764929accf
commit 923510c88d2b7d947c4217835fd9ca6bd65cc56c upstream. Clang likes to create conditional tail calls like: 0000000000000350 <amd_pmu_add_event>: 350: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 351: R_X86_64_NONE __fentry__-0x4 355: 48 83 bf 20 01 00 00 00 cmpq $0x0,0x120(%rdi) 35d: 0f 85 00 00 00 00 jne 363 <amd_pmu_add_event+0x13> 35f: R_X86_64_PLT32 __SCT__amd_pmu_branch_add-0x4 363: e9 00 00 00 00 jmp 368 <amd_pmu_add_event+0x18> 364: R_X86_64_PLT32 __x86_return_thunk-0x4 Where 0x35d is a static call site that's turned into a conditional tail-call using the Jcc class of instructions. Teach the in-line static call text patching about this. Notably, since there is no conditional-ret, in that case patch the Jcc to point at an empty stub function that does the ret -- or the return thunk when needed. Reported-by: "Erhard F." <erhard_f@mailbox.org> Change-Id: I99c8fc3f721e5d1c74f06710b38d4bac5230303a Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Link: https://lore.kernel.org/r/Y9Kdg9QjHkr9G5b5@hirez.programming.kicks-ass.net [cascardo: __static_call_validate didn't have the bool tramp argument] Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.