[PATCH 01/17] arm64: entry: mark all entry code as notrace

From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com,
	will@kernel.org, james.morse@arm.com
Cc: mark.rutland@arm.com, keescook@chromium.org, maz@kernel.org,
	broonie@kernel.org, labbott@redhat.com, robin.murphy@arm.com,
	julien.thierry.kdev@gmail.com, alex.popov@linux.com
Subject: [PATCH 01/17] arm64: entry: mark all entry code as notrace
Date: Wed,  8 Jan 2020 18:56:18 +0000	[thread overview]
Message-ID: <20200108185634.1163-2-mark.rutland@arm.com> (raw)
In-Reply-To: <20200108185634.1163-1-mark.rutland@arm.com>

Almost all functions in entry-common.c are marked notrace, with
el1_undef and el1_inv being the only exceptions. We appear to have done
this on the assumption that there were no exception registers that we
needed to snapshot, and thus it was safe to run trace code that might
result in further exceptions and clobber those registers.

However, until we inherit the DAIF flags, our irq flag tracing is stale,
and this discrepancy could set off warnings in some configurations.
Given we don't expect to trigger el1_undef or el1_inv unless something
is already wrong, any irqflag warnigns are liable to mask the
information we'd actually care about.

Let's keep things simple and mark el1_undef and el1_inv as notrace.
Developers can trace do_undefinstr and bad_mode if they really want to
monitor these cases.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Will Deacon <will@kernel.org>
---
 arch/arm64/kernel/entry-common.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c
index 5dce5e56995a..67198142a0fc 100644
--- a/arch/arm64/kernel/entry-common.c
+++ b/arch/arm64/kernel/entry-common.c
@@ -36,14 +36,14 @@ static void notrace el1_pc(struct pt_regs *regs, unsigned long esr)
 }
 NOKPROBE_SYMBOL(el1_pc);
 
-static void el1_undef(struct pt_regs *regs)
+static void notrace el1_undef(struct pt_regs *regs)
 {
 	local_daif_inherit(regs);
 	do_undefinstr(regs);
 }
 NOKPROBE_SYMBOL(el1_undef);
 
-static void el1_inv(struct pt_regs *regs, unsigned long esr)
+static void notrace el1_inv(struct pt_regs *regs, unsigned long esr)
 {
 	local_daif_inherit(regs);
 	bad_mode(regs, 0, esr);
-- 
2.11.0


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