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2020-03-05MIPS: VPE: Fix a double free and a memory leak in 'release_vpe()'Christophe JAILLET1-1/+1
commit bef8e2dfceed6daeb6ca3e8d33f9c9d43b926580 upstream. Pointer on the memory allocated by 'alloc_progmem()' is stored in 'v->load_addr'. So this is this memory that should be freed by 'release_progmem()'. 'release_progmem()' is only a call to 'kfree()'. With the current code, there is both a double free and a memory leak. Fix it by passing the correct pointer to 'release_progmem()'. Fixes: e01402b115ccc ("More AP / SP bits for the 34K, the Malta bits and things. Still wants") Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Signed-off-by: Paul Burton <paulburton@kernel.org> Cc: ralf@linux-mips.org Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: kernel-janitors@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-27mips: avoid explicit UB in assignment of mips_io_port_baseNick Desaulniers1-1/+1
[ Upstream commit 12051b318bc3ce5b42d6d786191008284b067d83 ] The code in question is modifying a variable declared const through pointer manipulation. Such code is explicitly undefined behavior, and is the lone issue preventing malta_defconfig from booting when built with Clang: If an attempt is made to modify an object defined with a const-qualified type through use of an lvalue with non-const-qualified type, the behavior is undefined. LLVM is removing such assignments. A simple fix is to not declare variables const that you plan on modifying. Limiting the scope would be a better method of preventing unwanted writes to such a variable. Further, the code in question mentions "compiler bugs" without any links to bug reports, so it is difficult to know if the issue is resolved in GCC. The patch was authored in 2006, which would have been GCC 4.0.3 or 4.1.1. The minimal supported version of GCC in the Linux kernel is currently 4.6. For what its worth, there was UB before the commit in question, it just added a barrier and got lucky IRT codegen. I don't think there's any actual compiler bugs related, just runtime bugs due to UB. Link: https://github.com/ClangBuiltLinux/linux/issues/610 Fixes: 966f4406d903 ("[MIPS] Work around bad code generation for <asm/io.h>.") Reported-by: Nathan Chancellor <natechancellor@gmail.com> Debugged-by: Nathan Chancellor <natechancellor@gmail.com> Suggested-by: Eli Friedman <efriedma@quicinc.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Tested-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: ralf@linux-mips.org Cc: jhogan@kernel.org Cc: Maciej W. Rozycki <macro@linux-mips.org> Cc: Hassan Naveed <hnaveed@wavecomp.com> Cc: Stephen Kitt <steve@sk2.org> Cc: Serge Semin <fancer.lancer@gmail.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: clang-built-linux@googlegroups.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-01-17mips: cacheinfo: report shared CPU mapVladimir Kondratiev1-1/+26
[ Upstream commit 3b1313eb32c499d46dc4c3e896d19d9564c879c4 ] Report L1 caches as shared per core; L2 - per cluster. This fixes "perf" that went crazy if shared_cpu_map attribute not reported on sysfs, in form of /sys/devices/system/cpu/cpu*/cache/index*/shared_cpu_list /sys/devices/system/cpu/cpu*/cache/index*/shared_cpu_map Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@intel.com> Signed-off-by: Paul Burton <paulburton@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-11-10MIPS: bmips: mark exception vectors as char arraysJonas Gorski1-4/+4
[ Upstream commit e4f5cb1a9b27c0f94ef4f5a0178a3fde2d3d0e9e ] The vectors span more than one byte, so mark them as arrays. Fixes the following build error when building when using GCC 8.3: In file included from ./include/linux/string.h:19, from ./include/linux/bitmap.h:9, from ./include/linux/cpumask.h:12, from ./arch/mips/include/asm/processor.h:15, from ./arch/mips/include/asm/thread_info.h:16, from ./include/linux/thread_info.h:38, from ./include/asm-generic/preempt.h:5, from ./arch/mips/include/generated/asm/preempt.h:1, from ./include/linux/preempt.h:81, from ./include/linux/spinlock.h:51, from ./include/linux/mmzone.h:8, from ./include/linux/bootmem.h:8, from arch/mips/bcm63xx/prom.c:10: arch/mips/bcm63xx/prom.c: In function 'prom_init': ./arch/mips/include/asm/string.h:162:11: error: '__builtin_memcpy' forming offset [2, 32] is out of the bounds [0, 1] of object 'bmips_smp_movevec' with type 'char' [-Werror=array-bounds] __ret = __builtin_memcpy((dst), (src), __len); \ ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/mips/bcm63xx/prom.c:97:3: note: in expansion of macro 'memcpy' memcpy((void *)0xa0000200, &bmips_smp_movevec, 0x20); ^~~~~~ In file included from arch/mips/bcm63xx/prom.c:14: ./arch/mips/include/asm/bmips.h:80:13: note: 'bmips_smp_movevec' declared here extern char bmips_smp_movevec; Fixes: 18a1eef92dcd ("MIPS: BMIPS: Introduce bmips.h") Signed-off-by: Jonas Gorski <jonas.gorski@gmail.com> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Paul Burton <paulburton@kernel.org> Cc: linux-mips@vger.kernel.org Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-10-17MIPS: elf_hwcap: Export userspace ASEsJiaxun Yang1-0/+33
commit 38dffe1e4dde1d3174fdce09d67370412843ebb5 upstream. A Golang developer reported MIPS hwcap isn't reflecting instructions that the processor actually supported so programs can't apply optimized code at runtime. Thus we export the ASEs that can be used in userspace programs. Reported-by: Meng Zhuo <mengzhuo1203@gmail.com> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com> Cc: linux-mips@vger.kernel.org Cc: Paul Burton <paul.burton@mips.com> Cc: <stable@vger.kernel.org> # 4.14+ Signed-off-by: Paul Burton <paul.burton@mips.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-11MIPS: Treat Loongson Extensions as ASEsJiaxun Yang2-0/+10
commit d2f965549006acb865c4638f1f030ebcefdc71f6 upstream. Recently, binutils had split Loongson-3 Extensions into four ASEs: MMI, CAM, EXT, EXT2. This patch do the samething in kernel and expose them in cpuinfo so applications can probe supported ASEs at runtime. Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com> Cc: Huacai Chen <chenhc@lemote.com> Cc: Yunqiang Su <ysu@wavecomp.com> Cc: stable@vger.kernel.org # v4.14+ Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: linux-mips@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-07MIPS: Ingenic: Disable broken BTB lookup optimization.Zhou Yanjie1-0/+7
[ Upstream commit 053951dda71ecb4b554a2cdbe26f5f6f9bee9dd2 ] In order to further reduce power consumption, the XBurst core by default attempts to avoid branch target buffer lookups by detecting & special casing loops. This feature will cause BogoMIPS and lpj calculate in error. Set cp0 config7 bit 4 to disable this feature. Signed-off-by: Zhou Yanjie <zhouyanjie@zoho.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: ralf@linux-mips.org Cc: paul@crapouillou.net Cc: jhogan@kernel.org Cc: malat@debian.org Cc: gregkh@linuxfoundation.org Cc: tglx@linutronix.de Cc: allison@lohutok.net Cc: syq@debian.org Cc: chenhc@lemote.com Cc: jiaxun.yang@flygoat.com Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-08-29mips: fix cacheinfoVladimir Kondratiev1-0/+2
[ Upstream commit b8bea8a5e5d942e62203416ab41edecaed4fda02 ] Because CONFIG_OF defined for MIPS, cacheinfo attempts to fill information from DT, ignoring data filled by architecture routine. This leads to error reported cacheinfo: Unable to detect cache hierarchy for CPU 0 Way to fix this provided in commit fac51482577d ("drivers: base: cacheinfo: fix x86 with CONFIG_OF enabled") Utilize same mechanism to report that cacheinfo set by architecture specific function Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@linux.intel.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-08-29MIPS: kernel: only use i8253 clocksource with periodic clockeventThomas Bogendoerfer1-1/+2
[ Upstream commit a07e3324538a989b7cdbf2c679be6a7f9df2544f ] i8253 clocksource needs a free running timer. This could only be used, if i8253 clockevent is set up as periodic. Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-06-25MIPS: uprobes: remove set but not used variable 'epc'YueHaibing1-3/+0
[ Upstream commit f532beeeff0c0a3586cc15538bc52d249eb19e7c ] Fixes gcc '-Wunused-but-set-variable' warning: arch/mips/kernel/uprobes.c: In function 'arch_uprobe_pre_xol': arch/mips/kernel/uprobes.c:115:17: warning: variable 'epc' set but not used [-Wunused-but-set-variable] It's never used since introduction in commit 40e084a506eb ("MIPS: Add uprobes support.") Signed-off-by: YueHaibing <yuehaibing@huawei.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: <ralf@linux-mips.org> Cc: <jhogan@kernel.org> Cc: <linux-kernel@vger.kernel.org> Cc: <linux-mips@vger.kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-06-15mips: Make sure dt memory regions are validSerge Semin1-1/+13
[ Upstream commit 93fa5b280761a4dbb14c5330f260380385ab2b49 ] There are situations when memory regions coming from dts may be too big for the platform physical address space. This especially concerns XPA-capable systems. Bootloader may determine more than 4GB memory available and pass it to the kernel over dts memory node, while kernel is built without XPA/64BIT support. In this case the region may either simply be truncated by add_memory_region() method or by u64->phys_addr_t type casting. But in worst case the method can even drop the memory region if it exceeds PHYS_ADDR_MAX size. So lets make sure the retrieved from dts memory regions are valid, and if some of them aren't, just manually truncate them with a warning printed out. Signed-off-by: Serge Semin <fancer.lancer@gmail.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Thomas Bogendoerfer <tbogendoerfer@suse.de> Cc: Huacai Chen <chenhc@lemote.com> Cc: Stefan Agner <stefan@agner.ch> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Alexandre Belloni <alexandre.belloni@bootlin.com> Cc: Juergen Gross <jgross@suse.com> Cc: Serge Semin <Sergey.Semin@t-platforms.ru> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-06-04jump_label: move 'asm goto' support test to KconfigMasahiro Yamada1-4/+0
commit e9666d10a5677a494260d60d1fa0b73cc7646eb3 upstream. Currently, CONFIG_JUMP_LABEL just means "I _want_ to use jump label". The jump label is controlled by HAVE_JUMP_LABEL, which is defined like this: #if defined(CC_HAVE_ASM_GOTO) && defined(CONFIG_JUMP_LABEL) # define HAVE_JUMP_LABEL #endif We can improve this by testing 'asm goto' support in Kconfig, then make JUMP_LABEL depend on CC_HAS_ASM_GOTO. Ugly #ifdef HAVE_JUMP_LABEL will go away, and CONFIG_JUMP_LABEL will match to the real kernel capability. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc) Tested-by: Sedat Dilek <sedat.dilek@gmail.com> [nc: Fix trivial conflicts in 4.19 arch/xtensa/kernel/jump_label.c doesn't exist yet Ensured CC_HAVE_ASM_GOTO and HAVE_JUMP_LABEL were sufficiently eliminated] Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-25MIPS: perf: Fix build with CONFIG_CPU_BMIPS5000 enabledFlorian Fainelli1-18/+3
commit 1b1f01b653b408ebe58fec78c566d1075d285c64 upstream. arch/mips/kernel/perf_event_mipsxx.c: In function 'mipsxx_pmu_enable_event': arch/mips/kernel/perf_event_mipsxx.c:326:21: error: unused variable 'event' [-Werror=unused-variable] struct perf_event *event = container_of(evt, struct perf_event, hw); ^~~~~ Fix this by making use of IS_ENABLED() to simplify the code and avoid unnecessary ifdefery. Fixes: 84002c88599d ("MIPS: perf: Fix perf with MT counting other threads") Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: linux-mips@linux-mips.org Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: linux-kernel@vger.kernel.org Cc: linux-mips@vger.kernel.org Cc: stable@vger.kernel.org # v4.18+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-10MIPS: KGDB: fix kgdb support for SMP platforms.Chong Qiao1-1/+2
[ Upstream commit ab8a6d821179ab9bea1a9179f535ccba6330c1ed ] KGDB_call_nmi_hook is called by other cpu through smp call. MIPS smp call is processed in ipi irq handler and regs is saved in handle_int. So kgdb_call_nmi_hook get regs by get_irq_regs and regs will be passed to kgdb_cpu_enter. Signed-off-by: Chong Qiao <qiaochong@loongson.cn> Reviewed-by: Douglas Anderson <dianders@chromium.org> Acked-by: Daniel Thompson <daniel.thompson@linaro.org> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Christophe Leroy <christophe.leroy@c-s.fr> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: QiaoChong <qiaochong@loongson.cn> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-05-02MIPS: scall64-o32: Fix indirect syscall number loadAurelien Jarno1-1/+1
commit 79b4a9cf0e2ea8203ce777c8d5cfa86c71eae86e upstream. Commit 4c21b8fd8f14 (MIPS: seccomp: Handle indirect system calls (o32)) added indirect syscall detection for O32 processes running on MIPS64, but it did not work correctly for big endian kernel/processes. The reason is that the syscall number is loaded from ARG1 using the lw instruction while this is a 64-bit value, so zero is loaded instead of the syscall number. Fix the code by using the ld instruction instead. When running a 32-bit processes on a 64 bit CPU, the values are properly sign-extended, so it ensures the value passed to syscall_trace_enter is correct. Recent systemd versions with seccomp enabled whitelist the getpid syscall for their internal processes (e.g. systemd-journald), but call it through syscall(SYS_getpid). This fix therefore allows O32 big endian systems with a 64-bit kernel to run recent systemd versions. Signed-off-by: Aurelien Jarno <aurelien@aurel32.net> Cc: <stable@vger.kernel.org> # v3.15+ Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-27MIPS: Ensure ELF appended dtb is relocatedYasha Cherikovsky1-5/+7
commit 3f0a53bc6482fb09770982a8447981260ea258dc upstream. This fixes booting with the combination of CONFIG_RELOCATABLE=y and CONFIG_MIPS_ELF_APPENDED_DTB=y. Sections that appear after the relocation table are not relocated on system boot (except .bss, which has special handling). With CONFIG_MIPS_ELF_APPENDED_DTB, the dtb is part of the vmlinux ELF, so it must be relocated together with everything else. Fixes: 069fd766271d ("MIPS: Reserve space for relocation table") Signed-off-by: Yasha Cherikovsky <yasha.che3@gmail.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Burton <paul.burton@mips.com> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v4.7+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-13MIPS: Remove function size check in get_frame_info()Jun-Ru Chang1-4/+3
[ Upstream commit 2b424cfc69728224fcb5fad138ea7260728e0901 ] Patch (b6c7a324df37b "MIPS: Fix get_frame_info() handling of microMIPS function size.") introduces additional function size check for microMIPS by only checking insn between ip and ip + func_size. However, func_size in get_frame_info() is always 0 if KALLSYMS is not enabled. This causes get_frame_info() to return immediately without calculating correct frame_size, which in turn causes "Can't analyze schedule() prologue" warning messages at boot time. This patch removes func_size check, and let the frame_size check run up to 128 insns for both MIPS and microMIPS. Signed-off-by: Jun-Ru Chang <jrjang@realtek.com> Signed-off-by: Tony Wu <tonywu@realtek.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Fixes: b6c7a324df37b ("MIPS: Fix get_frame_info() handling of microMIPS function size.") Cc: <ralf@linux-mips.org> Cc: <jhogan@kernel.org> Cc: <macro@mips.com> Cc: <yamada.masahiro@socionext.com> Cc: <peterz@infradead.org> Cc: <mingo@kernel.org> Cc: <linux-mips@vger.kernel.org> Cc: <linux-kernel@vger.kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-03-10MIPS: irq: Allocate accurate order pages for irq stackLiu Xiang1-2/+2
commit 72faa7a773ca59336f3c889e878de81445c5a85c upstream. The irq_pages is the number of pages for irq stack, but not the order which is needed by __get_free_pages(). We can use get_order() to calculate the accurate order. Signed-off-by: Liu Xiang <liu.xiang6@zte.com.cn> Signed-off-by: Paul Burton <paul.burton@mips.com> Fixes: fe8bd18ffea5 ("MIPS: Introduce irq_stack") Cc: linux-mips@vger.kernel.org Cc: stable@vger.kernel.org # v4.11+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-05MIPS: fix truncation in __cmpxchg_small for short valuesMichael Clark1-2/+1
commit 94ee12b507db8b5876e31c9d6c9d84f556a4b49f upstream. __cmpxchg_small erroneously uses u8 for load comparison which can be either char or short. This patch changes the local variable to u32 which is sufficiently sized, as the loaded value is already masked and shifted appropriately. Using an integer size avoids any unnecessary canonicalization from use of non native widths. This patch is part of a series that adapts the MIPS small word atomics code for xchg and cmpxchg on short and char to RISC-V. Cc: RISC-V Patches <patches@groups.riscv.org> Cc: Linux RISC-V <linux-riscv@lists.infradead.org> Cc: Linux MIPS <linux-mips@linux-mips.org> Signed-off-by: Michael Clark <michaeljclark@mac.com> [paul.burton@mips.com: - Fix varialble typo per Jonas Gorski. - Consolidate load variable with other declarations.] Signed-off-by: Paul Burton <paul.burton@mips.com> Fixes: 3ba7f44d2b19 ("MIPS: cmpxchg: Implement 1 byte & 2 byte cmpxchg()") Cc: stable@vger.kernel.org # v4.13+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-02-15mips: cm: reprime error causeVladimir Kondratiev1-1/+1
commit 05dc6001af0630e200ad5ea08707187fe5537e6d upstream. Accordingly to the documentation ---cut--- The GCR_ERROR_CAUSE.ERR_TYPE field and the GCR_ERROR_MULT.ERR_TYPE fields can be cleared by either a reset or by writing the current value of GCR_ERROR_CAUSE.ERR_TYPE to the GCR_ERROR_CAUSE.ERR_TYPE register. ---cut--- Do exactly this. Original value of cm_error may be safely written back; it clears error cause and keeps other bits untouched. Fixes: 3885c2b463f6 ("MIPS: CM: Add support for reporting CM cache errors") Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@linux.intel.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v4.3+ Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-01-09MIPS: math-emu: Write-protect delay slot emulation pagesPaul Burton1-2/+2
commit adcc81f148d733b7e8e641300c5590a2cdc13bf3 upstream. Mapping the delay slot emulation page as both writeable & executable presents a security risk, in that if an exploit can write to & jump into the page then it can be used as an easy way to execute arbitrary code. Prevent this by mapping the page read-only for userland, and using access_process_vm() with the FOLL_FORCE flag to write to it from mips_dsemul(). This will likely be less efficient due to copy_to_user_page() performing cache maintenance on a whole page, rather than a single line as in the previous use of flush_cache_sigtramp(). However this delay slot emulation code ought not to be running in any performance critical paths anyway so this isn't really a problem, and we can probably do better in copy_to_user_page() anyway in future. A major advantage of this approach is that the fix is small & simple to backport to stable kernels. Reported-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Paul Burton <paul.burton@mips.com> Fixes: 432c6bacbd0c ("MIPS: Use per-mm page to execute branch delay slot instructions") Cc: stable@vger.kernel.org # v4.8+ Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: Rich Felker <dalias@libc.org> Cc: David Daney <david.daney@cavium.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-12-05MIPS: function_graph: Simplify with function_graph_enter()Steven Rostedt (VMware)1-12/+2
commit 8712b27c5723c26400a2b350faf1d6d9fd7ffaad upstream. The function_graph_enter() function does the work of calling the function graph hook function and the management of the shadow stack, simplifying the work done in the architecture dependent prepare_ftrace_return(). Have MIPS use the new code, and remove the shadow stack management as well as having to set up the trace structure. This is needed to prepare for a fix of a design bug on how the curr_ret_stack is used. Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Paul Burton <paul.burton@mips.com> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@linux-mips.org Cc: stable@kernel.org Fixes: 03274a3ffb449 ("tracing/fgraph: Adjust fgraph depth before calling trace return callback") Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-11-21MIPS: kexec: Mark CPU offline before disabling local IRQDengcheng Zhu2-0/+6
[ Upstream commit dc57aaf95a516f70e2d527d8287a0332c481a226 ] After changing CPU online status, it will not be sent any IPIs such as in __flush_cache_all() on software coherency systems. Do this before disabling local IRQ. Signed-off-by: Dengcheng Zhu <dzhu@wavecomp.com> Signed-off-by: Paul Burton <paul.burton@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/20571/ Cc: pburton@wavecomp.com Cc: ralf@linux-mips.org Cc: linux-mips@linux-mips.org Cc: rachel.mozes@intel.com Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-09-28MIPS: Fix CONFIG_CMDLINE handlingPaul Burton1-20/+28
Commit 8ce355cf2e38 ("MIPS: Setup boot_command_line before plat_mem_setup") fixed a problem for systems which have CONFIG_CMDLINE_BOOL=y & use a DT with a chosen node that has either no bootargs property or an empty one. In this configuration early_init_dt_scan_chosen() copies CONFIG_CMDLINE into boot_command_line, but the MIPS code doesn't know this so it appends CONFIG_CMDLINE (via builtin_cmdline) to boot_command_line again. The result is that boot_command_line contains the arguments from CONFIG_CMDLINE twice. That commit took the approach of simply setting up boot_command_line from the MIPS code before early_init_dt_scan_chosen() runs, causing it not to copy CONFIG_CMDLINE to boot_command_line if a chosen node with no bootargs property is found. Unfortunately this is problematic for systems which do have a non-empty bootargs property & CONFIG_CMDLINE_BOOL=y. There early_init_dt_scan_chosen() will overwrite boot_command_line with the arguments from DT, which means we lose those from CONFIG_CMDLINE entirely. This breaks CONFIG_MIPS_CMDLINE_DTB_EXTEND. If we have CONFIG_MIPS_CMDLINE_FROM_BOOTLOADER or CONFIG_MIPS_CMDLINE_BUILTIN_EXTEND selected and the DT has a bootargs property which we should ignore, it will instead be honoured breaking those configurations too. Fix this by reverting commit 8ce355cf2e38 ("MIPS: Setup boot_command_line before plat_mem_setup") to restore the former behaviour, and fixing the CONFIG_CMDLINE duplication issue by initializing boot_command_line to a non-empty string that early_init_dt_scan_chosen() will not overwrite with CONFIG_CMDLINE. This is a little ugly, but cleanup in this area is on its way. In the meantime this is at least easy to backport & contains the ugliness within arch/mips/. Signed-off-by: Paul Burton <paul.burton@mips.com> Fixes: 8ce355cf2e38 ("MIPS: Setup boot_command_line before plat_mem_setup") References: https://patchwork.linux-mips.org/patch/18804/ Patchwork: https://patchwork.linux-mips.org/patch/20813/ Cc: Frank Rowand <frowand.list@gmail.com> Cc: Jaedon Shin <jaedon.shin@gmail.com> Cc: Mathieu Malaterre <malat@debian.org> Cc: Rob Herring <robh+dt@kernel.org> Cc: devicetree@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org # v4.16+
2018-09-28MIPS: VDSO: Always map near top of user memoryPaul Burton2-1/+42
When using the legacy mmap layout, for example triggered using ulimit -s unlimited, get_unmapped_area() fills memory from bottom to top starting from a fairly low address near TASK_UNMAPPED_BASE. This placement is suboptimal if the user application wishes to allocate large amounts of heap memory using the brk syscall. With the VDSO being located low in the user's virtual address space, the amount of space available for access using brk is limited much more than it was prior to the introduction of the VDSO. For example: # ulimit -s unlimited; cat /proc/self/maps 00400000-004ec000 r-xp 00000000 08:00 71436 /usr/bin/coreutils 004fc000-004fd000 rwxp 000ec000 08:00 71436 /usr/bin/coreutils 004fd000-0050f000 rwxp 00000000 00:00 0 00cc3000-00ce4000 rwxp 00000000 00:00 0 [heap] 2ab96000-2ab98000 r--p 00000000 00:00 0 [vvar] 2ab98000-2ab99000 r-xp 00000000 00:00 0 [vdso] 2ab99000-2ab9d000 rwxp 00000000 00:00 0 ... Resolve this by adjusting STACK_TOP to reserve space for the VDSO & providing an address hint to get_unmapped_area() causing it to use this space even when using the legacy mmap layout. We reserve enough space for the VDSO, plus 1MB or 256MB for 32 bit & 64 bit systems respectively within which we randomize the VDSO base address. Previously this randomization was taken care of by the mmap base address randomization performed by arch_mmap_rnd(). The 1MB & 256MB sizes are somewhat arbitrary but chosen such that we have some randomization without taking up too much of the user's virtual address space, which is often in short supply for 32 bit systems. With this the VDSO is always mapped at a high address, leaving lots of space for statically linked programs to make use of brk: # ulimit -s unlimited; cat /proc/self/maps 00400000-004ec000 r-xp 00000000 08:00 71436 /usr/bin/coreutils 004fc000-004fd000 rwxp 000ec000 08:00 71436 /usr/bin/coreutils 004fd000-0050f000 rwxp 00000000 00:00 0 00c28000-00c49000 rwxp 00000000 00:00 0 [heap] ... 7f67c000-7f69d000 rwxp 00000000 00:00 0 [stack] 7f7fc000-7f7fd000 rwxp 00000000 00:00 0 7fcf1000-7fcf3000 r--p 00000000 00:00 0 [vvar] 7fcf3000-7fcf4000 r-xp 00000000 00:00 0 [vdso] Signed-off-by: Paul Burton <paul.burton@mips.com> Reported-by: Huacai Chen <chenhc@lemote.com> Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO") Cc: Huacai Chen <chenhc@lemote.com> Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org # v4.4+
2018-08-31MIPS: VDSO: Match data page cache colouring when D$ aliasesPaul Burton1-0/+20
When a system suffers from dcache aliasing a user program may observe stale VDSO data from an aliased cache line. Notably this can break the expectation that clock_gettime(CLOCK_MONOTONIC, ...) is, as its name suggests, monotonic. In order to ensure that users observe updates to the VDSO data page as intended, align the user mappings of the VDSO data page such that their cache colouring matches that of the virtual address range which the kernel will use to update the data page - typically its unmapped address within kseg0. This ensures that we don't introduce aliasing cache lines for the VDSO data page, and therefore that userland will observe updates without requiring cache invalidation. Signed-off-by: Paul Burton <paul.burton@mips.com> Reported-by: Hauke Mehrtens <hauke@hauke-m.de> Reported-by: Rene Nielsen <rene.nielsen@microsemi.com> Reported-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Fixes: ebb5e78cc634 ("MIPS: Initial implementation of a VDSO") Patchwork: https://patchwork.linux-mips.org/patch/20344/ Tested-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Tested-by: Hauke Mehrtens <hauke@hauke-m.de> Cc: James Hogan <jhogan@kernel.org> Cc: linux-mips@linux-mips.org Cc: stable@vger.kernel.org # v4.4+
2018-08-23Merge tag 'mips_4.19_2' of ↵Linus Torvalds1-3/+1
git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux Pull MIPS fixes from Paul Burton: - Fix microMIPS build failures by adding a .insn directive to the barrier_before_unreachable() asm statement in order to convince the toolchain that the asm statement is a valid branch target rather than a bogus attempt to switch ISA. - Clean up our declarations of TLB functions that we overwrite with generated code in order to prevent the compiler making assumptions about alignment that cause microMIPS kernels built with GCC 7 & above to die early during boot. - Fix up a regression for MIPS32 kernels which slipped into the main MIPS pull for 4.19, causing CONFIG_32BIT=y kernels to contain inappropriate MIPS64 instructions. - Extend our existing workaround for MIPSr6 builds that end up using the __multi3 intrinsic to GCC 7 & below, rather than just GCC 7. * tag 'mips_4.19_2' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: MIPS: lib: Provide MIPS64r6 __multi3() for GCC < 7 MIPS: Workaround GCC __builtin_unreachable reordering bug compiler.h: Allow arch-specific asm/compiler.h MIPS: Avoid move psuedo-instruction whilst using MIPS_ISA_LEVEL MIPS: Consistently declare TLB functions MIPS: Export tlbmiss_handler_setup_pgd near its definition
2018-08-20Merge tag 'trace-v4.19' of ↵Linus Torvalds1-1/+1
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing updates from Steven Rostedt: - Restructure of lockdep and latency tracers This is the biggest change. Joel Fernandes restructured the hooks from irqs and preemption disabling and enabling. He got rid of a lot of the preprocessor #ifdef mess that they caused. He turned both lockdep and the latency tracers to use trace events inserted in the preempt/irqs disabling paths. But unfortunately, these started to cause issues in corner cases. Thus, parts of the code was reverted back to where lockdep and the latency tracers just get called directly (without using the trace events). But because the original change cleaned up the code very nicely we kept that, as well as the trace events for preempt and irqs disabling, but they are limited to not being called in NMIs. - Have trace events use SRCU for "rcu idle" calls. This was required for the preempt/irqs off trace events. But it also had to not allow them to be called in NMI context. Waiting till Paul makes an NMI safe SRCU API. - New notrace SRCU API to allow trace events to use SRCU. - Addition of mcount-nop option support - SPDX headers replacing GPL templates. - Various other fixes and clean ups. - Some fixes are marked for stable, but were not fully tested before the merge window opened. * tag 'trace-v4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (44 commits) tracing: Fix SPDX format headers to use C++ style comments tracing: Add SPDX License format tags to tracing files tracing: Add SPDX License format to bpf_trace.c blktrace: Add SPDX License format header s390/ftrace: Add -mfentry and -mnop-mcount support tracing: Add -mcount-nop option support tracing: Avoid calling cc-option -mrecord-mcount for every Makefile tracing: Handle CC_FLAGS_FTRACE more accurately Uprobe: Additional argument arch_uprobe to uprobe_write_opcode() Uprobes: Simplify uprobe_register() body tracepoints: Free early tracepoints after RCU is initialized uprobes: Use synchronize_rcu() not synchronize_sched() tracing: Fix synchronizing to event changes with tracepoint_synchronize_unregister() ftrace: Remove unused pointer ftrace_swapper_pid tracing: More reverting of "tracing: Centralize preemptirq tracepoints and unify their usage" tracing/irqsoff: Handle preempt_count for different configs tracing: Partial revert of "tracing: Centralize preemptirq tracepoints and unify their usage" tracing: irqsoff: Account for additional preempt_disable trace: Use rcu_dereference_raw for hooks from trace-event subsystem tracing/kprobes: Fix within_notrace_func() to check only notrace functions ...
2018-08-13Merge tag 'mips_4.19' of ↵Linus Torvalds15-114/+424
git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux Pull MIPS updates from Paul Burton: "Here are the main MIPS changes for 4.19. An overview of the general architecture changes: - Massive DMA ops refactoring from Christoph Hellwig (huzzah for deleting crufty code!). - We introduce NT_MIPS_DSP & NT_MIPS_FP_MODE ELF notes & corresponding regsets to expose DSP ASE & floating point mode state respectively, both for live debugging & core dumps. - We better optimize our code by hard-coding cpu_has_* macros at compile time where their values are known due to the ISA revision that the kernel build is targeting. - The EJTAG exception handler now better handles SMP systems, where it was previously possible for CPUs to clobber a register value saved by another CPU. - Our implementation of memset() gained a couple of fixes for MIPSr6 systems to return correct values in some cases where stores fault. - We now implement ioremap_wc() using the uncached-accelerated cache coherency attribute where supported, which is detected during boot, and fall back to plain uncached access where necessary. The MIPS-specific (and unused in tree) ioremap_uncached_accelerated() & ioremap_cacheable_cow() are removed. - The prctl(PR_SET_FP_MODE, ...) syscall is better supported for SMP systems by reworking the way we ensure remote CPUs that may be running threads within the affected process switch mode. - Systems using the MIPS Coherence Manager will now set the MIPS_IC_SNOOPS_REMOTE flag to avoid some unnecessary cache maintenance overhead when flushing the icache. - A few fixes were made for building with clang/LLVM, which now sucessfully builds kernels for many of our platforms. - Miscellaneous cleanups all over. And some platform-specific changes: - ar7 gained stubs for a few clock API functions to fix build failures for some drivers. - ath79 gained support for a few new SoCs, a few fixes & better gpio-keys support. - Ci20 now exposes its SPI bus using the spi-gpio driver. - The generic platform can now auto-detect a suitable value for PHYS_OFFSET based upon the memory map described by the device tree, allowing us to avoid wasting memory on page book-keeping for systems where RAM starts at a non-zero physical address. - Ingenic systems using the jz4740 platform code now link their vmlinuz higher to allow for kernels of a realistic size. - Loongson32 now builds the kernel targeting MIPSr1 rather than MIPSr2 to avoid CPU errata. - Loongson64 gains a couple of fixes, a workaround for a write buffering issue & support for the Loongson 3A R3.1 CPU. - Malta now uses the piix4-poweroff driver to handle powering down. - Microsemi Ocelot gained support for its SPI bus & NOR flash, its second MDIO bus and can now be supported by a FIT/.itb image. - Octeon saw a bunch of header cleanups which remove a lot of duplicate or unused code" * tag 'mips_4.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: (123 commits) MIPS: Remove remnants of UASM_ISA MIPS: netlogic: xlr: Remove erroneous check in nlm_fmn_send() MIPS: VDSO: Force link endianness MIPS: Always specify -EB or -EL when using clang MIPS: Use dins to simplify __write_64bit_c0_split() MIPS: Use read-write output operand in __write_64bit_c0_split() MIPS: Avoid using array as parameter to write_c0_kpgd() MIPS: vdso: Allow clang's --target flag in VDSO cflags MIPS: genvdso: Remove GOT checks MIPS: Remove obsolete MIPS checks for DST node "chosen@0" MIPS: generic: Remove input symbols from defconfig MIPS: Delete unused code in linux32.c MIPS: Remove unused sys_32_mmap2 MIPS: Remove nabi_no_regargs mips: dts: mscc: enable spi and NOR flash support on ocelot PCB123 mips: dts: mscc: Add spi on Ocelot MIPS: Loongson: Merge load addresses MIPS: Loongson: Set Loongson32 to MIPS32R1 MIPS: mscc: ocelot: add interrupt controller properties to GPIO controller MIPS: generic: Select MIPS_AUTO_PFN_OFFSET ...
2018-08-13Uprobe: Additional argument arch_uprobe to uprobe_write_opcode()Ravi Bangoria1-1/+1
Add addition argument 'arch_uprobe' to uprobe_write_opcode(). We need this in later set of patches. Link: http://lkml.kernel.org/r/20180809041856.1547-3-ravi.bangoria@linux.ibm.com Reviewed-by: Song Liu <songliubraving@fb.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2018-08-10MIPS: Consistently declare TLB functionsPaul Burton1-3/+1
Since at least the beginning of the git era we've declared our TLB exception handling functions inconsistently. They're actually functions, but we declare them as arrays of u32 where each u32 is an encoded instruction. This has always been the case for arch/mips/mm/tlbex.c, and has also been true for arch/mips/kernel/traps.c since commit 86a1708a9d54 ("MIPS: Make tlb exception handler definitions and declarations match.") which aimed for consistency but did so by consistently making the our C code inconsistent with our assembly. This is all usually harmless, but when using GCC 7 or newer to build a kernel targeting microMIPS (ie. CONFIG_CPU_MICROMIPS=y) it becomes problematic. With microMIPS bit 0 of the program counter indicates the ISA mode. When bit 0 is zero instructions are decoded using the standard MIPS32 or MIPS64 ISA. When bit 0 is one instructions are decoded using microMIPS. This means that function pointers become odd - their least significant bit is one for microMIPS code. We work around this in cases where we need to access code using loads & stores with our msk_isa16_mode() macro which simply clears bit 0 of the value it is given: #define msk_isa16_mode(x) ((x) & ~0x1) For example we do this for our TLB load handler in build_r4000_tlb_load_handler(): u32 *p = (u32 *)msk_isa16_mode((ulong)handle_tlbl); We then write code to p, expecting it to be suitably aligned (our LEAF macro aligns functions on 4 byte boundaries, so (ulong)handle_tlbl will give a value one greater than a multiple of 4 - ie. the start of a function on a 4 byte boundary, with the ISA mode bit 0 set). This worked fine up to GCC 6, but GCC 7 & onwards is smart enough to presume that handle_tlbl which we declared as an array of u32s must be aligned sufficiently that bit 0 of its address will never be set, and as a result optimize out msk_isa16_mode(). This leads to p having an address with bit 0 set, and when we go on to attempt to store code at that address we take an address error exception due to the unaligned memory access. This leads to an exception prior to the kernel having configured its own exception handlers, so we jump to whatever handlers the bootloader configured. In the case of QEMU this results in a silent hang, since it has no useful general exception vector. Fix this by consistently declaring our TLB-related functions as functions. For handle_tlbl(), handle_tlbs() & handle_tlbm() we do this in asm/tlbex.h & we make use of the existing declaration of tlbmiss_handler_setup_pgd() in asm/mmu_context.h. Our TLB handler generation code in arch/mips/mm/tlbex.c is adjusted to deal with these definitions, in most cases simply by casting the function pointers to u32 pointers. This allows us to include asm/mmu_context.h in arch/mips/mm/tlbex.c to get the definitions of tlbmiss_handler_setup_pgd & pgd_current, removing some needless duplication. Consistently using msk_isa16_mode() on function pointers means we no longer need the tlbmiss_handler_setup_pgd_start symbol so that is removed entirely. Now that we're declaring our functions as functions GCC stops optimizing out msk_isa16_mode() & a microMIPS kernel built with either GCC 7.3.0 or 8.1.0 boots successfully. Signed-off-by: Paul Burton <paul.burton@mips.com>
2018-08-01MIPS: Delete unused code in linux32.cPaul Burton1-19/+0
The A() & AA() macros have been unused since commit 05e4396651ca ("[MIPS] Use SYSVIPC_COMPAT to fix various problems on N32"), which switched to the more standard compat_ptr(). RLIM_INFINITY32, RESOURCE32() & struct rlimit32 have been present but unused since the beginning of the git era. Remove the dead code. Signed-off-by: Paul Burton <paul.burton@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/20108/ Cc: James Hogan <jhogan@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org
2018-08-01MIPS: Remove unused sys_32_mmap2Paul Burton1-10/+0
The sys_32_mmap2 function has been unused since we started using syscall wrappers in commit dbda6ac08976 ("MIPS: CVE-2009-0029: Enable syscall wrappers."), and is indeed identical to the sys_mips_mmap2 function that replaced it in sys32_call_table. Remove the dead code. Signed-off-by: Paul Burton <paul.burton@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/20107/ Cc: James Hogan <jhogan@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org
2018-08-01MIPS: Remove nabi_no_regargsPaul Burton3-25/+35
Our sigreturn functions make use of a macro named nabi_no_regargs to declare 8 dummy arguments to a function, forcing the compiler to expect a pt_regs structure on the stack rather than in argument registers. This is an ugly hack which unnecessarily causes these sigreturn functions to need to care about the calling convention of the ABI the kernel is built for. Although this is abstracted via nabi_no_regargs, it's still ugly & unnecessary. Remove nabi_no_regargs & the struct pt_regs argument from sigreturn functions, and instead use current_pt_regs() to find the struct pt_regs on the stack, which works cleanly regardless of ABI. Signed-off-by: Paul Burton <paul.burton@mips.com> Patchwork: https://patchwork.linux-mips.org/patch/20106/ Cc: James Hogan <jhogan@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org
2018-07-30MIPS: Allow auto-dection of ARCH_PFN_OFFSET & PHYS_OFFSETPaul Burton1-2/+12
On systems where physical memory begins at a non-zero address, defining PHYS_OFFSET (which influences ARCH_PFN_OFFSET) can save us time & memory by avoiding book-keeping for pages from address zero to the start of memory. Some MIPS platforms already make use of this, but with the definition of PHYS_OFFSET being compile-time constant it hasn't been possible to enable this optimization for a kernel which may run on systems with varying physical memory base addresses. Introduce a new Kconfig option CONFIG_MIPS_AUTO_PFN_OFFSET which, when enabled, makes ARCH_PFN_OFFSET a variable & detects it from the boot memory map (which for example may have been populated from DT). The relationship with PHYS_OFFSET is reversed, with PHYS_OFFSET now being based on ARCH_PFN_OFFSET. This is because ARCH_PFN_OFFSET is used far more often, so avoiding the need for runtime calculation gives us a smaller impact on kernel text size (0.1% rather than 0.15% for 64r6el_