* [PATCH v2 01/14] s390/boot: perfer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
@ 2019-08-27 20:39 ` Nick Desaulniers
2019-08-27 20:39 ` [PATCH v2 02/14] include/linux/compiler.h: prefer " Nick Desaulniers
` (14 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:39 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/s390/boot/startup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index 7b0d05414618..26493c4ff04b 100644
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -46,7 +46,7 @@ struct diag_ops __bootdata_preserved(diag_dma_ops) = {
.diag0c = _diag0c_dma,
.diag308_reset = _diag308_reset_dma
};
-static struct diag210 _diag210_tmp_dma __section(".dma.data");
+static struct diag210 _diag210_tmp_dma __section(.dma.data);
struct diag210 *__bootdata_preserved(__diag210_tmp_dma) = &_diag210_tmp_dma;
void _swsusp_reset_dma(void);
unsigned long __bootdata_preserved(__swsusp_reset_dma) = __pa(_swsusp_reset_dma);
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 02/14] include/linux/compiler.h: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
2019-08-27 20:39 ` [PATCH v2 01/14] s390/boot: perfer " Nick Desaulniers
@ 2019-08-27 20:39 ` Nick Desaulniers
2019-08-27 20:39 ` [PATCH v2 03/14] parisc: " Nick Desaulniers
` (13 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:39 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers, stable
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
This fixes an Oops observed in distro's that use systemd and not
net.core.bpf_jit_enable=1, when their kernels are compiled with Clang.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Link: Link: https://github.com/ClangBuiltLinux/linux/issues/619
Cc: <stable@vger.kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
include/linux/compiler.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index f0fd5636fddb..5e88e7e33abe 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -24,7 +24,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
long ______r; \
static struct ftrace_likely_data \
__aligned(4) \
- __section("_ftrace_annotated_branch") \
+ __section(_ftrace_annotated_branch) \
______f = { \
.data.func = __func__, \
.data.file = __FILE__, \
@@ -60,7 +60,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
#define __trace_if_value(cond) ({ \
static struct ftrace_branch_data \
__aligned(4) \
- __section("_ftrace_branch") \
+ __section(_ftrace_branch) \
__if_trace = { \
.func = __func__, \
.file = __FILE__, \
@@ -118,7 +118,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
".popsection\n\t"
/* Annotate a C jump table to allow objtool to follow the code flow */
-#define __annotate_jump_table __section(".rodata..c_jump_table")
+#define __annotate_jump_table __section(.rodata..c_jump_table)
#else
#define annotate_reachable()
@@ -298,7 +298,7 @@ unsigned long read_word_at_a_time(const void *addr)
* visible to the compiler.
*/
#define __ADDRESSABLE(sym) \
- static void * __section(".discard.addressable") __used \
+ static void * __section(.discard.addressable) __used \
__PASTE(__addressable_##sym, __LINE__) = (void *)&sym;
/**
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 03/14] parisc: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
2019-08-27 20:39 ` [PATCH v2 01/14] s390/boot: perfer " Nick Desaulniers
2019-08-27 20:39 ` [PATCH v2 02/14] include/linux/compiler.h: prefer " Nick Desaulniers
@ 2019-08-27 20:39 ` Nick Desaulniers
2019-08-27 20:39 ` [PATCH v2 04/14] um: " Nick Desaulniers
` (12 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:39 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/parisc/include/asm/cache.h | 2 +-
arch/parisc/include/asm/ldcw.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/parisc/include/asm/cache.h b/arch/parisc/include/asm/cache.h
index 73ca89a47f49..e5de3f897633 100644
--- a/arch/parisc/include/asm/cache.h
+++ b/arch/parisc/include/asm/cache.h
@@ -22,7 +22,7 @@
#define ARCH_DMA_MINALIGN L1_CACHE_BYTES
-#define __read_mostly __attribute__((__section__(".data..read_mostly")))
+#define __read_mostly __section(.data..read_mostly)
void parisc_cache_init(void); /* initializes cache-flushing */
void disable_sr_hashing_asm(int); /* low level support for above */
diff --git a/arch/parisc/include/asm/ldcw.h b/arch/parisc/include/asm/ldcw.h
index 3eb4bfc1fb36..e080143e79a3 100644
--- a/arch/parisc/include/asm/ldcw.h
+++ b/arch/parisc/include/asm/ldcw.h
@@ -52,7 +52,7 @@
})
#ifdef CONFIG_SMP
-# define __lock_aligned __attribute__((__section__(".data..lock_aligned")))
+# define __lock_aligned __section(.data..lock_aligned)
#endif
#endif /* __PARISC_LDCW_H */
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 04/14] um: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (2 preceding siblings ...)
2019-08-27 20:39 ` [PATCH v2 03/14] parisc: " Nick Desaulniers
@ 2019-08-27 20:39 ` Nick Desaulniers
2019-08-27 20:39 ` [PATCH v2 05/14] ia64: " Nick Desaulniers
` (11 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:39 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/um/kernel/um_arch.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index a818ccef30ca..18e0287dd97e 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -52,9 +52,9 @@ struct cpuinfo_um boot_cpu_data = {
.ipi_pipe = { -1, -1 }
};
-union thread_union cpu0_irqstack
- __attribute__((__section__(".data..init_irqstack"))) =
- { .thread_info = INIT_THREAD_INFO(init_task) };
+union thread_union cpu0_irqstack __section(.data..init_irqstack) = {
+ .thread_info = INIT_THREAD_INFO(init_task)
+};
/* Changed in setup_arch, which is called in early boot */
static char host_info[(__NEW_UTS_LEN + 1) * 5];
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 05/14] ia64: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (3 preceding siblings ...)
2019-08-27 20:39 ` [PATCH v2 04/14] um: " Nick Desaulniers
@ 2019-08-27 20:39 ` Nick Desaulniers
2019-08-27 20:39 ` [PATCH v2 06/14] arm: " Nick Desaulniers
` (10 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:39 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/ia64/include/asm/cache.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/ia64/include/asm/cache.h b/arch/ia64/include/asm/cache.h
index 4eb6f742d14f..7decf91ca11a 100644
--- a/arch/ia64/include/asm/cache.h
+++ b/arch/ia64/include/asm/cache.h
@@ -25,6 +25,6 @@
# define SMP_CACHE_BYTES (1 << 3)
#endif
-#define __read_mostly __attribute__((__section__(".data..read_mostly")))
+#define __read_mostly __section(.data..read_mostly)
#endif /* _ASM_IA64_CACHE_H */
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 06/14] arm: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (4 preceding siblings ...)
2019-08-27 20:39 ` [PATCH v2 05/14] ia64: " Nick Desaulniers
@ 2019-08-27 20:39 ` Nick Desaulniers
2019-08-27 20:40 ` [PATCH v2 07/14] mips: " Nick Desaulniers
` (9 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:39 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/arm/include/asm/cache.h | 2 +-
arch/arm/include/asm/mach/arch.h | 4 ++--
arch/arm/include/asm/setup.h | 2 +-
3 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/arm/include/asm/cache.h b/arch/arm/include/asm/cache.h
index 1d65ed3a2755..cc06079600e0 100644
--- a/arch/arm/include/asm/cache.h
+++ b/arch/arm/include/asm/cache.h
@@ -24,6 +24,6 @@
#define ARCH_SLAB_MINALIGN 8
#endif
-#define __read_mostly __attribute__((__section__(".data..read_mostly")))
+#define __read_mostly __section(.data..read_mostly)
#endif
diff --git a/arch/arm/include/asm/mach/arch.h b/arch/arm/include/asm/mach/arch.h
index e7df5a822cab..2986f6b4862d 100644
--- a/arch/arm/include/asm/mach/arch.h
+++ b/arch/arm/include/asm/mach/arch.h
@@ -81,7 +81,7 @@ extern const struct machine_desc __arch_info_begin[], __arch_info_end[];
#define MACHINE_START(_type,_name) \
static const struct machine_desc __mach_desc_##_type \
__used \
- __attribute__((__section__(".arch.info.init"))) = { \
+ __section(.arch.info.init) = { \
.nr = MACH_TYPE_##_type, \
.name = _name,
@@ -91,7 +91,7 @@ static const struct machine_desc __mach_desc_##_type \
#define DT_MACHINE_START(_name, _namestr) \
static const struct machine_desc __mach_desc_##_name \
__used \
- __attribute__((__section__(".arch.info.init"))) = { \
+ __section(.arch.info.init) = { \
.nr = ~0, \
.name = _namestr,
diff --git a/arch/arm/include/asm/setup.h b/arch/arm/include/asm/setup.h
index 67d20712cb48..00190f1f0574 100644
--- a/arch/arm/include/asm/setup.h
+++ b/arch/arm/include/asm/setup.h
@@ -14,7 +14,7 @@
#include <uapi/asm/setup.h>
-#define __tag __used __attribute__((__section__(".taglist.init")))
+#define __tag __used __section(.taglist.init)
#define __tagtable(tag, fn) \
static const struct tagtable __tagtable_##fn __tag = { tag, fn }
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 07/14] mips: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (5 preceding siblings ...)
2019-08-27 20:39 ` [PATCH v2 06/14] arm: " Nick Desaulniers
@ 2019-08-27 20:40 ` Nick Desaulniers
2019-08-27 20:40 ` [PATCH v2 08/14] sparc: " Nick Desaulniers
` (8 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:40 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Acked-by: Paul Burton <paul.burton@mips.com>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/mips/include/asm/cache.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/include/asm/cache.h b/arch/mips/include/asm/cache.h
index 8b14c2706aa5..af2d943580ee 100644
--- a/arch/mips/include/asm/cache.h
+++ b/arch/mips/include/asm/cache.h
@@ -14,6 +14,6 @@
#define L1_CACHE_SHIFT CONFIG_MIPS_L1_CACHE_SHIFT
#define L1_CACHE_BYTES (1 << L1_CACHE_SHIFT)
-#define __read_mostly __attribute__((__section__(".data..read_mostly")))
+#define __read_mostly __section(.data..read_mostly)
#endif /* _ASM_CACHE_H */
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 08/14] sparc: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (6 preceding siblings ...)
2019-08-27 20:40 ` [PATCH v2 07/14] mips: " Nick Desaulniers
@ 2019-08-27 20:40 ` Nick Desaulniers
2019-08-27 20:40 ` [PATCH v2 09/14] powerpc: prefer __section and __printf " Nick Desaulniers
` (7 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:40 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Acked-by: David S. Miller <davem@davemloft.net>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/sparc/include/asm/cache.h | 2 +-
arch/sparc/kernel/btext.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/sparc/include/asm/cache.h b/arch/sparc/include/asm/cache.h
index dcfd58118c11..9a9effdd01e2 100644
--- a/arch/sparc/include/asm/cache.h
+++ b/arch/sparc/include/asm/cache.h
@@ -21,6 +21,6 @@
#define SMP_CACHE_BYTES (1 << SMP_CACHE_BYTES_SHIFT)
-#define __read_mostly __attribute__((__section__(".data..read_mostly")))
+#define __read_mostly __section(.data..read_mostly)
#endif /* !(_SPARC_CACHE_H) */
diff --git a/arch/sparc/kernel/btext.c b/arch/sparc/kernel/btext.c
index 5869773f3dc4..b2eff8f8f27b 100644
--- a/arch/sparc/kernel/btext.c
+++ b/arch/sparc/kernel/btext.c
@@ -24,7 +24,7 @@ static void draw_byte_32(unsigned char *bits, unsigned int *base, int rb);
static void draw_byte_16(unsigned char *bits, unsigned int *base, int rb);
static void draw_byte_8(unsigned char *bits, unsigned int *base, int rb);
-#define __force_data __attribute__((__section__(".data")))
+#define __force_data __section(.data)
static int g_loc_X __force_data;
static int g_loc_Y __force_data;
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 09/14] powerpc: prefer __section and __printf from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (7 preceding siblings ...)
2019-08-27 20:40 ` [PATCH v2 08/14] sparc: " Nick Desaulniers
@ 2019-08-27 20:40 ` Nick Desaulniers
2019-08-27 20:40 ` [PATCH v2 10/14] x86: prefer __section " Nick Desaulniers
` (6 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:40 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/powerpc/boot/main.c | 3 +--
arch/powerpc/boot/ps3.c | 6 ++----
arch/powerpc/include/asm/cache.h | 2 +-
arch/powerpc/kernel/btext.c | 2 +-
4 files changed, 5 insertions(+), 8 deletions(-)
diff --git a/arch/powerpc/boot/main.c b/arch/powerpc/boot/main.c
index 102cc546444d..3ccc84e06fc4 100644
--- a/arch/powerpc/boot/main.c
+++ b/arch/powerpc/boot/main.c
@@ -150,8 +150,7 @@ static struct addr_range prep_initrd(struct addr_range vmlinux, void *chosen,
* edit the command line passed to vmlinux (by setting /chosen/bootargs).
* The buffer is put in it's own section so that tools may locate it easier.
*/
-static char cmdline[BOOT_COMMAND_LINE_SIZE]
- __attribute__((__section__("__builtin_cmdline")));
+static char cmdline[BOOT_COMMAND_LINE_SIZE] __section(__builtin_cmdline);
static void prep_cmdline(void *chosen)
{
diff --git a/arch/powerpc/boot/ps3.c b/arch/powerpc/boot/ps3.c
index c52552a681c5..70b2ed82d2de 100644
--- a/arch/powerpc/boot/ps3.c
+++ b/arch/powerpc/boot/ps3.c
@@ -24,8 +24,7 @@ extern int lv1_get_repository_node_value(u64 in_1, u64 in_2, u64 in_3,
#ifdef DEBUG
#define DBG(fmt...) printf(fmt)
#else
-static inline int __attribute__ ((format (printf, 1, 2))) DBG(
- const char *fmt, ...) {return 0;}
+static inline int __printf(1, 2) DBG(const char *fmt, ...) { return 0; }
#endif
BSS_STACK(4096);
@@ -35,8 +34,7 @@ BSS_STACK(4096);
* The buffer is put in it's own section so that tools may locate it easier.
*/
-static char cmdline[BOOT_COMMAND_LINE_SIZE]
- __attribute__((__section__("__builtin_cmdline")));
+static char cmdline[BOOT_COMMAND_LINE_SIZE] __section(__builtin_cmdline);
static void prep_cmdline(void *chosen)
{
diff --git a/arch/powerpc/include/asm/cache.h b/arch/powerpc/include/asm/cache.h
index 45e3137ccd71..9114495855eb 100644
--- a/arch/powerpc/include/asm/cache.h
+++ b/arch/powerpc/include/asm/cache.h
@@ -91,7 +91,7 @@ static inline u32 l1_cache_bytes(void)
isync
#else
-#define __read_mostly __attribute__((__section__(".data..read_mostly")))
+#define __read_mostly __section(.data..read_mostly)
#ifdef CONFIG_PPC_BOOK3S_32
extern long _get_L2CR(void);
diff --git a/arch/powerpc/kernel/btext.c b/arch/powerpc/kernel/btext.c
index 6dfceaa820e4..f57712a55815 100644
--- a/arch/powerpc/kernel/btext.c
+++ b/arch/powerpc/kernel/btext.c
@@ -26,7 +26,7 @@
static void scrollscreen(void);
#endif
-#define __force_data __attribute__((__section__(".data")))
+#define __force_data __section(.data)
static int g_loc_X __force_data;
static int g_loc_Y __force_data;
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 10/14] x86: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (8 preceding siblings ...)
2019-08-27 20:40 ` [PATCH v2 09/14] powerpc: prefer __section and __printf " Nick Desaulniers
@ 2019-08-27 20:40 ` Nick Desaulniers
2019-08-27 20:40 ` [PATCH v2 11/14] include/asm-generic: " Nick Desaulniers
` (5 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:40 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
arch/x86/include/asm/cache.h | 2 +-
arch/x86/include/asm/intel-mid.h | 2 +-
arch/x86/include/asm/iommu_table.h | 5 ++---
arch/x86/include/asm/irqflags.h | 2 +-
arch/x86/include/asm/mem_encrypt.h | 2 +-
arch/x86/kernel/cpu/cpu.h | 3 +--
6 files changed, 7 insertions(+), 9 deletions(-)
diff --git a/arch/x86/include/asm/cache.h b/arch/x86/include/asm/cache.h
index abe08690a887..bb9f4bf4ec02 100644
--- a/arch/x86/include/asm/cache.h
+++ b/arch/x86/include/asm/cache.h
@@ -8,7 +8,7 @@
#define L1_CACHE_SHIFT (CONFIG_X86_L1_CACHE_SHIFT)
#define L1_CACHE_BYTES (1 << L1_CACHE_SHIFT)
-#define __read_mostly __attribute__((__section__(".data..read_mostly")))
+#define __read_mostly __section(.data..read_mostly)
#define INTERNODE_CACHE_SHIFT CONFIG_X86_INTERNODE_CACHE_SHIFT
#define INTERNODE_CACHE_BYTES (1 << INTERNODE_CACHE_SHIFT)
diff --git a/arch/x86/include/asm/intel-mid.h b/arch/x86/include/asm/intel-mid.h
index 8e5af119dc2d..f51f04aefe1b 100644
--- a/arch/x86/include/asm/intel-mid.h
+++ b/arch/x86/include/asm/intel-mid.h
@@ -43,7 +43,7 @@ struct devs_id {
#define sfi_device(i) \
static const struct devs_id *const __intel_mid_sfi_##i##_dev __used \
- __attribute__((__section__(".x86_intel_mid_dev.init"))) = &i
+ __section(.x86_intel_mid_dev.init) = &i
/**
* struct mid_sd_board_info - template for SD device creation
diff --git a/arch/x86/include/asm/iommu_table.h b/arch/x86/include/asm/iommu_table.h
index 1fb3fd1a83c2..7d190710eb92 100644
--- a/arch/x86/include/asm/iommu_table.h
+++ b/arch/x86/include/asm/iommu_table.h
@@ -50,9 +50,8 @@ struct iommu_table_entry {
#define __IOMMU_INIT(_detect, _depend, _early_init, _late_init, _finish)\
static const struct iommu_table_entry \
- __iommu_entry_##_detect __used \
- __attribute__ ((unused, __section__(".iommu_table"), \
- aligned((sizeof(void *))))) \
+ __iommu_entry_##_detect __used __section(.iommu_table) \
+ __aligned((sizeof(void *))) \
= {_detect, _depend, _early_init, _late_init, \
_finish ? IOMMU_FINISH_IF_DETECTED : 0}
/*
diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index 8a0e56e1dcc9..68db90bca813 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -9,7 +9,7 @@
#include <asm/nospec-branch.h>
/* Provide __cpuidle; we can't safely include <linux/cpu.h> */
-#define __cpuidle __attribute__((__section__(".cpuidle.text")))
+#define __cpuidle __section(.cpuidle.text)
/*
* Interrupt control:
diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h
index 0c196c47d621..db2cd3709148 100644
--- a/arch/x86/include/asm/mem_encrypt.h
+++ b/arch/x86/include/asm/mem_encrypt.h
@@ -50,7 +50,7 @@ void __init mem_encrypt_free_decrypted_mem(void);
bool sme_active(void);
bool sev_active(void);
-#define __bss_decrypted __attribute__((__section__(".bss..decrypted")))
+#define __bss_decrypted __section(.bss..decrypted)
#else /* !CONFIG_AMD_MEM_ENCRYPT */
diff --git a/arch/x86/kernel/cpu/cpu.h b/arch/x86/kernel/cpu/cpu.h
index c0e2407abdd6..7ff9dc41a603 100644
--- a/arch/x86/kernel/cpu/cpu.h
+++ b/arch/x86/kernel/cpu/cpu.h
@@ -38,8 +38,7 @@ struct _tlb_table {
#define cpu_dev_register(cpu_devX) \
static const struct cpu_dev *const __cpu_dev_##cpu_devX __used \
- __attribute__((__section__(".x86_cpu_dev.init"))) = \
- &cpu_devX;
+ __section(.x86_cpu_dev.init) = &cpu_devX;
extern const struct cpu_dev *const __x86_cpu_dev_start[],
*const __x86_cpu_dev_end[];
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 11/14] include/asm-generic: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (9 preceding siblings ...)
2019-08-27 20:40 ` [PATCH v2 10/14] x86: prefer __section " Nick Desaulniers
@ 2019-08-27 20:40 ` Nick Desaulniers
2019-08-27 20:40 ` [PATCH v2 12/14] include/linux: " Nick Desaulniers
` (4 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:40 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
include/asm-generic/error-injection.h | 2 +-
include/asm-generic/kprobes.h | 5 ++---
2 files changed, 3 insertions(+), 4 deletions(-)
diff --git a/include/asm-generic/error-injection.h b/include/asm-generic/error-injection.h
index 95a159a4137f..a593a50b33e3 100644
--- a/include/asm-generic/error-injection.h
+++ b/include/asm-generic/error-injection.h
@@ -23,7 +23,7 @@ struct error_injection_entry {
*/
#define ALLOW_ERROR_INJECTION(fname, _etype) \
static struct error_injection_entry __used \
- __attribute__((__section__("_error_injection_whitelist"))) \
+ __section(_error_injection_whitelist) \
_eil_addr_##fname = { \
.addr = (unsigned long)fname, \
.etype = EI_ETYPE_##_etype, \
diff --git a/include/asm-generic/kprobes.h b/include/asm-generic/kprobes.h
index 4a982089c95c..20d69719270f 100644
--- a/include/asm-generic/kprobes.h
+++ b/include/asm-generic/kprobes.h
@@ -9,12 +9,11 @@
* by using this macro.
*/
# define __NOKPROBE_SYMBOL(fname) \
-static unsigned long __used \
- __attribute__((__section__("_kprobe_blacklist"))) \
+static unsigned long __used __section(_kprobe_blacklist) \
_kbl_addr_##fname = (unsigned long)fname;
# define NOKPROBE_SYMBOL(fname) __NOKPROBE_SYMBOL(fname)
/* Use this to forbid a kprobes attach on very low level functions */
-# define __kprobes __attribute__((__section__(".kprobes.text")))
+# define __kprobes __section(.kprobes.text)
# define nokprobe_inline __always_inline
#else
# define NOKPROBE_SYMBOL(fname)
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 12/14] include/linux: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (10 preceding siblings ...)
2019-08-27 20:40 ` [PATCH v2 11/14] include/asm-generic: " Nick Desaulniers
@ 2019-08-27 20:40 ` Nick Desaulniers
2019-08-27 20:40 ` [PATCH v2 13/14] include/linux/compiler.h: remove unused KENTRY macro Nick Desaulniers
` (3 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:40 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Acked-by: Will Deacon <will@kernel.org>
Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
Suggested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
include/linux/cache.h | 6 +++---
include/linux/cpu.h | 2 +-
include/linux/export.h | 2 +-
include/linux/init_task.h | 4 ++--
include/linux/interrupt.h | 5 ++---
include/linux/sched/debug.h | 2 +-
include/linux/srcutree.h | 2 +-
7 files changed, 11 insertions(+), 12 deletions(-)
diff --git a/include/linux/cache.h b/include/linux/cache.h
index 750621e41d1c..3f4df9eef1e1 100644
--- a/include/linux/cache.h
+++ b/include/linux/cache.h
@@ -28,7 +28,7 @@
* but may get written to during init, so can't live in .rodata (via "const").
*/
#ifndef __ro_after_init
-#define __ro_after_init __attribute__((__section__(".data..ro_after_init")))
+#define __ro_after_init __section(.data..ro_after_init)
#endif
#ifndef ____cacheline_aligned
@@ -45,8 +45,8 @@
#ifndef __cacheline_aligned
#define __cacheline_aligned \
- __attribute__((__aligned__(SMP_CACHE_BYTES), \
- __section__(".data..cacheline_aligned")))
+ __aligned(SMP_CACHE_BYTES) \
+ __section(.data..cacheline_aligned)
#endif /* __cacheline_aligned */
#ifndef __cacheline_aligned_in_smp
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index fcb1386bb0d4..186bbd79d6ce 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -166,7 +166,7 @@ void cpu_startup_entry(enum cpuhp_state state);
void cpu_idle_poll_ctrl(bool enable);
/* Attach to any functions which should be considered cpuidle. */
-#define __cpuidle __attribute__((__section__(".cpuidle.text")))
+#define __cpuidle __section(.cpuidle.text)
bool cpu_in_idle(unsigned long pc);
diff --git a/include/linux/export.h b/include/linux/export.h
index fd8711ed9ac4..808c1a0c2ef9 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -104,7 +104,7 @@ struct kernel_symbol {
* discarded in the final link stage.
*/
#define __ksym_marker(sym) \
- static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
+ static int __ksym_marker_##sym[0] __section(.discard.ksym) __used
#define __EXPORT_SYMBOL(sym, sec) \
__ksym_marker(sym); \
diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 6049baa5b8bc..50139505da34 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -51,12 +51,12 @@ extern struct cred init_cred;
/* Attach to the init_task data structure for proper alignment */
#ifdef CONFIG_ARCH_TASK_STRUCT_ON_STACK
-#define __init_task_data __attribute__((__section__(".data..init_task")))
+#define __init_task_data __section(.data..init_task)
#else
#define __init_task_data /**/
#endif
/* Attach to the thread_info data structure for proper alignment */
-#define __init_thread_info __attribute__((__section__(".data..init_thread_info")))
+#define __init_thread_info __section(.data..init_thread_info)
#endif
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 5b8328a99b2a..29debfe4dd0f 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -741,8 +741,7 @@ extern int arch_early_irq_init(void);
/*
* We want to know which function is an entrypoint of a hardirq or a softirq.
*/
-#define __irq_entry __attribute__((__section__(".irqentry.text")))
-#define __softirq_entry \
- __attribute__((__section__(".softirqentry.text")))
+#define __irq_entry __section(.irqentry.text)
+#define __softirq_entry __section(.softirqentry.text)
#endif
diff --git a/include/linux/sched/debug.h b/include/linux/sched/debug.h
index 95fb9e025247..e17b66221fdd 100644
--- a/include/linux/sched/debug.h
+++ b/include/linux/sched/debug.h
@@ -42,7 +42,7 @@ extern void proc_sched_set_task(struct task_struct *p);
#endif
/* Attach to any functions which should be ignored in wchan output. */
-#define __sched __attribute__((__section__(".sched.text")))
+#define __sched __section(.sched.text)
/* Linker adds these: start and end of __sched functions */
extern char __sched_text_start[], __sched_text_end[];
diff --git a/include/linux/srcutree.h b/include/linux/srcutree.h
index 9cfcc8a756ae..9de652f4e1bd 100644
--- a/include/linux/srcutree.h
+++ b/include/linux/srcutree.h
@@ -124,7 +124,7 @@ struct srcu_struct {
# define __DEFINE_SRCU(name, is_static) \
is_static struct srcu_struct name; \
struct srcu_struct * const __srcu_struct_##name \
- __section("___srcu_struct_ptrs") = &name
+ __section(___srcu_struct_ptrs) = &name
#else
# define __DEFINE_SRCU(name, is_static) \
static DEFINE_PER_CPU(struct srcu_data, name##_srcu_data); \
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 13/14] include/linux/compiler.h: remove unused KENTRY macro
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (11 preceding siblings ...)
2019-08-27 20:40 ` [PATCH v2 12/14] include/linux: " Nick Desaulniers
@ 2019-08-27 20:40 ` Nick Desaulniers
2019-08-27 20:40 ` [PATCH v2 14/14] compiler_attributes.h: add note about __section Nick Desaulniers
` (2 subsequent siblings)
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:40 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
This macro is not used throughout the kernel. Delete it rather than
update the __section to be a fully spelled out
__attribute__((__section__())) to avoid
https://bugs.llvm.org/show_bug.cgi?id=42950.
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
include/linux/compiler.h | 23 -----------------------
1 file changed, 23 deletions(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 5e88e7e33abe..f01c1e527f85 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -136,29 +136,6 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
} while (0)
#endif
-/*
- * KENTRY - kernel entry point
- * This can be used to annotate symbols (functions or data) that are used
- * without their linker symbol being referenced explicitly. For example,
- * interrupt vector handlers, or functions in the kernel image that are found
- * programatically.
- *
- * Not required for symbols exported with EXPORT_SYMBOL, or initcalls. Those
- * are handled in their own way (with KEEP() in linker scripts).
- *
- * KENTRY can be avoided if the symbols in question are marked as KEEP() in the
- * linker script. For example an architecture could KEEP() its entire
- * boot/exception vector code rather than annotate each function and data.
- */
-#ifndef KENTRY
-# define KENTRY(sym) \
- extern typeof(sym) sym; \
- static const unsigned long __kentry_##sym \
- __used \
- __section("___kentry" "+" #sym ) \
- = (unsigned long)&sym;
-#endif
-
#ifndef RELOC_HIDE
# define RELOC_HIDE(ptr, off) \
({ unsigned long __ptr; \
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* [PATCH v2 14/14] compiler_attributes.h: add note about __section
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (12 preceding siblings ...)
2019-08-27 20:40 ` [PATCH v2 13/14] include/linux/compiler.h: remove unused KENTRY macro Nick Desaulniers
@ 2019-08-27 20:40 ` Nick Desaulniers
2019-08-28 2:47 ` [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Joe Perches
2019-08-28 9:59 ` Sedat Dilek
15 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-27 20:40 UTC (permalink / raw)
To: miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel, Nick Desaulniers
GCC unescapes escaped string section names while Clang does not. Because
__section uses the `#` stringification operator for the section name, it
doesn't need to be escaped.
Instead, we should:
1. Prefer __section(.section_name_no_quotes).
2. Only use __attribute__((__section(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
This antipattern was found with:
$ grep -e __section\(\" -e __section__\(\" -r
See the discussions in:
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://marc.info/?l=linux-netdev&m=156412960619946&w=2
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
include/linux/compiler_attributes.h | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
index 6b318efd8a74..f8c008d7f616 100644
--- a/include/linux/compiler_attributes.h
+++ b/include/linux/compiler_attributes.h
@@ -225,6 +225,16 @@
#define __pure __attribute__((__pure__))
/*
+ * Note: Since this macro makes use of the "stringification operator" `#`, a
+ * quoted string literal should not be passed to it. eg.
+ * prefer:
+ * __section(.foo)
+ * to:
+ * __section(".foo")
+ * unless the section name is dynamically built up, in which case the
+ * verbose __attribute__((__section__(".foo" x))) should be preferred.
+ * See also: https://bugs.llvm.org/show_bug.cgi?id=42950
+ *
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute
* gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute
* clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate
--
2.23.0.187.g17f5b7556c-goog
^ permalink raw reply related [flat|nested] 20+ messages in thread* Re: [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (13 preceding siblings ...)
2019-08-27 20:40 ` [PATCH v2 14/14] compiler_attributes.h: add note about __section Nick Desaulniers
@ 2019-08-28 2:47 ` Joe Perches
2019-08-28 22:44 ` Nick Desaulniers
2019-08-28 9:59 ` Sedat Dilek
15 siblings, 1 reply; 20+ messages in thread
From: Joe Perches @ 2019-08-28 2:47 UTC (permalink / raw)
To: Nick Desaulniers, miguel.ojeda.sandonis
Cc: sedat.dilek, will, jpoimboe, naveen.n.rao, davem, paul.burton,
clang-built-linux, linux-kernel
On Tue, 2019-08-27 at 13:39 -0700, Nick Desaulniers wrote:
> GCC unescapes escaped string section names while Clang does not. Because
> __section uses the `#` stringification operator for the section name, it
> doesn't need to be escaped.
>
> This fixes an Oops observed in distro's that use systemd and not
> net.core.bpf_jit_enable=1, when their kernels are compiled with Clang.
>
> Instead, we should:
> 1. Prefer __section(.section_name_no_quotes).
> 2. Only use __attribute__((__section(".section"))) when creating the
Please use __ before and after section
i.e. __attribute__((__section__("<section_name>")))
^ permalink raw reply [flat|nested] 20+ messages in thread* Re: [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h
2019-08-28 2:47 ` [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Joe Perches
@ 2019-08-28 22:44 ` Nick Desaulniers
0 siblings, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-28 22:44 UTC (permalink / raw)
To: Joe Perches
Cc: Miguel Ojeda, Sedat Dilek, Will Deacon, Josh Poimboeuf,
naveen.n.rao, David S. Miller, Paul Burton, clang-built-linux,
LKML
On Tue, Aug 27, 2019 at 7:47 PM Joe Perches <joe@perches.com> wrote:
>
> On Tue, 2019-08-27 at 13:39 -0700, Nick Desaulniers wrote:
> > GCC unescapes escaped string section names while Clang does not. Because
> > __section uses the `#` stringification operator for the section name, it
> > doesn't need to be escaped.
> >
> > This fixes an Oops observed in distro's that use systemd and not
> > net.core.bpf_jit_enable=1, when their kernels are compiled with Clang.
> >
> > Instead, we should:
> > 1. Prefer __section(.section_name_no_quotes).
> > 2. Only use __attribute__((__section(".section"))) when creating the
>
> Please use __ before and after section
>
> i.e. __attribute__((__section__("<section_name>")))
>
>
*explitive*!!!
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 20+ messages in thread
* Re: [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h
2019-08-27 20:39 [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Nick Desaulniers
` (14 preceding siblings ...)
2019-08-28 2:47 ` [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h Joe Perches
@ 2019-08-28 9:59 ` Sedat Dilek
2019-08-28 22:44 ` Nick Desaulniers
2019-08-29 9:05 ` Sedat Dilek
15 siblings, 2 replies; 20+ messages in thread
From: Sedat Dilek @ 2019-08-28 9:59 UTC (permalink / raw)
To: Nick Desaulniers
Cc: Miguel Ojeda, will, jpoimboe, naveen.n.rao, davem, paul.burton,
Clang-Built-Linux ML, linux-kernel
On Tue, Aug 27, 2019 at 10:40 PM Nick Desaulniers
<ndesaulniers@google.com> wrote:
>
> GCC unescapes escaped string section names while Clang does not. Because
> __section uses the `#` stringification operator for the section name, it
> doesn't need to be escaped.
>
> This fixes an Oops observed in distro's that use systemd and not
> net.core.bpf_jit_enable=1, when their kernels are compiled with Clang.
>
> Instead, we should:
> 1. Prefer __section(.section_name_no_quotes).
> 2. Only use __attribute__((__section(".section"))) when creating the
> section name via C preprocessor (see the definition of __define_initcall
> in arch/um/include/shared/init.h).
>
> This antipattern was found with:
> $ grep -e __section\(\" -e __section__\(\" -r
>
Hi Nick,
thanks for the v2 of your patch-series.
I just checked v2 on top of Linux v5.3-rc6...
sdi@iniza:~/src/linux-kernel/linux$ grep -e __section\(\" -e __section__\(\" -r
include/linux/compiler_attributes.h: * __section(".foo")
include/linux/compiler_attributes.h: * verbose
__attribute__((__section__(".foo" x))) should be preferred.
OK: Description of the problem ^^
arch/sh/include/asm/cache.h:#define __read_mostly
__attribute__((__section__(".data..read_mostly")))
PATCH next-20190827 ^^
sh: prefer __section from compiler_attributes.h
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20190827&id=baf58858e8b6d853a7a8308901fcdd438e92a522
arch/arm64/kernel/smp_spin_table.c:volatile unsigned long
__section(".mmuoff.data.read")
arch/arm64/include/asm/cache.h:#define __read_mostly
__attribute__((__section__(".data..read_mostly")))
PATCH next-20190827 ^^
arm64: prefer __section from compiler_attributes.h
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?h=next-20190827&id=80d838122643a09a9f99824adea4b4261e4451e6
arch/um/include/shared/init.h: __attribute__((__section__(".initcall"
level ".init"))) = fn
??? ^^
> See the discussions in:
> https://bugs.llvm.org/show_bug.cgi?id=42950
> https://marc.info/?l=linux-netdev&m=156412960619946&w=2
>
List CBL issue tracker to discussions:
https://github.com/ClangBuiltLinux/linux/issues/619
- Sedat -
> Changes V1 -> V2:
> * drop arm64, arc, and sh patches as they were picked up by their
> maintainers.
> * Split the previous V1 hunk from include/linux that touched
> include/linux/compiler.h off into its own patch for inclusion in
> stable, as it fixes a user visible issue.
> * Collect Acks and Tested by tags.
>
> Nick Desaulniers (14):
> s390/boot: prefer __section from compiler_attributes.h
> include/linux/compiler.h: prefer __section from compiler_attributes.h
> parisc: prefer __section from compiler_attributes.h
> um: prefer __section from compiler_attributes.h
> ia64: prefer __section from compiler_attributes.h
> arm: prefer __section from compiler_attributes.h
> mips: prefer __section from compiler_attributes.h
> sparc: prefer __section from compiler_attributes.h
> powerpc: prefer __section and __printf from compiler_attributes.h
> x86: prefer __section from compiler_attributes.h
> include/asm-generic: prefer __section from compiler_attributes.h
> include/linux: prefer __section from compiler_attributes.h
> include/linux/compiler.h: remove unused KENTRY macro
> compiler_attributes.h: add note about __section
>
> arch/arm/include/asm/cache.h | 2 +-
> arch/arm/include/asm/mach/arch.h | 4 ++--
> arch/arm/include/asm/setup.h | 2 +-
> arch/ia64/include/asm/cache.h | 2 +-
> arch/mips/include/asm/cache.h | 2 +-
> arch/parisc/include/asm/cache.h | 2 +-
> arch/parisc/include/asm/ldcw.h | 2 +-
> arch/powerpc/boot/main.c | 3 +--
> arch/powerpc/boot/ps3.c | 6 ++----
> arch/powerpc/include/asm/cache.h | 2 +-
> arch/powerpc/kernel/btext.c | 2 +-
> arch/s390/boot/startup.c | 2 +-
> arch/sparc/include/asm/cache.h | 2 +-
> arch/sparc/kernel/btext.c | 2 +-
> arch/um/kernel/um_arch.c | 6 +++---
> arch/x86/include/asm/cache.h | 2 +-
> arch/x86/include/asm/intel-mid.h | 2 +-
> arch/x86/include/asm/iommu_table.h | 5 ++---
> arch/x86/include/asm/irqflags.h | 2 +-
> arch/x86/include/asm/mem_encrypt.h | 2 +-
> arch/x86/kernel/cpu/cpu.h | 3 +--
> include/asm-generic/error-injection.h | 2 +-
> include/asm-generic/kprobes.h | 5 ++---
> include/linux/cache.h | 6 +++---
> include/linux/compiler.h | 31 ++++-----------------------
> include/linux/compiler_attributes.h | 10 +++++++++
> include/linux/cpu.h | 2 +-
> include/linux/export.h | 2 +-
> include/linux/init_task.h | 4 ++--
> include/linux/interrupt.h | 5 ++---
> include/linux/sched/debug.h | 2 +-
> include/linux/srcutree.h | 2 +-
> 32 files changed, 54 insertions(+), 74 deletions(-)
>
> --
> 2.23.0.187.g17f5b7556c-goog
>
^ permalink raw reply [flat|nested] 20+ messages in thread* Re: [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h
2019-08-28 9:59 ` Sedat Dilek
@ 2019-08-28 22:44 ` Nick Desaulniers
2019-08-29 9:05 ` Sedat Dilek
1 sibling, 0 replies; 20+ messages in thread
From: Nick Desaulniers @ 2019-08-28 22:44 UTC (permalink / raw)
To: Sedat Dilek
Cc: Miguel Ojeda, Will Deacon, Josh Poimboeuf, naveen.n.rao,
David S. Miller, Paul Burton, Clang-Built-Linux ML, LKML
On Wed, Aug 28, 2019 at 3:00 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> On Tue, Aug 27, 2019 at 10:40 PM Nick Desaulniers
> <ndesaulniers@google.com> wrote:
> >
> > GCC unescapes escaped string section names while Clang does not. Because
> > __section uses the `#` stringification operator for the section name, it
> > doesn't need to be escaped.
> >
> > This fixes an Oops observed in distro's that use systemd and not
> > net.core.bpf_jit_enable=1, when their kernels are compiled with Clang.
> >
> > Instead, we should:
> > 1. Prefer __section(.section_name_no_quotes).
> > 2. Only use __attribute__((__section(".section"))) when creating the
> > section name via C preprocessor (see the definition of __define_initcall
> > in arch/um/include/shared/init.h).
Case 2 referenced below.
> >
> > This antipattern was found with:
> > $ grep -e __section\(\" -e __section__\(\" -r
> >
>
> Hi Nick,
>
> thanks for the v2 of your patch-series.
>
> I just checked v2 on top of Linux v5.3-rc6...
> arch/um/include/shared/init.h: __attribute__((__section__(".initcall"
> level ".init"))) = fn
>
> ??? ^^
Right, thanks for checking. That case is a section dynamically built
via preprocessor, so that's the case I'm referring to in case 2.
>
> > See the discussions in:
> > https://bugs.llvm.org/show_bug.cgi?id=42950
> > https://marc.info/?l=linux-netdev&m=156412960619946&w=2
> >
>
> List CBL issue tracker to discussions:
> https://github.com/ClangBuiltLinux/linux/issues/619
Will do in v3!
--
Thanks,
~Nick Desaulniers
^ permalink raw reply [flat|nested] 20+ messages in thread* Re: [PATCH v2 00/14] treewide: prefer __section from compiler_attributes.h
2019-08-28 9:59 ` Sedat Dilek
2019-08-28 22:44 ` Nick Desaulniers
@ 2019-08-29 9:05 ` Sedat Dilek
1 sibling, 0 replies; 20+ messages in thread
From: Sedat Dilek @ 2019-08-29 9:05 UTC (permalink / raw)
To: Nick Desaulniers
Cc: Miguel Ojeda, will, jpoimboe, naveen.n.rao, davem, paul.burton,
Clang-Built-Linux ML, linux-kernel
> $ grep -e __section\(\" -e __section__\(\" -r
>
> arch/um/include/shared/init.h: __attribute__((__section__(".initcall"
> level ".init"))) = fn
>
2. Only use __attribute__((__section__(".section"))) when creating the
section name via C preprocessor (see the definition of __define_initcall
in arch/um/include/shared/init.h).
Who reads commit messages?
/me hides
- Sedat -
^ permalink raw reply [flat|nested] 20+ messages in thread