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GET /api/patches/775850/?format=api
HTTP 200 OK
Allow: GET, PUT, PATCH, HEAD, OPTIONS
Content-Type: application/json
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{
    "id": 775850,
    "url": "http://patchwork.ozlabs.org/api/patches/775850/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20170614154400.17377-1-naveen.n.rao@linux.vnet.ibm.com/",
    "project": {
        "id": 2,
        "url": "http://patchwork.ozlabs.org/api/projects/2/?format=api",
        "name": "Linux PPC development",
        "link_name": "linuxppc-dev",
        "list_id": "linuxppc-dev.lists.ozlabs.org",
        "list_email": "linuxppc-dev@lists.ozlabs.org",
        "web_url": "https://github.com/linuxppc/wiki/wiki",
        "scm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git",
        "webscm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/",
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        "commit_url_format": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id={}"
    },
    "msgid": "<20170614154400.17377-1-naveen.n.rao@linux.vnet.ibm.com>",
    "list_archive_url": "https://lore.kernel.org/linuxppc-dev/20170614154400.17377-1-naveen.n.rao@linux.vnet.ibm.com/",
    "date": "2017-06-14T15:44:00",
    "name": "powerpc/uprobes: Implement arch_uretprobe_is_alive()",
    "commit_ref": "2dea1d9c38e481051fa0e62807e518c5768e62dd",
    "pull_url": null,
    "state": "accepted",
    "archived": false,
    "hash": "30474e2b644a0c8138eadaee17db030ac35d8544",
    "submitter": {
        "id": 15185,
        "url": "http://patchwork.ozlabs.org/api/people/15185/?format=api",
        "name": "Naveen N. Rao",
        "email": "naveen.n.rao@linux.vnet.ibm.com"
    },
    "delegate": null,
    "mbox": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20170614154400.17377-1-naveen.n.rao@linux.vnet.ibm.com/mbox/",
    "series": [],
    "comments": "http://patchwork.ozlabs.org/api/patches/775850/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/775850/checks/",
    "tags": {},
    "related": [],
    "headers": {
        "Return-Path": "<linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org>",
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            "from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139])\n\tby d23relay09.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id\n\tv5EFiKVa3801454\n\tfor <linuxppc-dev@lists.ozlabs.org>; Thu, 15 Jun 2017 01:44:20 +1000",
            "from d23av04.au.ibm.com (localhost [127.0.0.1])\n\tby d23av04.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id\n\tv5EFiHMX017204\n\tfor <linuxppc-dev@lists.ozlabs.org>; Thu, 15 Jun 2017 01:44:18 +1000",
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        ],
        "From": "\"Naveen N. Rao\" <naveen.n.rao@linux.vnet.ibm.com>",
        "To": "Michael Ellerman <mpe@ellerman.id.au>",
        "Subject": "[PATCH] powerpc/uprobes: Implement arch_uretprobe_is_alive()",
        "Date": "Wed, 14 Jun 2017 21:14:00 +0530",
        "X-Mailer": "git-send-email 2.12.2",
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        "x-cbid": "17061415-1617-0000-0000-000001E59807",
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        "x-cbparentid": "17061415-1618-0000-0000-0000482BFF84",
        "Message-Id": "<20170614154400.17377-1-naveen.n.rao@linux.vnet.ibm.com>",
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        "Precedence": "list",
        "List-Id": "Linux on PowerPC Developers Mail List\n\t<linuxppc-dev.lists.ozlabs.org>",
        "List-Unsubscribe": "<https://lists.ozlabs.org/options/linuxppc-dev>,\n\t<mailto:linuxppc-dev-request@lists.ozlabs.org?subject=unsubscribe>",
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        "List-Subscribe": "<https://lists.ozlabs.org/listinfo/linuxppc-dev>,\n\t<mailto:linuxppc-dev-request@lists.ozlabs.org?subject=subscribe>",
        "Cc": "linuxppc-dev@lists.ozlabs.org,\n\tSrikar Dronamraju <srikar@linux.vnet.ibm.com>, zsun@redhat.com,\n\tGustavo Luiz Duarte <gduarte@redhat.com>",
        "Errors-To": "linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org",
        "Sender": "\"Linuxppc-dev\"\n\t<linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org>"
    },
    "content": "This helper is used to detect if a uprobe'd function has returned\nthrough a setjmp/longjmp, rather than branching to the LR that was\nupdated previously by us. This fixes a SIGSEGV that gets generated when\nprograms use setjmp/longjmp with uretprobes.\n\nWe use the arm64 model (arch/arm64/kernel/probes/uprobes.c:\narch_uretprobe_is_alive()) for detecting when stack frames have been\nremoved from under us.\n\nReference:\nhttps://marc.info/?l=linux-kernel&m=143748610330073\ncommit 7b868e4802a86 (\"uprobes/x86: Reimplement arch_uretprobe_is_alive()\")\ncommit db087ef69a2b1 (\"uprobes/x86: Make arch_uretprobe_is_alive(RP_CHECK_CALL) more\nclever\")\n\nTested with the test program from:\nhttps://sourceware.org/git/gitweb.cgi?p=systemtap.git;a=blob;f=testsuite/systemtap.base/bz5274.c;hb=HEAD\n\nAnd this script:\n    $ cat test.sh\n    #!/bin/bash\n\n    perf probe -x ./bz5274 -a bz5274_main_return=main%return\n    perf probe -x ./bz5274 -a bz5274_funca_return=funca%return\n    perf probe -x ./bz5274 -a bz5274_funcb_return=funcb%return\n    perf probe -x ./bz5274 -a bz5274_funcc_return=funcc%return\n    perf probe -x ./bz5274 -a bz5274_funcd_return=funcd%return\n\n    perf record -e 'probe_bz5274:*' -aR ./bz5274\n\nReported-by: Gustavo Luiz Duarte <gduarte@redhat.com>\nReported-by: zsun@redhat.com\nSigned-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>\n---\n arch/powerpc/kernel/uprobes.c | 9 +++++++++\n 1 file changed, 9 insertions(+)",
    "diff": "diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c\nindex 003b20964ea0..5d105b8eeece 100644\n--- a/arch/powerpc/kernel/uprobes.c\n+++ b/arch/powerpc/kernel/uprobes.c\n@@ -205,3 +205,12 @@ arch_uretprobe_hijack_return_addr(unsigned long trampoline_vaddr, struct pt_regs\n \n \treturn orig_ret_vaddr;\n }\n+\n+bool arch_uretprobe_is_alive(struct return_instance *ret, enum rp_check ctx,\n+\t\t\t\tstruct pt_regs *regs)\n+{\n+\tif (ctx == RP_CHECK_CHAIN_CALL)\n+\t\treturn regs->gpr[1] <= ret->stack;\n+\telse\n+\t\treturn regs->gpr[1] < ret->stack;\n+}\n",
    "prefixes": []
}