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linux/arch/riscv/include/asm/alternative-macros.h
Nathan Chancellor 61114e734c
riscv: Move alternative length validation into subsection 
After commit 49b290e430 ("riscv: prevent compressed instructions in
alternatives"), builds with LLVM's integrated assembler fail:

  In file included from arch/riscv/mm/init.c:10:
  In file included from ./include/linux/mm.h:29:
  In file included from ./include/linux/pgtable.h:6:
  In file included from ./arch/riscv/include/asm/pgtable.h:108:
  ./arch/riscv/include/asm/tlbflush.h:23:2: error: expected assembly-time absolute expression
          ALT_FLUSH_TLB_PAGE(__asm__ __volatile__ ("sfence.vma %0" : : "r" (addr) : "memory"));
          ^
  ./arch/riscv/include/asm/errata_list.h:33:5: note: expanded from macro 'ALT_FLUSH_TLB_PAGE'
  asm(ALTERNATIVE("sfence.vma %0", "sfence.vma", SIFIVE_VENDOR_ID,        \
      ^
  ./arch/riscv/include/asm/alternative-macros.h:187:2: note: expanded from macro 'ALTERNATIVE'
          _ALTERNATIVE_CFG(old_content, new_content, vendor_id, errata_id, CONFIG_k)
          ^
  ./arch/riscv/include/asm/alternative-macros.h:113:2: note: expanded from macro '_ALTERNATIVE_CFG'
          __ALTERNATIVE_CFG(old_c, new_c, vendor_id, errata_id, IS_ENABLED(CONFIG_k))
          ^
  ./arch/riscv/include/asm/alternative-macros.h:110:2: note: expanded from macro '__ALTERNATIVE_CFG'
          ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c)
          ^
  ./arch/riscv/include/asm/alternative-macros.h:99:3: note: expanded from macro 'ALT_NEW_CONTENT'
          ".org   . - (889b - 888b) + (887b - 886b)\n"                    \
           ^
  <inline asm>:26:6: note: instantiated into assembly here
  .org    . - (889b - 888b) + (887b - 886b)
          ^

This error happens because LLVM's integrated assembler has a one-pass
design, which means it cannot figure out the instruction lengths when
the .org directive is outside of the subsection that contains the
instructions, which was changed by the .option directives added by the
above change.

Move the .org directives before the .previous directive so that these
directives are always within the same subsection, which resolves the
failures and does not introduce any new issues with GNU as. This was
done for arm64 in commit 966a0acce2 ("arm64/alternatives: move length
validation inside the subsection") and commit 22315a2296 ("arm64:
alternatives: Move length validation in alternative_{insn, endif}").

While there is no error from the assembly versions of the macro, they
appear to have the same problem so just make the same change there as
well so that there are no problems in the future.

Link: https://github.com/ClangBuiltLinux/linux/issues/1640
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Link: https://lore.kernel.org/r/20220516214520.3252074-1-nathan@kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
2022-06-02 15:55:22 -07:00

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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __ASM_ALTERNATIVE_MACROS_H
#define __ASM_ALTERNATIVE_MACROS_H
#ifdef CONFIG_RISCV_ALTERNATIVE
#ifdef __ASSEMBLY__
.macro ALT_ENTRY oldptr newptr vendor_id errata_id new_len
RISCV_PTR \oldptr
RISCV_PTR \newptr
REG_ASM \vendor_id
REG_ASM \new_len
.word \errata_id
.endm
.macro ALT_NEW_CONTENT vendor_id, errata_id, enable = 1, new_c : vararg
.if \enable
.pushsection .alternative, "a"
ALT_ENTRY 886b, 888f, \vendor_id, \errata_id, 889f - 888f
.popsection
.subsection 1
888 :
.option push
.option norvc
.option norelax
\new_c
.option pop
889 :
.org . - (889b - 888b) + (887b - 886b)
.org . - (887b - 886b) + (889b - 888b)
.previous
.endif
.endm
.macro __ALTERNATIVE_CFG old_c, new_c, vendor_id, errata_id, enable
886 :
.option push
.option norvc
.option norelax
\old_c
.option pop
887 :
ALT_NEW_CONTENT \vendor_id, \errata_id, \enable, \new_c
.endm
#define _ALTERNATIVE_CFG(old_c, new_c, vendor_id, errata_id, CONFIG_k) \
__ALTERNATIVE_CFG old_c, new_c, vendor_id, errata_id, IS_ENABLED(CONFIG_k)
.macro __ALTERNATIVE_CFG_2 old_c, new_c_1, vendor_id_1, errata_id_1, enable_1, \
new_c_2, vendor_id_2, errata_id_2, enable_2
886 :
.option push
.option norvc
.option norelax
\old_c
.option pop
887 :
ALT_NEW_CONTENT \vendor_id_1, \errata_id_1, \enable_1, \new_c_1
ALT_NEW_CONTENT \vendor_id_2, \errata_id_2, \enable_2, \new_c_2
.endm
#define _ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, errata_id_1, \
CONFIG_k_1, \
new_c_2, vendor_id_2, errata_id_2, \
CONFIG_k_2) \
__ALTERNATIVE_CFG_2 old_c, new_c_1, vendor_id_1, errata_id_1, \
IS_ENABLED(CONFIG_k_1), \
new_c_2, vendor_id_2, errata_id_2, \
IS_ENABLED(CONFIG_k_2)
#else /* !__ASSEMBLY__ */
#include <asm/asm.h>
#include <linux/stringify.h>
#define ALT_ENTRY(oldptr, newptr, vendor_id, errata_id, newlen) \
RISCV_PTR " " oldptr "\n" \
RISCV_PTR " " newptr "\n" \
REG_ASM " " vendor_id "\n" \
REG_ASM " " newlen "\n" \
".word " errata_id "\n"
#define ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c) \
".if " __stringify(enable) " == 1\n" \
".pushsection .alternative, \"a\"\n" \
ALT_ENTRY("886b", "888f", __stringify(vendor_id), __stringify(errata_id), "889f - 888f") \
".popsection\n" \
".subsection 1\n" \
"888 :\n" \
".option push\n" \
".option norvc\n" \
".option norelax\n" \
new_c "\n" \
".option pop\n" \
"889 :\n" \
".org . - (887b - 886b) + (889b - 888b)\n" \
".org . - (889b - 888b) + (887b - 886b)\n" \
".previous\n" \
".endif\n"
#define __ALTERNATIVE_CFG(old_c, new_c, vendor_id, errata_id, enable) \
"886 :\n" \
".option push\n" \
".option norvc\n" \
".option norelax\n" \
old_c "\n" \
".option pop\n" \
"887 :\n" \
ALT_NEW_CONTENT(vendor_id, errata_id, enable, new_c)
#define _ALTERNATIVE_CFG(old_c, new_c, vendor_id, errata_id, CONFIG_k) \
__ALTERNATIVE_CFG(old_c, new_c, vendor_id, errata_id, IS_ENABLED(CONFIG_k))
#define __ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, errata_id_1, \
enable_1, \
new_c_2, vendor_id_2, errata_id_2, \
enable_2) \
"886 :\n" \
".option push\n" \
".option norvc\n" \
".option norelax\n" \
old_c "\n" \
".option pop\n" \
"887 :\n" \
ALT_NEW_CONTENT(vendor_id_1, errata_id_1, enable_1, new_c_1) \
ALT_NEW_CONTENT(vendor_id_2, errata_id_2, enable_2, new_c_2)
#define _ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, errata_id_1, \
CONFIG_k_1, \
new_c_2, vendor_id_2, errata_id_2, \
CONFIG_k_2) \
__ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, errata_id_1, \
IS_ENABLED(CONFIG_k_1), \
new_c_2, vendor_id_2, errata_id_2, \
IS_ENABLED(CONFIG_k_2))
#endif /* __ASSEMBLY__ */
#else /* CONFIG_RISCV_ALTERNATIVE */
#ifdef __ASSEMBLY__
.macro __ALTERNATIVE_CFG old_c
\old_c
.endm
#define _ALTERNATIVE_CFG(old_c, new_c, vendor_id, errata_id, CONFIG_k) \
__ALTERNATIVE_CFG old_c
#define _ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, errata_id_1, \
CONFIG_k_1, \
new_c_2, vendor_id_2, errata_id_2, \
CONFIG_k_2) \
__ALTERNATIVE_CFG old_c
#else /* !__ASSEMBLY__ */
#define __ALTERNATIVE_CFG(old_c) \
old_c "\n"
#define _ALTERNATIVE_CFG(old_c, new_c, vendor_id, errata_id, CONFIG_k) \
__ALTERNATIVE_CFG(old_c)
#define _ALTERNATIVE_CFG_2(old_c, new_c_1, vendor_id_1, errata_id_1, \
CONFIG_k_1, \
new_c_2, vendor_id_2, errata_id_2, \
CONFIG_k_2) \
__ALTERNATIVE_CFG(old_c)
#endif /* __ASSEMBLY__ */
#endif /* CONFIG_RISCV_ALTERNATIVE */
/*
* Usage:
* ALTERNATIVE(old_content, new_content, vendor_id, errata_id, CONFIG_k)
* in the assembly code. Otherwise,
* asm(ALTERNATIVE(old_content, new_content, vendor_id, errata_id, CONFIG_k));
*
* old_content: The old content which is probably replaced with new content.
* new_content: The new content.
* vendor_id: The CPU vendor ID.
* errata_id: The errata ID.
* CONFIG_k: The Kconfig of this errata. When Kconfig is disabled, the old
* content will alwyas be executed.
*/
#define ALTERNATIVE(old_content, new_content, vendor_id, errata_id, CONFIG_k) \
_ALTERNATIVE_CFG(old_content, new_content, vendor_id, errata_id, CONFIG_k)
/*
* A vendor wants to replace an old_content, but another vendor has used
* ALTERNATIVE() to patch its customized content at the same location. In
* this case, this vendor can create a new macro ALTERNATIVE_2() based
* on the following sample code and then replace ALTERNATIVE() with
* ALTERNATIVE_2() to append its customized content.
*/
#define ALTERNATIVE_2(old_content, new_content_1, vendor_id_1, \
errata_id_1, CONFIG_k_1, \
new_content_2, vendor_id_2, \
errata_id_2, CONFIG_k_2) \
_ALTERNATIVE_CFG_2(old_content, new_content_1, vendor_id_1, \
errata_id_1, CONFIG_k_1, \
new_content_2, vendor_id_2, \
errata_id_2, CONFIG_k_2)
#endif
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