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From 93cd670426aaf4951bceb8f24f0ce63c24e16f5d Mon Sep 17 00:00:00 2001
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From: Tao Liu <ltao@redhat.com>
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Date: Wed, 16 Nov 2022 20:09:22 +0800
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Subject: [PATCH 19/28] x86_64: Correct the identifier when locating the call
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instruction
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The previous implementation to locate the call instruction is
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to strstr "call", then check whether the previous char is ' '
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or '\t'. The implementation is problematic. For example it
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cannot resolve the following disassembly string:
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"0xffffffffc0995378 <nfs41_callback_svc+344>:\tcall 0xffffffff8ecfa4c0 <schedule>\n"
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strstr will locate the "_call" and char check fails,
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as a result, extract_hex fails to get the calling address.
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NOTE: the issue is more likely to be reproduced when patch[1] applied.
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Because without patch[1], the disassembly string will be as follows,
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so the issue is no longer reproducible.
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"0xffffffffc0995378:\tcall 0xffffffff8ecfa4c0 <schedule>\n"
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Before the patch:
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crash> bt 1472
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PID: 1472 TASK: ffff8c121fa72f70 CPU: 18 COMMAND: "nfsv4.1-svc"
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#0 [ffff8c16231a3db8] __schedule at ffffffff8ecf9ef3
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#1 [ffff8c16231a3e40] schedule at ffffffff8ecfa4e9
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After the patch:
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crash> bt 1472
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PID: 1472 TASK: ffff8c121fa72f70 CPU: 18 COMMAND: "nfsv4.1-svc"
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#0 [ffff8c16231a3db8] __schedule at ffffffff8ecf9ef3
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#1 [ffff8c16231a3e40] schedule at ffffffff8ecfa4e9
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#2 [ffff8c16231a3e50] nfs41_callback_svc at ffffffffc099537d [nfsv4]
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#3 [ffff8c16231a3ec8] kthread at ffffffff8e6b966f
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#4 [ffff8c16231a3f50] ret_from_fork at ffffffff8ed07898
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This patch fix the issue by strstr "\tcall" and " call", to
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locate the correct call instruction.
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[1]: https://listman.redhat.com/archives/crash-utility/2022-August/010085.html
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Signed-off-by: Tao Liu <ltao@redhat.com>
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Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
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---
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x86_64.c | 3 +--
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1 file changed, 1 insertion(+), 2 deletions(-)
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diff --git a/x86_64.c b/x86_64.c
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index b2a536e4b19c..292c240e887e 100644
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--- a/x86_64.c
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+++ b/x86_64.c
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@@ -4429,8 +4429,7 @@ x86_64_function_called_by(ulong rip)
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if (gdb_pass_through(buf, pc->tmpfile2, GNU_RETURN_ON_ERROR)) {
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rewind(pc->tmpfile2);
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while (fgets(buf, BUFSIZE, pc->tmpfile2)) {
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- if ((p1 = strstr(buf, "callq")) &&
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- whitespace(*(p1-1))) {
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+ if ((p1 = strstr(buf, " callq")) || (p1 = strstr(buf, "\tcallq"))) {
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if (extract_hex(p1, &value, NULLCHAR, TRUE))
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break;
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}
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--
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2.37.1
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