* [PATCH 1/3] scripts/recordmcount.pl: Fix RISC-V regex for clang
2021-03-25 22:38 [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang Nathan Chancellor
@ 2021-03-25 22:38 ` Nathan Chancellor
2021-03-25 23:36 ` Fangrui Song
2021-03-25 22:38 ` [PATCH 2/3] riscv: Workaround mcount name prior to clang-13 Nathan Chancellor
` (3 subsequent siblings)
4 siblings, 1 reply; 11+ messages in thread
From: Nathan Chancellor @ 2021-03-25 22:38 UTC (permalink / raw)
To: Palmer Dabbelt, Paul Walmsley, Albert Ou
Cc: linux-riscv, linux-kernel, clang-built-linux, Nathan Chancellor, stable
Clang can generate R_RISCV_CALL_PLT relocations to _mcount:
$ llvm-objdump -dr build/riscv/init/main.o | rg mcount
000000000000000e: R_RISCV_CALL_PLT _mcount
000000000000004e: R_RISCV_CALL_PLT _mcount
After this, the __start_mcount_loc section is properly generated and
function tracing still works.
Cc: stable@vger.kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/1331
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
scripts/recordmcount.pl | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index 867860ea57da..a36df04cfa09 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -392,7 +392,7 @@ if ($arch eq "x86_64") {
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
} elsif ($arch eq "riscv") {
$function_regex = "^([0-9a-fA-F]+)\\s+<([^.0-9][0-9a-zA-Z_\\.]+)>:";
- $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL\\s_mcount\$";
+ $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_mcount\$";
$type = ".quad";
$alignment = 2;
} elsif ($arch eq "nds32") {
--
2.31.0
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^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 1/3] scripts/recordmcount.pl: Fix RISC-V regex for clang
2021-03-25 22:38 ` [PATCH 1/3] scripts/recordmcount.pl: Fix RISC-V regex for clang Nathan Chancellor
@ 2021-03-25 23:36 ` Fangrui Song
0 siblings, 0 replies; 11+ messages in thread
From: Fangrui Song @ 2021-03-25 23:36 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Palmer Dabbelt, Paul Walmsley, Albert Ou, linux-riscv,
linux-kernel, clang-built-linux, stable
On 2021-03-25, Nathan Chancellor wrote:
>Clang can generate R_RISCV_CALL_PLT relocations to _mcount:
>
>$ llvm-objdump -dr build/riscv/init/main.o | rg mcount
> 000000000000000e: R_RISCV_CALL_PLT _mcount
> 000000000000004e: R_RISCV_CALL_PLT _mcount
>
>After this, the __start_mcount_loc section is properly generated and
>function tracing still works.
>
R_RISCV_CALL_PLT can replace R_RISCV_CALL in all use cases.
R_RISCV_CALL can/may be deprecated:
https://github.com/ClangBuiltLinux/linux/issues/1331#issuecomment-802468296
Reviewed-by: Fangrui Song <maskray@google.com>
>Cc: stable@vger.kernel.org
>Link: https://github.com/ClangBuiltLinux/linux/issues/1331
>Signed-off-by: Nathan Chancellor <nathan@kernel.org>
>---
> scripts/recordmcount.pl | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
>index 867860ea57da..a36df04cfa09 100755
>--- a/scripts/recordmcount.pl
>+++ b/scripts/recordmcount.pl
>@@ -392,7 +392,7 @@ if ($arch eq "x86_64") {
> $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
> } elsif ($arch eq "riscv") {
> $function_regex = "^([0-9a-fA-F]+)\\s+<([^.0-9][0-9a-zA-Z_\\.]+)>:";
>- $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL\\s_mcount\$";
>+ $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_mcount\$";
> $type = ".quad";
> $alignment = 2;
> } elsif ($arch eq "nds32") {
>--
>2.31.0
>
>--
>You received this message because you are subscribed to the Google Groups "Clang Built Linux" group.
>To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com.
>To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210325223807.2423265-2-nathan%40kernel.org.
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^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 2/3] riscv: Workaround mcount name prior to clang-13
2021-03-25 22:38 [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang Nathan Chancellor
2021-03-25 22:38 ` [PATCH 1/3] scripts/recordmcount.pl: Fix RISC-V regex for clang Nathan Chancellor
@ 2021-03-25 22:38 ` Nathan Chancellor
2021-03-29 18:32 ` Nick Desaulniers
2021-03-25 22:38 ` [PATCH 3/3] riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is available Nathan Chancellor
` (2 subsequent siblings)
4 siblings, 1 reply; 11+ messages in thread
From: Nathan Chancellor @ 2021-03-25 22:38 UTC (permalink / raw)
To: Palmer Dabbelt, Paul Walmsley, Albert Ou
Cc: linux-riscv, linux-kernel, clang-built-linux, Nathan Chancellor, stable
Prior to clang 13.0.0, the RISC-V name for the mcount symbol was
"mcount", which differs from the GCC version of "_mcount", which results
in the following errors:
riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_level':
main.c:(.text+0xe): undefined reference to `mcount'
riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_start':
main.c:(.text+0x4e): undefined reference to `mcount'
riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_finish':
main.c:(.text+0x92): undefined reference to `mcount'
riscv64-linux-gnu-ld: init/main.o: in function `.LBB32_28':
main.c:(.text+0x30c): undefined reference to `mcount'
riscv64-linux-gnu-ld: init/main.o: in function `free_initmem':
main.c:(.text+0x54c): undefined reference to `mcount'
This has been corrected in https://reviews.llvm.org/D98881 but the
minimum supported clang version is 10.0.1. To avoid build errors and to
gain a working function tracer, adjust the name of the mcount symbol for
older versions of clang in mount.S and recordmcount.pl.
Cc: stable@vger.kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/1331
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
arch/riscv/include/asm/ftrace.h | 14 ++++++++++++--
arch/riscv/kernel/mcount.S | 10 +++++-----
scripts/recordmcount.pl | 2 +-
3 files changed, 18 insertions(+), 8 deletions(-)
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 845002cc2e57..04dad3380041 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -13,9 +13,19 @@
#endif
#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
+/*
+ * Clang prior to 13 had "mcount" instead of "_mcount":
+ * https://reviews.llvm.org/D98881
+ */
+#if defined(CONFIG_CC_IS_GCC) || CONFIG_CLANG_VERSION >= 130000
+#define MCOUNT_NAME _mcount
+#else
+#define MCOUNT_NAME mcount
+#endif
+
#define ARCH_SUPPORTS_FTRACE_OPS 1
#ifndef __ASSEMBLY__
-void _mcount(void);
+void MCOUNT_NAME(void);
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
return addr;
@@ -36,7 +46,7 @@ struct dyn_arch_ftrace {
* both auipc and jalr at the same time.
*/
-#define MCOUNT_ADDR ((unsigned long)_mcount)
+#define MCOUNT_ADDR ((unsigned long)MCOUNT_NAME)
#define JALR_SIGN_MASK (0x00000800)
#define JALR_OFFSET_MASK (0x00000fff)
#define AUIPC_OFFSET_MASK (0xfffff000)
diff --git a/arch/riscv/kernel/mcount.S b/arch/riscv/kernel/mcount.S
index 8a5593ff9ff3..6d462681c9c0 100644
--- a/arch/riscv/kernel/mcount.S
+++ b/arch/riscv/kernel/mcount.S
@@ -47,8 +47,8 @@
ENTRY(ftrace_stub)
#ifdef CONFIG_DYNAMIC_FTRACE
- .global _mcount
- .set _mcount, ftrace_stub
+ .global MCOUNT_NAME
+ .set MCOUNT_NAME, ftrace_stub
#endif
ret
ENDPROC(ftrace_stub)
@@ -78,7 +78,7 @@ ENDPROC(return_to_handler)
#endif
#ifndef CONFIG_DYNAMIC_FTRACE
-ENTRY(_mcount)
+ENTRY(MCOUNT_NAME)
la t4, ftrace_stub
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
la t0, ftrace_graph_return
@@ -124,6 +124,6 @@ do_trace:
jalr t5
RESTORE_ABI_STATE
ret
-ENDPROC(_mcount)
+ENDPROC(MCOUNT_NAME)
#endif
-EXPORT_SYMBOL(_mcount)
+EXPORT_SYMBOL(MCOUNT_NAME)
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index a36df04cfa09..7b83a1aaec98 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -392,7 +392,7 @@ if ($arch eq "x86_64") {
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
} elsif ($arch eq "riscv") {
$function_regex = "^([0-9a-fA-F]+)\\s+<([^.0-9][0-9a-zA-Z_\\.]+)>:";
- $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_mcount\$";
+ $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_?mcount\$";
$type = ".quad";
$alignment = 2;
} elsif ($arch eq "nds32") {
--
2.31.0
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 2/3] riscv: Workaround mcount name prior to clang-13
2021-03-25 22:38 ` [PATCH 2/3] riscv: Workaround mcount name prior to clang-13 Nathan Chancellor
@ 2021-03-29 18:32 ` Nick Desaulniers
0 siblings, 0 replies; 11+ messages in thread
From: Nick Desaulniers @ 2021-03-29 18:32 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Palmer Dabbelt, Paul Walmsley, Albert Ou, linux-riscv, LKML,
clang-built-linux, # 3.4.x
On Thu, Mar 25, 2021 at 3:38 PM Nathan Chancellor <nathan@kernel.org> wrote:
>
> Prior to clang 13.0.0, the RISC-V name for the mcount symbol was
> "mcount", which differs from the GCC version of "_mcount", which results
> in the following errors:
>
> riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_level':
> main.c:(.text+0xe): undefined reference to `mcount'
> riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_start':
> main.c:(.text+0x4e): undefined reference to `mcount'
> riscv64-linux-gnu-ld: init/main.o: in function `__traceiter_initcall_finish':
> main.c:(.text+0x92): undefined reference to `mcount'
> riscv64-linux-gnu-ld: init/main.o: in function `.LBB32_28':
> main.c:(.text+0x30c): undefined reference to `mcount'
> riscv64-linux-gnu-ld: init/main.o: in function `free_initmem':
> main.c:(.text+0x54c): undefined reference to `mcount'
>
> This has been corrected in https://reviews.llvm.org/D98881 but the
> minimum supported clang version is 10.0.1. To avoid build errors and to
> gain a working function tracer, adjust the name of the mcount symbol for
> older versions of clang in mount.S and recordmcount.pl.
>
> Cc: stable@vger.kernel.org
> Link: https://github.com/ClangBuiltLinux/linux/issues/1331
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Thanks for keeping this alive on clang-10, and resolving it for future releases!
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> ---
> arch/riscv/include/asm/ftrace.h | 14 ++++++++++++--
> arch/riscv/kernel/mcount.S | 10 +++++-----
> scripts/recordmcount.pl | 2 +-
> 3 files changed, 18 insertions(+), 8 deletions(-)
>
> diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
> index 845002cc2e57..04dad3380041 100644
> --- a/arch/riscv/include/asm/ftrace.h
> +++ b/arch/riscv/include/asm/ftrace.h
> @@ -13,9 +13,19 @@
> #endif
> #define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
>
> +/*
> + * Clang prior to 13 had "mcount" instead of "_mcount":
> + * https://reviews.llvm.org/D98881
> + */
> +#if defined(CONFIG_CC_IS_GCC) || CONFIG_CLANG_VERSION >= 130000
> +#define MCOUNT_NAME _mcount
> +#else
> +#define MCOUNT_NAME mcount
> +#endif
> +
> #define ARCH_SUPPORTS_FTRACE_OPS 1
> #ifndef __ASSEMBLY__
> -void _mcount(void);
> +void MCOUNT_NAME(void);
> static inline unsigned long ftrace_call_adjust(unsigned long addr)
> {
> return addr;
> @@ -36,7 +46,7 @@ struct dyn_arch_ftrace {
> * both auipc and jalr at the same time.
> */
>
> -#define MCOUNT_ADDR ((unsigned long)_mcount)
> +#define MCOUNT_ADDR ((unsigned long)MCOUNT_NAME)
> #define JALR_SIGN_MASK (0x00000800)
> #define JALR_OFFSET_MASK (0x00000fff)
> #define AUIPC_OFFSET_MASK (0xfffff000)
> diff --git a/arch/riscv/kernel/mcount.S b/arch/riscv/kernel/mcount.S
> index 8a5593ff9ff3..6d462681c9c0 100644
> --- a/arch/riscv/kernel/mcount.S
> +++ b/arch/riscv/kernel/mcount.S
> @@ -47,8 +47,8 @@
>
> ENTRY(ftrace_stub)
> #ifdef CONFIG_DYNAMIC_FTRACE
> - .global _mcount
> - .set _mcount, ftrace_stub
> + .global MCOUNT_NAME
> + .set MCOUNT_NAME, ftrace_stub
> #endif
> ret
> ENDPROC(ftrace_stub)
> @@ -78,7 +78,7 @@ ENDPROC(return_to_handler)
> #endif
>
> #ifndef CONFIG_DYNAMIC_FTRACE
> -ENTRY(_mcount)
> +ENTRY(MCOUNT_NAME)
> la t4, ftrace_stub
> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
> la t0, ftrace_graph_return
> @@ -124,6 +124,6 @@ do_trace:
> jalr t5
> RESTORE_ABI_STATE
> ret
> -ENDPROC(_mcount)
> +ENDPROC(MCOUNT_NAME)
> #endif
> -EXPORT_SYMBOL(_mcount)
> +EXPORT_SYMBOL(MCOUNT_NAME)
> diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
> index a36df04cfa09..7b83a1aaec98 100755
> --- a/scripts/recordmcount.pl
> +++ b/scripts/recordmcount.pl
> @@ -392,7 +392,7 @@ if ($arch eq "x86_64") {
> $mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
> } elsif ($arch eq "riscv") {
> $function_regex = "^([0-9a-fA-F]+)\\s+<([^.0-9][0-9a-zA-Z_\\.]+)>:";
> - $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_mcount\$";
> + $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_?mcount\$";
> $type = ".quad";
> $alignment = 2;
> } elsif ($arch eq "nds32") {
> --
> 2.31.0
>
> --
> You received this message because you are subscribed to the Google Groups "Clang Built Linux" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210325223807.2423265-3-nathan%40kernel.org.
--
Thanks,
~Nick Desaulniers
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^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH 3/3] riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is available
2021-03-25 22:38 [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang Nathan Chancellor
2021-03-25 22:38 ` [PATCH 1/3] scripts/recordmcount.pl: Fix RISC-V regex for clang Nathan Chancellor
2021-03-25 22:38 ` [PATCH 2/3] riscv: Workaround mcount name prior to clang-13 Nathan Chancellor
@ 2021-03-25 22:38 ` Nathan Chancellor
2021-03-25 23:38 ` Fangrui Song
2021-03-26 8:37 ` [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang Sedat Dilek
2021-04-11 21:27 ` Palmer Dabbelt
4 siblings, 1 reply; 11+ messages in thread
From: Nathan Chancellor @ 2021-03-25 22:38 UTC (permalink / raw)
To: Palmer Dabbelt, Paul Walmsley, Albert Ou
Cc: linux-riscv, linux-kernel, clang-built-linux, Nathan Chancellor,
kernel test robot
clang prior to 13.0.0 does not support -fpatchable-function-entry for
RISC-V.
clang: error: unsupported option '-fpatchable-function-entry=8' for target 'riscv64-unknown-linux-gnu'
To avoid this error, only select HAVE_DYNAMIC_FTRACE when this option is
not available.
Fixes: afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT")
Link: https://github.com/ClangBuiltLinux/linux/issues/1268
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
arch/riscv/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 87d7b52f278f..ba1d07640b66 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -227,7 +227,7 @@ config ARCH_RV64I
bool "RV64I"
select 64BIT
select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 && GCC_VERSION >= 50000
- select HAVE_DYNAMIC_FTRACE if MMU
+ select HAVE_DYNAMIC_FTRACE if MMU && $(cc-option,-fpatchable-function-entry=8)
select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
select HAVE_FTRACE_MCOUNT_RECORD
select HAVE_FUNCTION_GRAPH_TRACER
--
2.31.0
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^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH 3/3] riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is available
2021-03-25 22:38 ` [PATCH 3/3] riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is available Nathan Chancellor
@ 2021-03-25 23:38 ` Fangrui Song
0 siblings, 0 replies; 11+ messages in thread
From: Fangrui Song @ 2021-03-25 23:38 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Palmer Dabbelt, Paul Walmsley, Albert Ou, linux-riscv,
linux-kernel, clang-built-linux, kernel test robot
On 2021-03-25, Nathan Chancellor wrote:
>clang prior to 13.0.0 does not support -fpatchable-function-entry for
>RISC-V.
>
>clang: error: unsupported option '-fpatchable-function-entry=8' for target 'riscv64-unknown-linux-gnu'
>
>To avoid this error, only select HAVE_DYNAMIC_FTRACE when this option is
>not available.
If clang -fpatchable-function-entry=8 does not error "unsupported
option" for one target, it means the backend feature is supported on
this target.
Reviewed-by: Fangrui Song <maskray@google.com>
>Fixes: afc76b8b8011 ("riscv: Using PATCHABLE_FUNCTION_ENTRY instead of MCOUNT")
>Link: https://github.com/ClangBuiltLinux/linux/issues/1268
>Reported-by: kernel test robot <lkp@intel.com>
>Signed-off-by: Nathan Chancellor <nathan@kernel.org>
>---
> arch/riscv/Kconfig | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>index 87d7b52f278f..ba1d07640b66 100644
>--- a/arch/riscv/Kconfig
>+++ b/arch/riscv/Kconfig
>@@ -227,7 +227,7 @@ config ARCH_RV64I
> bool "RV64I"
> select 64BIT
> select ARCH_SUPPORTS_INT128 if CC_HAS_INT128 && GCC_VERSION >= 50000
>- select HAVE_DYNAMIC_FTRACE if MMU
>+ select HAVE_DYNAMIC_FTRACE if MMU && $(cc-option,-fpatchable-function-entry=8)
> select HAVE_DYNAMIC_FTRACE_WITH_REGS if HAVE_DYNAMIC_FTRACE
> select HAVE_FTRACE_MCOUNT_RECORD
> select HAVE_FUNCTION_GRAPH_TRACER
>--
>2.31.0
>
>--
>You received this message because you are subscribed to the Google Groups "Clang Built Linux" group.
>To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com.
>To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210325223807.2423265-4-nathan%40kernel.org.
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^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang
2021-03-25 22:38 [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang Nathan Chancellor
` (2 preceding siblings ...)
2021-03-25 22:38 ` [PATCH 3/3] riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is available Nathan Chancellor
@ 2021-03-26 8:37 ` Sedat Dilek
2021-03-26 13:07 ` Nathan Chancellor
2021-04-11 21:27 ` Palmer Dabbelt
4 siblings, 1 reply; 11+ messages in thread
From: Sedat Dilek @ 2021-03-26 8:37 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Palmer Dabbelt, Paul Walmsley, Albert Ou, linux-riscv,
linux-kernel, Clang-Built-Linux ML
On Thu, Mar 25, 2021 at 11:38 PM Nathan Chancellor <nathan@kernel.org> wrote:
>
> Hi all,
>
> This series fixes function tracing with clang.
>
> Patch 1 adjusts the mcount regex in scripts/recordmcount.pl to handle
> the presence of PLT relocations, which happen with clang. Without this,
> the mcount_loc section will not be created properly.
>
> Patch 2 adds a workaround for clang less than 13.0.0 in relation to the
> mcount symbol name, which was "mcount" rather than "_mcount". This was
> written as a separate patch so that it can be reverted when the minimum
> clang version is bumped to clang 13.0.0.
>
> Patch 3 avoids a build error when -fpatchable-function-entry is not
> available, which is the case with clang less than 13.0.0. This will make
> dynamic ftrace unavailable but all of the other function tracing should
> work due to the prescence of the previous patch.
>
> I am hoping this series can go in as fixes for 5.12, due to patch 3, but
> if not, they can always be backported (patches 1 and 2 are already
> marked for stable).
>
> This series has been build tested with gcc-8 through gcc-10 and clang-11
> through clang-13 with defconfig and nommu_virt_defconfig plus
> CONFIG_FTRACE=y and CONFIG_FUNCTION_TRACER=y then boot tested under
> QEMU.
>
> Cheers,
> Nathan
>
> Nathan Chancellor (3):
> scripts/recordmcount.pl: Fix RISC-V regex for clang
> riscv: Workaround mcount name prior to clang-13
> riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is
> available
>
Does this only fixes stuff for clang + riscv?
If so, please put a label "riscv" also in the cover-letter.
- Sedat -
> arch/riscv/Kconfig | 2 +-
> arch/riscv/include/asm/ftrace.h | 14 ++++++++++++--
> arch/riscv/kernel/mcount.S | 10 +++++-----
> scripts/recordmcount.pl | 2 +-
> 4 files changed, 19 insertions(+), 9 deletions(-)
>
> --
> 2.31.0
>
> --
> You received this message because you are subscribed to the Google Groups "Clang Built Linux" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210325223807.2423265-1-nathan%40kernel.org.
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^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang
2021-03-26 8:37 ` [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang Sedat Dilek
@ 2021-03-26 13:07 ` Nathan Chancellor
2021-03-27 12:16 ` Sedat Dilek
0 siblings, 1 reply; 11+ messages in thread
From: Nathan Chancellor @ 2021-03-26 13:07 UTC (permalink / raw)
To: Sedat Dilek
Cc: Palmer Dabbelt, Paul Walmsley, Albert Ou, linux-riscv,
linux-kernel, Clang-Built-Linux ML
On Fri, Mar 26, 2021 at 09:37:55AM +0100, Sedat Dilek wrote:
> On Thu, Mar 25, 2021 at 11:38 PM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > Hi all,
> >
> > This series fixes function tracing with clang.
> >
> > Patch 1 adjusts the mcount regex in scripts/recordmcount.pl to handle
> > the presence of PLT relocations, which happen with clang. Without this,
> > the mcount_loc section will not be created properly.
> >
> > Patch 2 adds a workaround for clang less than 13.0.0 in relation to the
> > mcount symbol name, which was "mcount" rather than "_mcount". This was
> > written as a separate patch so that it can be reverted when the minimum
> > clang version is bumped to clang 13.0.0.
> >
> > Patch 3 avoids a build error when -fpatchable-function-entry is not
> > available, which is the case with clang less than 13.0.0. This will make
> > dynamic ftrace unavailable but all of the other function tracing should
> > work due to the prescence of the previous patch.
> >
> > I am hoping this series can go in as fixes for 5.12, due to patch 3, but
> > if not, they can always be backported (patches 1 and 2 are already
> > marked for stable).
> >
> > This series has been build tested with gcc-8 through gcc-10 and clang-11
> > through clang-13 with defconfig and nommu_virt_defconfig plus
> > CONFIG_FTRACE=y and CONFIG_FUNCTION_TRACER=y then boot tested under
> > QEMU.
> >
> > Cheers,
> > Nathan
> >
> > Nathan Chancellor (3):
> > scripts/recordmcount.pl: Fix RISC-V regex for clang
> > riscv: Workaround mcount name prior to clang-13
> > riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is
> > available
> >
>
> Does this only fixes stuff for clang + riscv?
Yes.
> If so, please put a label "riscv" also in the cover-letter.
Sure, my apologies for not doing that in the first place, I must have
been in a rush with the cover letter.
In my defense, I think the titles of my commit messages and the diffstat
below make that obvious without the tag :)
Cheers,
Nathan
> - Sedat -
>
> > arch/riscv/Kconfig | 2 +-
> > arch/riscv/include/asm/ftrace.h | 14 ++++++++++++--
> > arch/riscv/kernel/mcount.S | 10 +++++-----
> > scripts/recordmcount.pl | 2 +-
> > 4 files changed, 19 insertions(+), 9 deletions(-)
> >
> > --
> > 2.31.0
> >
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^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang
2021-03-26 13:07 ` Nathan Chancellor
@ 2021-03-27 12:16 ` Sedat Dilek
0 siblings, 0 replies; 11+ messages in thread
From: Sedat Dilek @ 2021-03-27 12:16 UTC (permalink / raw)
To: Nathan Chancellor
Cc: Palmer Dabbelt, Paul Walmsley, Albert Ou, linux-riscv,
linux-kernel, Clang-Built-Linux ML
On Fri, Mar 26, 2021 at 2:07 PM Nathan Chancellor <nathan@kernel.org> wrote:
>
> On Fri, Mar 26, 2021 at 09:37:55AM +0100, Sedat Dilek wrote:
> > On Thu, Mar 25, 2021 at 11:38 PM Nathan Chancellor <nathan@kernel.org> wrote:
> > >
> > > Hi all,
> > >
> > > This series fixes function tracing with clang.
> > >
> > > Patch 1 adjusts the mcount regex in scripts/recordmcount.pl to handle
> > > the presence of PLT relocations, which happen with clang. Without this,
> > > the mcount_loc section will not be created properly.
> > >
> > > Patch 2 adds a workaround for clang less than 13.0.0 in relation to the
> > > mcount symbol name, which was "mcount" rather than "_mcount". This was
> > > written as a separate patch so that it can be reverted when the minimum
> > > clang version is bumped to clang 13.0.0.
> > >
> > > Patch 3 avoids a build error when -fpatchable-function-entry is not
> > > available, which is the case with clang less than 13.0.0. This will make
> > > dynamic ftrace unavailable but all of the other function tracing should
> > > work due to the prescence of the previous patch.
> > >
> > > I am hoping this series can go in as fixes for 5.12, due to patch 3, but
> > > if not, they can always be backported (patches 1 and 2 are already
> > > marked for stable).
> > >
> > > This series has been build tested with gcc-8 through gcc-10 and clang-11
> > > through clang-13 with defconfig and nommu_virt_defconfig plus
> > > CONFIG_FTRACE=y and CONFIG_FUNCTION_TRACER=y then boot tested under
> > > QEMU.
> > >
> > > Cheers,
> > > Nathan
> > >
> > > Nathan Chancellor (3):
> > > scripts/recordmcount.pl: Fix RISC-V regex for clang
> > > riscv: Workaround mcount name prior to clang-13
> > > riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is
> > > available
> > >
> >
> > Does this only fixes stuff for clang + riscv?
>
> Yes.
>
> > If so, please put a label "riscv" also in the cover-letter.
>
> Sure, my apologies for not doing that in the first place, I must have
> been in a rush with the cover letter.
>
> In my defense, I think the titles of my commit messages and the diffstat
> below make that obvious without the tag :)
>
No need for any apologies.
I was fooled as you sent two triple-patchset nearly simultaneously.
This riscv patchset here was not of interest to me.
- Sedat -
>
> > - Sedat -
> >
> > > arch/riscv/Kconfig | 2 +-
> > > arch/riscv/include/asm/ftrace.h | 14 ++++++++++++--
> > > arch/riscv/kernel/mcount.S | 10 +++++-----
> > > scripts/recordmcount.pl | 2 +-
> > > 4 files changed, 19 insertions(+), 9 deletions(-)
> > >
> > > --
> > > 2.31.0
> > >
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http://lists.infradead.org/mailman/listinfo/linux-riscv
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang
2021-03-25 22:38 [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang Nathan Chancellor
` (3 preceding siblings ...)
2021-03-26 8:37 ` [PATCH 0/3] Fix CONFIG_FUNCTION_TRACER with clang Sedat Dilek
@ 2021-04-11 21:27 ` Palmer Dabbelt
4 siblings, 0 replies; 11+ messages in thread
From: Palmer Dabbelt @ 2021-04-11 21:27 UTC (permalink / raw)
To: nathan
Cc: Paul Walmsley, aou, linux-riscv, linux-kernel, clang-built-linux, nathan
On Thu, 25 Mar 2021 15:38:04 PDT (-0700), nathan@kernel.org wrote:
> Hi all,
>
> This series fixes function tracing with clang.
>
> Patch 1 adjusts the mcount regex in scripts/recordmcount.pl to handle
> the presence of PLT relocations, which happen with clang. Without this,
> the mcount_loc section will not be created properly.
>
> Patch 2 adds a workaround for clang less than 13.0.0 in relation to the
> mcount symbol name, which was "mcount" rather than "_mcount". This was
> written as a separate patch so that it can be reverted when the minimum
> clang version is bumped to clang 13.0.0.
>
> Patch 3 avoids a build error when -fpatchable-function-entry is not
> available, which is the case with clang less than 13.0.0. This will make
> dynamic ftrace unavailable but all of the other function tracing should
> work due to the prescence of the previous patch.
>
> I am hoping this series can go in as fixes for 5.12, due to patch 3, but
> if not, they can always be backported (patches 1 and 2 are already
> marked for stable).
>
> This series has been build tested with gcc-8 through gcc-10 and clang-11
> through clang-13 with defconfig and nommu_virt_defconfig plus
> CONFIG_FTRACE=y and CONFIG_FUNCTION_TRACER=y then boot tested under
> QEMU.
>
> Cheers,
> Nathan
>
> Nathan Chancellor (3):
> scripts/recordmcount.pl: Fix RISC-V regex for clang
> riscv: Workaround mcount name prior to clang-13
> riscv: Select HAVE_DYNAMIC_FTRACE when -fpatchable-function-entry is
> available
>
> arch/riscv/Kconfig | 2 +-
> arch/riscv/include/asm/ftrace.h | 14 ++++++++++++--
> arch/riscv/kernel/mcount.S | 10 +++++-----
> scripts/recordmcount.pl | 2 +-
> 4 files changed, 19 insertions(+), 9 deletions(-)
Thanks, these are on for-next.
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^ permalink raw reply [flat|nested] 11+ messages in thread