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| author | Mark Rutland <mark.rutland@arm.com> | 2023-02-27 11:58:19 +0000 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2023-02-28 10:04:53 +0000 |
| commit | b3f11af9b2ce14d4662753d097a21e1d37a06fda (patch) | |
| tree | 9048246847398ad970eedd3d68f153eb1b177d6b | |
| parent | 1b561d3949f8478c5403c9752b5533211a757226 (diff) | |
| download | linux-andi-b3f11af9b2ce14d4662753d097a21e1d37a06fda.tar.gz | |
arm64: ftrace: forbid CALL_OPS with CC_OPTIMIZE_FOR_SIZE
Florian reports that when building with CONFIG_CC_OPTIMIZE_FOR_SIZE=y,
he sees "Misaligned patch-site" warnings at boot, e.g.
| Misaligned patch-site bcm2836_arm_irqchip_handle_irq+0x0/0x88
| WARNING: CPU: 0 PID: 0 at arch/arm64/kernel/ftrace.c:120 ftrace_call_adjust+0x4c/0x70
This is because GCC will silently ignore `-falign-functions=N` when
passed `-Os`, resulting in functions not being aligned as we expect.
This is a known issue, and to account for this we modified the kernel to
avoid `-Os` generally. Unfortunately we forgot to account for
CONFIG_CC_OPTIMIZE_FOR_SIZE.
Forbid the use of CALL_OPS with CONFIG_CC_OPTIMIZE_FOR_SIZE=y to prevent
this issue. All exising ftrace features will work as before, though
without the performance benefit of CALL_OPS.
Reported-by: Florian Fainelli <f.fainelli@gmail.com>
Link: http://lore.kernel.org/linux-arm-kernel/2d9284c3-3805-402b-5423-520ced56d047@gmail.com
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Stefan Wahren <stefan.wahren@i2se.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Will Deacon <will@kernel.org>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20230227115819.365630-1-mark.rutland@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
| -rw-r--r-- | arch/arm64/Kconfig | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 71c35178e017dd..f7521695a47420 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -188,7 +188,8 @@ config ARM64 select HAVE_DYNAMIC_FTRACE_WITH_ARGS \ if $(cc-option,-fpatchable-function-entry=2) select HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS \ - if (DYNAMIC_FTRACE_WITH_ARGS && !CFI_CLANG) + if (DYNAMIC_FTRACE_WITH_ARGS && !CFI_CLANG && \ + !CC_OPTIMIZE_FOR_SIZE) select FTRACE_MCOUNT_USE_PATCHABLE_FUNCTION_ENTRY \ if DYNAMIC_FTRACE_WITH_ARGS select HAVE_EFFICIENT_UNALIGNED_ACCESS |