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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, "Steven Rostedt (VMware)" <rostedt@goodmis.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.19 67/73] x86/ftrace: Do not call function graph from dynamic trampolines
Date: Fri,  7 Jun 2019 17:39:54 +0200	[thread overview]
Message-ID: <20190607153856.353446303@linuxfoundation.org> (raw)
In-Reply-To: <20190607153848.669070800@linuxfoundation.org>

[ Upstream commit d2a68c4effd821f0871d20368f76b609349c8a3b ]

Since commit 79922b8009c07 ("ftrace: Optimize function graph to be
called directly"), dynamic trampolines should not be calling the
function graph tracer at the end. If they do, it could cause the function
graph tracer to trace functions that it filtered out.

Right now it does not cause a problem because there's a test to check if
the function graph tracer is attached to the same function as the
function tracer, which for now is true. But the function graph tracer is
undergoing changes that can make this no longer true which will cause
the function graph tracer to trace other functions.

 For example:

 # cd /sys/kernel/tracing/
 # echo do_IRQ > set_ftrace_filter
 # mkdir instances/foo
 # echo ip_rcv > instances/foo/set_ftrace_filter
 # echo function_graph > current_tracer
 # echo function > instances/foo/current_tracer

Would cause the function graph tracer to trace both do_IRQ and ip_rcv,
if the current tests change.

As the current tests prevent this from being a problem, this code does
not need to be backported. But it does make the code cleaner.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kernel/ftrace.c    | 41 ++++++++++++++++++++-----------------
 arch/x86/kernel/ftrace_64.S |  8 ++++----
 2 files changed, 26 insertions(+), 23 deletions(-)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 4d2a401c178b..38c798b1dbd2 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -752,18 +752,20 @@ union ftrace_op_code_union {
 	} __attribute__((packed));
 };
 
+#define RET_SIZE		1
+
 static unsigned long
 create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
 {
-	unsigned const char *jmp;
 	unsigned long start_offset;
 	unsigned long end_offset;
 	unsigned long op_offset;
 	unsigned long offset;
 	unsigned long size;
-	unsigned long ip;
+	unsigned long retq;
 	unsigned long *ptr;
 	void *trampoline;
+	void *ip;
 	/* 48 8b 15 <offset> is movq <offset>(%rip), %rdx */
 	unsigned const char op_ref[] = { 0x48, 0x8b, 0x15 };
 	union ftrace_op_code_union op_ptr;
@@ -783,27 +785,27 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
 
 	/*
 	 * Allocate enough size to store the ftrace_caller code,
-	 * the jmp to ftrace_epilogue, as well as the address of
-	 * the ftrace_ops this trampoline is used for.
+	 * the iret , as well as the address of the ftrace_ops this
+	 * trampoline is used for.
 	 */
-	trampoline = alloc_tramp(size + MCOUNT_INSN_SIZE + sizeof(void *));
+	trampoline = alloc_tramp(size + RET_SIZE + sizeof(void *));
 	if (!trampoline)
 		return 0;
 
-	*tramp_size = size + MCOUNT_INSN_SIZE + sizeof(void *);
+	*tramp_size = size + RET_SIZE + sizeof(void *);
 
 	/* Copy ftrace_caller onto the trampoline memory */
 	ret = probe_kernel_read(trampoline, (void *)start_offset, size);
-	if (WARN_ON(ret < 0)) {
-		tramp_free(trampoline, *tramp_size);
-		return 0;
-	}
+	if (WARN_ON(ret < 0))
+		goto fail;
 
-	ip = (unsigned long)trampoline + size;
+	ip = trampoline + size;
 
-	/* The trampoline ends with a jmp to ftrace_epilogue */
-	jmp = ftrace_jmp_replace(ip, (unsigned long)ftrace_epilogue);
-	memcpy(trampoline + size, jmp, MCOUNT_INSN_SIZE);
+	/* The trampoline ends with ret(q) */
+	retq = (unsigned long)ftrace_stub;
+	ret = probe_kernel_read(ip, (void *)retq, RET_SIZE);
+	if (WARN_ON(ret < 0))
+		goto fail;
 
 	/*
 	 * The address of the ftrace_ops that is used for this trampoline
@@ -813,17 +815,15 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
 	 * the global function_trace_op variable.
 	 */
 
-	ptr = (unsigned long *)(trampoline + size + MCOUNT_INSN_SIZE);
+	ptr = (unsigned long *)(trampoline + size + RET_SIZE);
 	*ptr = (unsigned long)ops;
 
 	op_offset -= start_offset;
 	memcpy(&op_ptr, trampoline + op_offset, OP_REF_SIZE);
 
 	/* Are we pointing to the reference? */
-	if (WARN_ON(memcmp(op_ptr.op, op_ref, 3) != 0)) {
-		tramp_free(trampoline, *tramp_size);
-		return 0;
-	}
+	if (WARN_ON(memcmp(op_ptr.op, op_ref, 3) != 0))
+		goto fail;
 
 	/* Load the contents of ptr into the callback parameter */
 	offset = (unsigned long)ptr;
@@ -838,6 +838,9 @@ create_trampoline(struct ftrace_ops *ops, unsigned int *tramp_size)
 	ops->flags |= FTRACE_OPS_FL_ALLOC_TRAMP;
 
 	return (unsigned long)trampoline;
+fail:
+	tramp_free(trampoline, *tramp_size);
+	return 0;
 }
 
 static unsigned long calc_trampoline_call_offset(bool save_regs)
diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index 91b2cff4b79a..75f2b36b41a6 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -171,9 +171,6 @@ GLOBAL(ftrace_call)
 	restore_mcount_regs
 
 	/*
-	 * The copied trampoline must call ftrace_epilogue as it
-	 * still may need to call the function graph tracer.
-	 *
 	 * The code up to this label is copied into trampolines so
 	 * think twice before adding any new code or changing the
 	 * layout here.
@@ -185,7 +182,10 @@ GLOBAL(ftrace_graph_call)
 	jmp ftrace_stub
 #endif
 
-/* This is weak to keep gas from relaxing the jumps */
+/*
+ * This is weak to keep gas from relaxing the jumps.
+ * It is also used to copy the retq for trampolines.
+ */
 WEAK(ftrace_stub)
 	retq
 ENDPROC(ftrace_caller)
-- 
2.20.1




  parent reply	other threads:[~2019-06-07 15:46 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-07 15:38 [PATCH 4.19 00/73] 4.19.49-stable review Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 01/73] sparc64: Fix regression in non-hypervisor TLB flush xcall Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 02/73] include/linux/bitops.h: sanitize rotate primitives Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 03/73] xhci: update bounce buffer with correct sg num Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 04/73] xhci: Use %zu for printing size_t type Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 05/73] xhci: Convert xhci_handshake() to use readl_poll_timeout_atomic() Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 06/73] usb: xhci: avoid null pointer deref when bos field is NULL Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 07/73] usbip: usbip_host: fix BUG: sleeping function called from invalid context Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 08/73] usbip: usbip_host: fix stub_dev lock context imbalance regression Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 09/73] USB: Fix slab-out-of-bounds write in usb_get_bos_descriptor Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 10/73] USB: sisusbvga: fix oops in error path of sisusb_probe Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 11/73] USB: Add LPM quirk for Surface Dock GigE adapter Greg Kroah-Hartman
2019-06-07 15:38 ` [PATCH 4.19 12/73] USB: rio500: refuse more than one device at a time Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 13/73] USB: rio500: fix memory leak in close after disconnect Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 14/73] media: usb: siano: Fix general protection fault in smsusb Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 15/73] media: usb: siano: Fix false-positive "uninitialized variable" warning Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 16/73] media: smsusb: better handle optional alignment Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 17/73] brcmfmac: fix NULL pointer derefence during USB disconnect Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 18/73] scsi: zfcp: fix missing zfcp_port reference put on -EBUSY from port_remove Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 19/73] scsi: zfcp: fix to prevent port_remove with pure auto scan LUNs (only sdevs) Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 20/73] tracing: Avoid memory leak in predicate_parse() Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 21/73] Btrfs: fix wrong ctime and mtime of a directory after log replay Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 22/73] Btrfs: fix race updating log root item during fsync Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 23/73] Btrfs: fix fsync not persisting changed attributes of a directory Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 24/73] Btrfs: incremental send, fix file corruption when no-holes feature is enabled Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 25/73] iio: dac: ds4422/ds4424 fix chip verification Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 26/73] iio: adc: ti-ads8688: fix timestamp is not updated in buffer Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 27/73] s390/crypto: fix gcm-aes-s390 selftest failures Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 28/73] s390/crypto: fix possible sleep during spinlock aquired Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 29/73] KVM: PPC: Book3S HV: XIVE: Do not clear IRQ data of passthrough interrupts Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 30/73] powerpc/perf: Fix MMCRA corruption by bhrb_filter Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 31/73] ALSA: line6: Assure canceling delayed work at disconnection Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 32/73] ALSA: hda/realtek - Set default power save node to 0 Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 33/73] ALSA: hda/realtek - Improve the headset mic for Acer Aspire laptops Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 34/73] KVM: s390: Do not report unusabled IDs via KVM_CAP_MAX_VCPU_ID Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 35/73] drm/nouveau/i2c: Disable i2c bus access after ->fini() Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 36/73] i2c: mlxcpld: Fix wrong initialization order in probe Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 37/73] i2c: synquacer: fix synquacer_i2c_doxfer() return value Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 38/73] tty: serial: msm_serial: Fix XON/XOFF Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 39/73] tty: max310x: Fix external crystal register setup Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 40/73] memcg: make it work on sparse non-0-node systems Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 41/73] kernel/signal.c: trace_signal_deliver when signal_group_exit Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 42/73] arm64: Fix the arm64_personality() syscall wrapper redirection Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 43/73] docs: Fix conf.py for Sphinx 2.0 Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 44/73] doc: Cope with the deprecation of AutoReporter Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 45/73] doc: Cope with Sphinx logging deprecations Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 46/73] ima: show rules with IMA_INMASK correctly Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 47/73] evm: check hash algorithm passed to init_desc() Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 48/73] vt/fbcon: deinitialize resources in visual_init() after failed memory allocation Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 49/73] serial: sh-sci: disable DMA for uart_console Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 50/73] staging: vc04_services: prevent integer overflow in create_pagelist() Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 51/73] staging: wlan-ng: fix adapter initialization failure Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 52/73] cifs: fix memory leak of pneg_inbuf on -EOPNOTSUPP ioctl case Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 53/73] CIFS: cifs_read_allocate_pages: dont iterate through whole page array on ENOMEM Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 54/73] Revert "lockd: Show pid of lockd for remote locks" Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 55/73] gcc-plugins: Fix build failures under Darwin host Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 56/73] drm/tegra: gem: Fix CPU-cache maintenance for BOs allocated using get_pages() Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 57/73] drm/vmwgfx: Dont send drm sysfs hotplug events on initial master set Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 58/73] drm/sun4i: Fix sun8i HDMI PHY clock initialization Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 59/73] drm/sun4i: Fix sun8i HDMI PHY configuration for > 148.5 MHz Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 60/73] drm/rockchip: shutdown drm subsystem on shutdown Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 61/73] drm/lease: Make sure implicit planes are leased Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 62/73] Compiler Attributes: add support for __copy (gcc >= 9) Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 63/73] include/linux/module.h: copy __init/__exit attrs to init/cleanup_module Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 64/73] Revert "x86/build: Move _etext to actual end of .text" Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 65/73] Revert "binder: fix handling of misaligned binder object" Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 66/73] binder: fix race between munmap() and direct reclaim Greg Kroah-Hartman
2019-06-07 15:39 ` Greg Kroah-Hartman [this message]
2019-06-07 15:39 ` [PATCH 4.19 68/73] x86/ftrace: Set trampoline pages as executable Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 69/73] x86/kprobes: Set instruction page " Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 70/73] scsi: lpfc: Fix backport of faf5a744f4f8 ("scsi: lpfc: avoid uninitialized variable warning") Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 71/73] of: overlay: validate overlay properties #address-cells and #size-cells Greg Kroah-Hartman
2019-06-07 15:39 ` [PATCH 4.19 72/73] of: overlay: set node fields from properties when add new overlay node Greg Kroah-Hartman
2019-06-07 15:40 ` [PATCH 4.19 73/73] media: uvcvideo: Fix uvc_alloc_entity() allocation alignment Greg Kroah-Hartman
2019-06-07 19:29 ` [PATCH 4.19 00/73] 4.19.49-stable review kernelci.org bot
2019-06-08  7:53 ` Naresh Kamboju
2019-06-08 18:49 ` Guenter Roeck

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