From 2dea1d9c38e481051fa0e62807e518c5768e62dd Mon Sep 17 00:00:00 2001 From: "Naveen N. Rao" Date: Wed, 14 Jun 2017 21:14:00 +0530 Subject: [PATCH] powerpc/uprobes: Implement arch_uretprobe_is_alive() 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 Reported-by: zsun@redhat.com Signed-off-by: Naveen N. Rao Acked-by: Srikar Dronamraju Signed-off-by: Michael Ellerman --- arch/powerpc/kernel/uprobes.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c index 003b20964ea0..5d105b8eeece 100644 --- a/arch/powerpc/kernel/uprobes.c +++ b/arch/powerpc/kernel/uprobes.c @@ -205,3 +205,12 @@ arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs return orig_ret_vaddr; } + +bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx, + struct pt_regs *regs) +{ + if (ctx == RP_CHECK_CHAIN_CALL) + return regs->gpr[1] <= ret->stack; + else + return regs->gpr[1] < ret->stack; +} -- 2.20.1