ret_fast_syscall runs when user space makes a syscall. However it needs to be marked as such so the ELF information is correct. Before it was: 101: 8000f300 0 NOTYPE LOCAL DEFAULT 2 ret_fast_syscall But with this change it correctly shows as: 101: 8000f300 96 FUNC LOCAL DEFAULT 2 ret_fast_syscall I see this function when using perf to unwind call stacks from kernel space to user space. Without this change I would need to add some special case logic when using the vmlinux ELF information. Signed-off-by: Drew Richardson <drew.richardson@arm.com> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Conflicts: arch/arm/kernel/head.S
Josh Stone reports: I've discovered a case where both arm and arm64 will miss a ptrace syscall-exit that they should report. If the syscall is entered without TIF_SYSCALL_TRACE set, then it goes on the fast path. It's then possible to have TIF_SYSCALL_TRACE added in the middle of the syscall, but ret_fast_syscall doesn't check this flag again. Fix this by always checking for a syscall trace in the fast exit path. Reported-by: Josh Stone <jistone@redhat.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
BSYM() was invented to allow us to work around a problem with the assembler, where local symbols resolved by the assembler for the 'adr' instruction did not take account of their ISA. Since we don't want BSYM() used elsewhere, replace BSYM() with a new macro 'badr', which is like the 'adr' pseudo-op, but with the BSYM() mechanics integrated into it. This ensures that the BSYM()-ification is only used in conjunction with 'adr'. Acked-by: Dave Martin <Dave.Martin@arm.com> Acked-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
The ftrace assembly code doesn't need to live in entry-common.S and be surrounded with #ifdef CONFIG_FUNCTION_TRACER. Instead, move it to its own file and conditionally assemble it. Tested-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
If we are not changing the control register value, avoid writing to it. Writes to the control register can be very expensive, taking around a hundred cycles or so. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
ARMv6 and greater introduced a new instruction ("bx") which can be used
to return from function calls. Recent CPUs perform better when the
"bx lr" instruction is used rather than the "mov pc, lr" instruction,
and this sequence is strongly recommended to be used by the ARM
architecture manual (section A.4.1.1).
We provide a new macro "ret" with all its variants for the condition
code which will resolve to the appropriate instruction.
Rather than doing this piecemeal, and miss some instances, change all
the "mov pc" instances to use the new macro, with the exception of
the "movs" instruction and the kprobes code. This allows us to detect
the "mov pc, lr" case and fix it up - and also gives us the possibility
of deploying this for other registers depending on the CPU selection.
Reported-by: Will Deacon <will.deacon@arm.com>
Tested-by: Stephen Warren <swarren@nvidia.com> # Tegra Jetson TK1
Tested-by: Robert Jarzmik <robert.jarzmik@free.fr> # mioa701_bootresume.S
Tested-by: Andrew Lunn <andrew@lunn.ch> # Kirkwood
Tested-by: Shawn Guo <shawn.guo@freescale.com>
Tested-by: Tony Lindgren <tony@atomide.com> # OMAPs
Tested-by: Gregory CLEMENT <gregory.clement@free-electrons.com> # Armada XP, 375, 385
Acked-by: Sekhar Nori <nsekhar@ti.com> # DaVinci
Acked-by: Christoffer Dall <christoffer.dall@linaro.org> # kvm/hyp
Acked-by: Haojian Zhuang <haojian.zhuang@gmail.com> # PXA3xx
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> # Xen
Tested-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> # ARMv7M
Tested-by: Simon Horman <horms+renesas@verge.net.au> # Shmobile
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
We can use the alignment_trap assembly macro here too. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Add ARM_BE8() helper to wrap any code conditional on being compile when CONFIG_ARM_ENDIAN_BE8 is selected and convert existing places where this is to use it. Acked-by: Nicolas Pitre <nico@linaro.org> Reviewed-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Commit 377747c40657 ("ARM: entry: allow ARM-private syscalls to be
restarted") reworked the low-level syscall dispatcher to allow
restarting of ARM-private syscalls. Unfortunately, this relocated the
label used to dispatch a private syscall from the trace path, so that
the invocation would be bypassed altogether!
This causes applications to fail under strace as soon as they rely on
a private syscall (e.g. set_tls):
set_tls(0xb6fad4c0, 0xb6fadb98, 0xb6fb1050, 0xb6fad4c0, 0xb6fb1050)
= -1 ENOSYS (Function not implemented)
This patch fixes the label so that we correctly dispatch private
syscalls from the trace path.
Reported-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Tested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>