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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, kbuild test robot <lkp@intel.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>
Subject: [PATCH 4.9 06/44] objtool: Fix function fallthrough detection
Date: Mon, 20 May 2019 14:13:55 +0200	[thread overview]
Message-ID: <20190520115231.784147525@linuxfoundation.org> (raw)
In-Reply-To: <20190520115230.720347034@linuxfoundation.org>

From: Josh Poimboeuf <jpoimboe@redhat.com>

commit e6f393bc939d566ce3def71232d8013de9aaadde upstream.

When a function falls through to the next function due to a compiler
bug, objtool prints some obscure warnings.  For example:

  drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x95: return with modified stack frame
  drivers/regulator/core.o: warning: objtool: regulator_count_voltages()+0x0: stack state mismatch: cfa1=7+32 cfa2=7+8

Instead it should be printing:

  drivers/regulator/core.o: warning: objtool: regulator_supply_is_couple() falls through to next function regulator_count_voltages()

This used to work, but was broken by the following commit:

  13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")

The padding nops at the end of a function aren't actually part of the
function, as defined by the symbol table.  So the 'func' variable in
validate_branch() is getting cleared to NULL when a padding nop is
encountered, breaking the fallthrough detection.

If the current instruction doesn't have a function associated with it,
just consider it to be part of the previously detected function by not
overwriting the previous value of 'func'.

Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Fixes: 13810435b9a7 ("objtool: Support GCC 8's cold subfunctions")
Link: http://lkml.kernel.org/r/546d143820cd08a46624ae8440d093dd6c902cae.1557766718.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 tools/objtool/check.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1779,7 +1779,8 @@ static int validate_branch(struct objtoo
 			return 1;
 		}
 
-		func = insn->func ? insn->func->pfunc : NULL;
+		if (insn->func)
+			func = insn->func->pfunc;
 
 		if (func && insn->ignore) {
 			WARN_FUNC("BUG: why am I validating an ignored function?",



  parent reply	other threads:[~2019-05-20 12:53 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-20 12:13 [PATCH 4.9 00/44] 4.9.178-stable review Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 01/44] net: core: another layer of lists, around PF_MEMALLOC skb handling Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 02/44] locking/rwsem: Prevent decrement of reader count before increment Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 03/44] PCI: hv: Fix a memory leak in hv_eject_device_work() Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 04/44] x86/speculation/mds: Revert CPU buffer clear on double fault exit Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 05/44] x86/speculation/mds: Improve CPU buffer clear documentation Greg Kroah-Hartman
2019-05-20 12:13 ` Greg Kroah-Hartman [this message]
2019-05-20 12:13 ` [PATCH 4.9 07/44] ARM: exynos: Fix a leaked reference by adding missing of_node_put Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 08/44] power: supply: axp288_charger: Fix unchecked return value Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 09/44] arm64: compat: Reduce address limit Greg Kroah-Hartman
2019-05-20 12:13 ` [PATCH 4.9 10/44] arm64: Clear OSDLR_EL1 on CPU boot Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 11/44] sched/x86: Save [ER]FLAGS on context switch Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 12/44] crypto: chacha20poly1305 - set cra_name correctly Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 13/44] crypto: vmx - fix copy-paste error in CTR mode Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 14/44] crypto: crct10dif-generic - fix use via crypto_shash_digest() Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 15/44] crypto: x86/crct10dif-pcl " Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 16/44] ALSA: usb-audio: Fix a memory leak bug Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 17/44] ALSA: hda/hdmi - Read the pin sense from register when repolling Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 18/44] ALSA: hda/hdmi - Consider eld_valid when reporting jack event Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 19/44] ALSA: hda/realtek - EAPD turn on later Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 20/44] ASoC: max98090: Fix restore of DAPM Muxes Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 21/44] ASoC: RT5677-SPI: Disable 16Bit SPI Transfers Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 22/44] mm/mincore.c: make mincore() more conservative Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 23/44] ocfs2: fix ocfs2 read inode data panic in ocfs2_iget Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 24/44] mfd: da9063: Fix OTP control register names to match datasheets for DA9063/63L Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 25/44] mfd: max77620: Fix swapped FPS_PERIOD_MAX_US values Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 26/44] tty/vt: fix write/write race in ioctl(KDSKBSENT) handler Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 27/44] jbd2: check superblock mapped prior to committing Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 28/44] ext4: actually request zeroing of inode table after grow Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 29/44] ext4: fix ext4_show_options for file systems w/o journal Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 30/44] Btrfs: do not start a transaction at iterate_extent_inodes() Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 31/44] bcache: fix a race between cache register and cacheset unregister Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 32/44] bcache: never set KEY_PTRS of journal key to 0 in journal_reclaim() Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 33/44] ipmi:ssif: compare block number correctly for multi-part return messages Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 34/44] crypto: gcm - Fix error return code in crypto_gcm_create_common() Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 35/44] crypto: gcm - fix incompatibility between "gcm" and "gcm_base" Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 36/44] crypto: salsa20 - dont access already-freed walk.iv Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 37/44] crypto: arm/aes-neonbs " Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 38/44] fib_rules: fix error in backport of e9919a24d302 ("fib_rules: return 0...") Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 39/44] writeback: synchronize sync(2) against cgroup writeback membership switches Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 40/44] fs/writeback.c: use rcu_barrier() to wait for inflight wb switches going into workqueue when umount Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 41/44] ext4: zero out the unused memory region in the extent tree block Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 42/44] ext4: fix data corruption caused by overlapping unaligned and aligned IO Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 43/44] ALSA: hda/realtek - Fix for Lenovo B50-70 inverted internal microphone bug Greg Kroah-Hartman
2019-05-20 12:14 ` [PATCH 4.9 44/44] KVM: x86: Skip EFER vs. guest CPUID checks for host-initiated writes Greg Kroah-Hartman
2019-05-20 19:28 ` [PATCH 4.9 00/44] 4.9.178-stable review kernelci.org bot
2019-05-21  8:51 ` Jon Hunter
2019-05-21 10:34 ` Naresh Kamboju
2019-05-21 16:46   ` Greg Kroah-Hartman
2019-05-21 21:39 ` shuah

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