kernel.git/arch/powerpc/kernel/uprobes.c, branch linux-5.13.y

powerpc/uprobes: Validation for prefixed instruction

2021-03-29T01:52:24Z

As per ISA 3.1, prefixed instruction should not cross 64-byte boundary. So don't allow Uprobe on such prefixed instruction. There are two ways probed instruction is changed in mapped pages. First, when Uprobe is activated, it searches for all the relevant pages and replace instruction in them. In this case, if that probe is on the 64-byte unaligned prefixed instruction, error out directly. Second, when Uprobe is already active and user maps a relevant page via mmap(), instruction is replaced via mmap() code path. But because Uprobe is invalid, entire mmap() operation can not be stopped. In this case just print an error and continue. Signed-off-by: Ravi Bangoria Acked-by: Naveen N. Rao Acked-by: Sandipan Das Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210311091538.368590-1-ravi.bangoria@linux.ibm.com

powerpc: fix -Wimplicit-fallthrough

2020-11-18T20:18:09Z

The "fallthrough" pseudo-keyword was added as a portable way to denote intentional fallthrough. Clang will still warn on cases where there is a fallthrough to an immediate break. Add explicit breaks for those cases. Signed-off-by: Nick Desaulniers Tested-by: Nathan Chancellor Reviewed-by: Gustavo A. R. Silva Reviewed-by: Miguel Ojeda Reviewed-by: Nathan Chancellor Acked-by: Michael Ellerman Link: https://github.com/ClangBuiltLinux/linux/issues/236 Signed-off-by: Gustavo A. R. Silva

powerpc: Add ppc_inst_next()

2020-05-26T13:36:51Z

In a few places we want to calculate the address of the next instruction. Previously that was simple, we just added 4 bytes, or if using a u32 * we incremented that pointer by 1. But prefixed instructions make it more complicated, we need to advance by either 4 or 8 bytes depending on the actual instruction. We also can't do pointer arithmetic using struct ppc_inst, because it is always 8 bytes in size on 64-bit, even though we might only need to advance by 4 bytes. So add a ppc_inst_next() helper which calculates the location of the next instruction, if the given instruction was located at the given address. Note the instruction doesn't need to actually be at the address in memory. Although it would seem natural for the value to be passed by value, that makes it too easy to write a loop that will read off the end of a page, eg: for (; src < end; src = ppc_inst_next(src, *src), dest = ppc_inst_next(dest, *dest)) As noticed by Christophe and Jordan, if end is the exact end of a page, and the next page is not mapped, this will fault, because *dest will read 8 bytes, 4 bytes into the next page. So value is passed by reference, so the helper can be careful to use ppc_inst_read() on it. Signed-off-by: Michael Ellerman Reviewed-by: Jordan Niethe Link: https://lore.kernel.org/r/20200522133318.1681406-1-mpe@ellerman.id.au

powerpc: Introduce a function for reporting instruction length

2020-05-18T14:10:38Z

Currently all instructions have the same length, but in preparation for prefixed instructions introduce a function for returning instruction length. Signed-off-by: Jordan Niethe Signed-off-by: Michael Ellerman Reviewed-by: Alistair Popple Link: https://lore.kernel.org/r/20200506034050.24806-18-jniethe5@gmail.com

powerpc: Use a function for reading instructions

2020-05-18T14:10:37Z

Prefixed instructions will mean there are instructions of different length. As a result dereferencing a pointer to an instruction will not necessarily give the desired result. Introduce a function for reading instructions from memory into the instruction data type. Signed-off-by: Jordan Niethe Signed-off-by: Michael Ellerman Reviewed-by: Alistair Popple Link: https://lore.kernel.org/r/20200506034050.24806-13-jniethe5@gmail.com

powerpc: Use a macro for creating instructions from u32s

2020-05-18T14:10:36Z

In preparation for instructions having a more complex data type start using a macro, ppc_inst(), for making an instruction out of a u32. A macro is used so that instructions can be used as initializer elements. Currently this does nothing, but it will allow for creating a data type that can represent prefixed instructions. Signed-off-by: Jordan Niethe [mpe: Change include guard to _ASM_POWERPC_INST_H] Signed-off-by: Michael Ellerman Reviewed-by: Alistair Popple Link: https://lore.kernel.org/r/20200506034050.24806-7-jniethe5@gmail.com

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

2019-05-30T18:26:35Z

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation inc 59 temple place suite 330 boston ma 02111 1307 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 1334 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Richard Fontana Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de Signed-off-by: Greg Kroah-Hartman

powerpc/uprobes: Implement arch_uretprobe_is_alive()

2017-08-24T06:19:21Z

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

uprobes/powerpc: Kill arch_uprobe->ainsn

2013-11-20T15:31:01Z

powerpc has both arch_uprobe->insn and arch_uprobe->ainsn to make the generic code happy. This is no longer needed after the previous change, powerpc can just use "u32 insn". Signed-off-by: Oleg Nesterov Acked-by: Srikar Dronamraju Acked-by: Ananth N Mavinakayanahalli

uretprobes/powerpc: Hijack return address

2013-04-13T13:31:56Z

Hijack the return address and replace it with a trampoline address. PowerPC implementation. Signed-off-by: Anton Arapov Acked-by: Ananth N Mavinakayanahalli Acked-by: Srikar Dronamraju Signed-off-by: Oleg Nesterov