot
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