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ftrace: Have architectures opt-in for mcount build time sorting

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First S390 complained that the sorting of the mcount sections at build
time caused the kernel to crash on their architecture. Now PowerPC is
complaining about it too. And also ARM64 appears to be having issues.

It may be necessary to also update the relocation table for the values
in the mcount table. Not only do we have to sort the table, but also
update the relocations that may be applied to the items in the table.

If the system is not relocatable, then it is fine to sort, but if it is,
some architectures may have issues (although x86 does not as it shifts all
addresses the same).

Add a HAVE_BUILDTIME_MCOUNT_SORT that an architecture can set to say it is
safe to do the sorting at build time.

Also update the config to compile in build time sorting in the sorttable
code in scripts/ to depend on CONFIG_BUILDTIME_MCOUNT_SORT.

Link: https://lore.kernel.org/all/944D10DA-8200-4BA9-8D0A-3BED9AA99F82@linux.ibm.com/
Link: https://lkml.kernel.org/r/20220127153821.3bc1ac6e@gandalf.local.home

Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Yinan Liu <yinan@linux.alibaba.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Reported-by: Sachin Sant <sachinp@linux.ibm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com> [arm64]
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
Fixes: 72b3942a17 ("scripts: ftrace - move the sort-processing in ftrace_init")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Google) 2022-01-25 09:19:10 -05:00
parent e783362eb5
commit 4ed308c445
4 changed files with 10 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/arm/Kconfig
View File

@ -83,6 +83,7 @@ config ARM
select HAVE_EBPF_JIT if !CPU_ENDIAN_BE32
select HAVE_CONTEXT_TRACKING
select HAVE_C_RECORDMCOUNT
select HAVE_BUILDTIME_MCOUNT_SORT
select HAVE_DEBUG_KMEMLEAK if !XIP_KERNEL
select HAVE_DMA_CONTIGUOUS if MMU
select HAVE_DYNAMIC_FTRACE if !XIP_KERNEL && !CPU_ENDIAN_BE32 && MMU

1
arch/x86/Kconfig
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@ -186,6 +186,7 @@ config X86
select HAVE_CONTEXT_TRACKING_OFFSTACK if HAVE_CONTEXT_TRACKING
select HAVE_C_RECORDMCOUNT
select HAVE_OBJTOOL_MCOUNT if STACK_VALIDATION
select HAVE_BUILDTIME_MCOUNT_SORT
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_CONTIGUOUS
select HAVE_DYNAMIC_FTRACE

8
kernel/trace/Kconfig
View File

@ -70,10 +70,16 @@ config HAVE_C_RECORDMCOUNT
help
C version of recordmcount available?
config HAVE_BUILDTIME_MCOUNT_SORT
bool
help
An architecture selects this if it sorts the mcount_loc section
at build time.
config BUILDTIME_MCOUNT_SORT
bool
default y
depends on BUILDTIME_TABLE_SORT && !S390
depends on HAVE_BUILDTIME_MCOUNT_SORT && DYNAMIC_FTRACE
help
Sort the mcount_loc section at build time.

2
scripts/Makefile
View File

@ -25,7 +25,7 @@ HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/x86/include
HOSTCFLAGS_sorttable.o += -DUNWINDER_ORC_ENABLED
endif
ifdef CONFIG_DYNAMIC_FTRACE
ifdef CONFIG_BUILDTIME_MCOUNT_SORT
HOSTCFLAGS_sorttable.o += -DMCOUNT_SORT_ENABLED
endif