129f6c4820
When XIP_KERNEL is enabled, some functions are defined in the .data ELF section because we require them to be in RAM whenever we communicate with the flash chip. However this causes problems when FTRACE is enabled and gcc emits calls to __gnu_mcount_nc in the function prolog: drivers/built-in.o: In function `cfi_chip_setup': :(.data+0x272fc): relocation truncated to fit: R_ARM_CALL against symbol `__gnu_mcount_nc' defined in .text section in arch/arm/kernel/built-in.o drivers/built-in.o: In function `cfi_probe_chip': :(.data+0x27de8): relocation truncated to fit: R_ARM_CALL against symbol `__gnu_mcount_nc' defined in .text section in arch/arm/kernel/built-in.o /tmp/ccY172rP.s: Assembler messages: /tmp/ccY172rP.s:70: Warning: ignoring changed section attributes for .data /tmp/ccY172rP.s: Error: 1 warning, treating warnings as errors make[5]: *** [drivers/mtd/chips/cfi_probe.o] Error 1 /tmp/ccK4rjeO.s: Assembler messages: /tmp/ccK4rjeO.s:421: Warning: ignoring changed section attributes for .data /tmp/ccK4rjeO.s: Error: 1 warning, treating warnings as errors make[5]: *** [drivers/mtd/chips/cfi_util.o] Error 1 /tmp/ccUvhCYR.s: Assembler messages: /tmp/ccUvhCYR.s:1895: Warning: ignoring changed section attributes for .data /tmp/ccUvhCYR.s: Error: 1 warning, treating warnings as errors Specifically, this does not work because the .data section is not marked executable, which leads LD to not generate trampolines for long calls. This moves the __xipram functions into their own .xiptext section instead. The section is still placed next to .data and located in RAM but is marked executable, which avoids the build errors. Also, we only need to place the XIP functions into a separate section if both CONFIG_XIP_KERNEL and CONFIG_MTD_XIP are set: When only MTD_XIP is used, the whole kernel is still in RAM and we do not need to worry about pulling out the rug under it. When only XIP_KERNEL but not MTD_XIP is set, the kernel is in some form of ROM, but we never write to it. Note that MTD_XIP has been broken on ARM since around 2011 or 2012. I have sent another patch[2] to fix compilation, which I plan to merge through arm-soc unless there are objections. The obvious alternative to that would be to completely rip out the MTD_XIP support from the kernel, since obviously nobody has been using it in a long while. Link: [1] https://patchwork.kernel.org/patch/8109771/ Link: [2] https://patchwork.kernel.org/patch/9855225/ Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> |
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| drivers | ||
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| fs | ||
| include | ||
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| ipc | ||
| kernel | ||
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| samples | ||
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.