mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-27 21:03:32 +00:00
f328d96d6b
commit68fb3ca0e4upstream. In commit4356e9f841("work around gcc bugs with 'asm goto' with outputs") I did the gcc workaround unconditionally, because the cause of the bad code generation wasn't entirely clear. In the meantime, Jakub Jelinek debugged the issue, and has come up with a fix in gcc [2], which also got backported to the still maintained branches of gcc-11, gcc-12 and gcc-13. Note that while the fix technically wasn't in the original gcc-14 branch, Jakub says: "while it is true that no GCC 14 snapshots until today (or whenever the fix will be committed) have the fix, for GCC trunk it is up to the distros to use the latest snapshot if they use it at all and would allow better testing of the kernel code without the workaround, so that if there are other issues they won't be discovered years later. Most userland code doesn't actually use asm goto with outputs..." so we will consider gcc-14 to be fixed - if somebody is using gcc snapshots of the gcc-14 before the fix, they should upgrade. Note that while the bug goes back to gcc-11, in practice other gcc changes seem to have effectively hidden it since gcc-12.1 as per a bisect by Jakub. So even a gcc-14 snapshot without the fix likely doesn't show actual problems. Also, make the default 'asm_goto_output()' macro mark the asm as volatile by hand, because of an unrelated gcc issue [1] where it doesn't match the documented behavior ("asm goto is always volatile"). Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103979 [1] Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921 [2] Link: https://lore.kernel.org/all/20240208220604.140859-1-seanjc@google.com/ Requested-by: Jakub Jelinek <jakub@redhat.com> Cc: Uros Bizjak <ubizjak@gmail.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Sean Christopherson <seanjc@google.com> Cc: Andrew Pinski <quic_apinski@quicinc.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
169 lines
4.8 KiB
C
169 lines
4.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
|
|
#ifndef __LINUX_COMPILER_TYPES_H
|
|
#error "Please don't include <linux/compiler-gcc.h> directly, include <linux/compiler.h> instead."
|
|
#endif
|
|
|
|
/*
|
|
* Common definitions for all gcc versions go here.
|
|
*/
|
|
#define GCC_VERSION (__GNUC__ * 10000 \
|
|
+ __GNUC_MINOR__ * 100 \
|
|
+ __GNUC_PATCHLEVEL__)
|
|
|
|
/*
|
|
* This macro obfuscates arithmetic on a variable address so that gcc
|
|
* shouldn't recognize the original var, and make assumptions about it.
|
|
*
|
|
* This is needed because the C standard makes it undefined to do
|
|
* pointer arithmetic on "objects" outside their boundaries and the
|
|
* gcc optimizers assume this is the case. In particular they
|
|
* assume such arithmetic does not wrap.
|
|
*
|
|
* A miscompilation has been observed because of this on PPC.
|
|
* To work around it we hide the relationship of the pointer and the object
|
|
* using this macro.
|
|
*
|
|
* Versions of the ppc64 compiler before 4.1 had a bug where use of
|
|
* RELOC_HIDE could trash r30. The bug can be worked around by changing
|
|
* the inline assembly constraint from =g to =r, in this particular
|
|
* case either is valid.
|
|
*/
|
|
#define RELOC_HIDE(ptr, off) \
|
|
({ \
|
|
unsigned long __ptr; \
|
|
__asm__ ("" : "=r"(__ptr) : "0"(ptr)); \
|
|
(typeof(ptr)) (__ptr + (off)); \
|
|
})
|
|
|
|
#ifdef CONFIG_RETPOLINE
|
|
#define __noretpoline __attribute__((__indirect_branch__("keep")))
|
|
#endif
|
|
|
|
#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
|
|
|
|
#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__)
|
|
#define __latent_entropy __attribute__((latent_entropy))
|
|
#endif
|
|
|
|
/*
|
|
* calling noreturn functions, __builtin_unreachable() and __builtin_trap()
|
|
* confuse the stack allocation in gcc, leading to overly large stack
|
|
* frames, see https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82365
|
|
*
|
|
* Adding an empty inline assembly before it works around the problem
|
|
*/
|
|
#define barrier_before_unreachable() asm volatile("")
|
|
|
|
/*
|
|
* Mark a position in code as unreachable. This can be used to
|
|
* suppress control flow warnings after asm blocks that transfer
|
|
* control elsewhere.
|
|
*/
|
|
#define unreachable() \
|
|
do { \
|
|
annotate_unreachable(); \
|
|
barrier_before_unreachable(); \
|
|
__builtin_unreachable(); \
|
|
} while (0)
|
|
|
|
/*
|
|
* GCC 'asm goto' with outputs miscompiles certain code sequences:
|
|
*
|
|
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113921
|
|
*
|
|
* Work around it via the same compiler barrier quirk that we used
|
|
* to use for the old 'asm goto' workaround.
|
|
*
|
|
* Also, always mark such 'asm goto' statements as volatile: all
|
|
* asm goto statements are supposed to be volatile as per the
|
|
* documentation, but some versions of gcc didn't actually do
|
|
* that for asms with outputs:
|
|
*
|
|
* https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98619
|
|
*/
|
|
#ifdef CONFIG_GCC_ASM_GOTO_OUTPUT_WORKAROUND
|
|
#define asm_goto_output(x...) \
|
|
do { asm volatile goto(x); asm (""); } while (0)
|
|
#endif
|
|
|
|
#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP)
|
|
#define __HAVE_BUILTIN_BSWAP32__
|
|
#define __HAVE_BUILTIN_BSWAP64__
|
|
#define __HAVE_BUILTIN_BSWAP16__
|
|
#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
|
|
|
|
#if GCC_VERSION >= 70000
|
|
#define KASAN_ABI_VERSION 5
|
|
#else
|
|
#define KASAN_ABI_VERSION 4
|
|
#endif
|
|
|
|
#ifdef CONFIG_SHADOW_CALL_STACK
|
|
#define __noscs __attribute__((__no_sanitize__("shadow-call-stack")))
|
|
#endif
|
|
|
|
#define __no_sanitize_address __attribute__((__no_sanitize_address__))
|
|
|
|
#if defined(__SANITIZE_THREAD__)
|
|
#define __no_sanitize_thread __attribute__((__no_sanitize_thread__))
|
|
#else
|
|
#define __no_sanitize_thread
|
|
#endif
|
|
|
|
#define __no_sanitize_undefined __attribute__((__no_sanitize_undefined__))
|
|
|
|
/*
|
|
* Only supported since gcc >= 12
|
|
*/
|
|
#if defined(CONFIG_KCOV) && __has_attribute(__no_sanitize_coverage__)
|
|
#define __no_sanitize_coverage __attribute__((__no_sanitize_coverage__))
|
|
#else
|
|
#define __no_sanitize_coverage
|
|
#endif
|
|
|
|
/*
|
|
* Treat __SANITIZE_HWADDRESS__ the same as __SANITIZE_ADDRESS__ in the kernel,
|
|
* matching the defines used by Clang.
|
|
*/
|
|
#ifdef __SANITIZE_HWADDRESS__
|
|
#define __SANITIZE_ADDRESS__
|
|
#endif
|
|
|
|
/*
|
|
* GCC does not support KMSAN.
|
|
*/
|
|
#define __no_sanitize_memory
|
|
#define __no_kmsan_checks
|
|
|
|
/*
|
|
* Turn individual warnings and errors on and off locally, depending
|
|
* on version.
|
|
*/
|
|
#define __diag_GCC(version, severity, s) \
|
|
__diag_GCC_ ## version(__diag_GCC_ ## severity s)
|
|
|
|
/* Severity used in pragma directives */
|
|
#define __diag_GCC_ignore ignored
|
|
#define __diag_GCC_warn warning
|
|
#define __diag_GCC_error error
|
|
|
|
#define __diag_str1(s) #s
|
|
#define __diag_str(s) __diag_str1(s)
|
|
#define __diag(s) _Pragma(__diag_str(GCC diagnostic s))
|
|
|
|
#if GCC_VERSION >= 80000
|
|
#define __diag_GCC_8(s) __diag(s)
|
|
#else
|
|
#define __diag_GCC_8(s)
|
|
#endif
|
|
|
|
#define __diag_ignore_all(option, comment) \
|
|
__diag_GCC(8, ignore, option)
|
|
|
|
/*
|
|
* Prior to 9.1, -Wno-alloc-size-larger-than (and therefore the "alloc_size"
|
|
* attribute) do not work, and must be disabled.
|
|
*/
|
|
#if GCC_VERSION < 90100
|
|
#undef __alloc_size__
|
|
#endif
|