Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933432AbbKMAEd (ORCPT ); Thu, 12 Nov 2015 19:04:33 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:45006 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932254AbbKLXS7 (ORCPT ); Thu, 12 Nov 2015 18:18:59 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Li Bin , Catalin Marinas , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 032/155] arm64: ftrace: fix function_graph tracer panic Date: Thu, 12 Nov 2015 15:16:26 -0800 Message-Id: <1447370309-357-33-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1447370309-357-1-git-send-email-kamal@canonical.com> References: <1447370309-357-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4671 Lines: 120 3.19.8-ckt10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Li Bin commit ee556d00cf20012e889344a0adbbf809ab5015a3 upstream. When function graph tracer is enabled, the following operation will trigger panic: mount -t debugfs nodev /sys/kernel echo next_tgid > /sys/kernel/tracing/set_ftrace_filter echo function_graph > /sys/kernel/tracing/current_tracer ls /proc/ ------------[ cut here ]------------ [ 198.501417] Unable to handle kernel paging request at virtual address cb88537fdc8ba316 [ 198.506126] pgd = ffffffc008f79000 [ 198.509363] [cb88537fdc8ba316] *pgd=00000000488c6003, *pud=00000000488c6003, *pmd=0000000000000000 [ 198.517726] Internal error: Oops: 94000005 [#1] SMP [ 198.518798] Modules linked in: [ 198.520582] CPU: 1 PID: 1388 Comm: ls Tainted: G [ 198.521800] Hardware name: linux,dummy-virt (DT) [ 198.522852] task: ffffffc0fa9e8000 ti: ffffffc0f9ab0000 task.ti: ffffffc0f9ab0000 [ 198.524306] PC is at next_tgid+0x30/0x100 [ 198.525205] LR is at return_to_handler+0x0/0x20 [ 198.526090] pc : [] lr : [] pstate: 60000145 [ 198.527392] sp : ffffffc0f9ab3d40 [ 198.528084] x29: ffffffc0f9ab3d40 x28: ffffffc0f9ab0000 [ 198.529406] x27: ffffffc000d6a000 x26: ffffffc000b786e8 [ 198.530659] x25: ffffffc0002a1900 x24: ffffffc0faf16c00 [ 198.531942] x23: ffffffc0f9ab3ea0 x22: 0000000000000002 [ 198.533202] x21: ffffffc000d85050 x20: 0000000000000002 [ 198.534446] x19: 0000000000000002 x18: 0000000000000000 [ 198.535719] x17: 000000000049fa08 x16: ffffffc000242efc [ 198.537030] x15: 0000007fa472b54c x14: ffffffffff000000 [ 198.538347] x13: ffffffc0fada84a0 x12: 0000000000000001 [ 198.539634] x11: ffffffc0f9ab3d70 x10: ffffffc0f9ab3d70 [ 198.540915] x9 : ffffffc0000907c0 x8 : ffffffc0f9ab3d40 [ 198.542215] x7 : 0000002e330f08f0 x6 : 0000000000000015 [ 198.543508] x5 : 0000000000000f08 x4 : ffffffc0f9835ec0 [ 198.544792] x3 : cb88537fdc8ba316 x2 : cb88537fdc8ba306 [ 198.546108] x1 : 0000000000000002 x0 : ffffffc000d85050 [ 198.547432] [ 198.547920] Process ls (pid: 1388, stack limit = 0xffffffc0f9ab0020) [ 198.549170] Stack: (0xffffffc0f9ab3d40 to 0xffffffc0f9ab4000) [ 198.582568] Call trace: [ 198.583313] [] next_tgid+0x30/0x100 [ 198.584359] [] ftrace_graph_caller+0x6c/0x70 [ 198.585503] [] ftrace_graph_caller+0x6c/0x70 [ 198.586574] [] ftrace_graph_caller+0x6c/0x70 [ 198.587660] [] ftrace_graph_caller+0x6c/0x70 [ 198.588896] Code: aa0003f5 2a0103f4 b4000102 91004043 (885f7c60) [ 198.591092] ---[ end trace 6a346f8f20949ac8 ]--- This is because when using function graph tracer, if the traced function return value is in multi regs ([x0-x7]), return_to_handler may corrupt them. So in return_to_handler, the parameter regs should be protected properly. Signed-off-by: Li Bin Acked-by: AKASHI Takahiro Signed-off-by: Catalin Marinas Signed-off-by: Kamal Mostafa --- arch/arm64/kernel/entry-ftrace.S | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S index 08cafc5..0f03a8f 100644 --- a/arch/arm64/kernel/entry-ftrace.S +++ b/arch/arm64/kernel/entry-ftrace.S @@ -178,6 +178,24 @@ ENTRY(ftrace_stub) ENDPROC(ftrace_stub) #ifdef CONFIG_FUNCTION_GRAPH_TRACER + /* save return value regs*/ + .macro save_return_regs + sub sp, sp, #64 + stp x0, x1, [sp] + stp x2, x3, [sp, #16] + stp x4, x5, [sp, #32] + stp x6, x7, [sp, #48] + .endm + + /* restore return value regs*/ + .macro restore_return_regs + ldp x0, x1, [sp] + ldp x2, x3, [sp, #16] + ldp x4, x5, [sp, #32] + ldp x6, x7, [sp, #48] + add sp, sp, #64 + .endm + /* * void ftrace_graph_caller(void) * @@ -204,11 +222,11 @@ ENDPROC(ftrace_graph_caller) * only when CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST is enabled. */ ENTRY(return_to_handler) - str x0, [sp, #-16]! + save_return_regs mov x0, x29 // parent's fp bl ftrace_return_to_handler// addr = ftrace_return_to_hander(fp); mov x30, x0 // restore the original return address - ldr x0, [sp], #16 + restore_return_regs ret END(return_to_handler) #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/