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This helper is used to detect if a uprobe'd function has returned through a setjmp/longjmp, rather than branching to the LR that was updated previously by us. This fixes a SIGSEGV that gets generated when programs use setjmp/longjmp with uretprobes. We use the arm64 model (arch/arm64/kernel/probes/uprobes.c: arch_uretprobe_is_alive()) for detecting when stack frames have been removed from under us. Reference: https://marc.info/?l=linux-kernel&m=143748610330073 commit 7b868e4802a86 ("uprobes/x86: Reimplement arch_uretprobe_is_alive()") commit db087ef69a2b1 ("uprobes/x86: Make arch_uretprobe_is_alive(RP_CHECK_CALL) more clever") Tested with the test program from: https://sourceware.org/git/gitweb.cgi?p=systemtap.git;a=blob;f=testsuite/systemtap.base/bz5274.c;hb=HEAD And this script: $ cat test.sh #!/bin/bash perf probe -x ./bz5274 -a bz5274_main_return=main%return perf probe -x ./bz5274 -a bz5274_funca_return=funca%return perf probe -x ./bz5274 -a bz5274_funcb_return=funcb%return perf probe -x ./bz5274 -a bz5274_funcc_return=funcc%return perf probe -x ./bz5274 -a bz5274_funcd_return=funcd%return perf record -e 'probe_bz5274:*' -aR ./bz5274 Reported-by: Gustavo Luiz Duarte <gduarte@redhat.com> Reported-by: zsun@redhat.com Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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.