- 03 Dec, 2020 15 commits
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Christophe Leroy authored
Provides __kernel_clock_gettime64() on vdso32. This is the 64 bits version of __kernel_clock_gettime() which is y2038 compliant. Signed-off-by:
Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20201126131006.2431205-9-mpe@ellerman.id.au
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Christophe Leroy authored
With the C VDSO, the performance is slightly lower, but it is worth it as it will ease maintenance and evolution, and also brings clocks that are not supported with the ASM VDSO. On an 8xx at 132 MHz, vdsotest with the ASM VDSO: gettimeofday: vdso: 828 nsec/call clock-getres-realtime-coarse: vdso: 391 nsec/call clock-gettime-realtime-coarse: vdso: 614 nsec/call clock-getres-realtime: vdso: 460 nsec/call clock-gettime-realtime: vdso: 876 nsec/call clock-getres-monotonic-coarse: vdso: 399 nsec/call clock-gettime-monotonic-coarse: vdso: 691 nsec/call clock-getres-monotonic: vdso: 460 nsec/call clock-gettime-monotonic: vdso: 1026 nsec/call On an 8xx at 132 MHz, vdsotest with the C VDSO: gettimeofday: vdso: 955 nsec/call clock-getres-realtime-coarse: vdso: 545 nsec/call clock-gettime-realtime-coarse: vdso: 592 nsec/call clock-getres-realtime: vdso: 545 nsec/call clock-gettime-realtime: vdso: 941 nsec/call clock-getres-monotonic-coarse: vdso: 545 nsec/call clock-gettime-monotonic-coarse: vdso: 591 nsec/call clock-getres-monotonic: vdso: 545 nsec/call clock-gettime-monotonic: vdso: 940 nsec/call It is even better for gettime with monotonic clocks. Unsupported clocks with ASM VDSO: clock-gettime-boottime: vdso: 3851 nsec/call clock-gettime-tai: vdso: 3852 nsec/call clock-gettime-monotonic-raw: vdso: 3396 nsec/call Same clocks with C VDSO: clock-gettime-tai: vdso: 941 nsec/call clock-gettime-monotonic-raw: vdso: 1001 nsec/call clock-gettime-monotonic-coarse: vdso: 591 nsec/call On an 8321E at 333 MHz, vdsotest with the ASM VDSO: gettimeofday: vdso: 220 nsec/call clock-getres-realtime-coarse: vdso: 102 nsec/call clock-gettime-realtime-coarse: vdso: 178 nsec/call clock-getres-realtime: vdso: 129 nsec/call clock-gettime-realtime: vdso: 235 nsec/call clock-getres-monotonic-coarse: vdso: 105 nsec/call clock-gettime-monotonic-coarse: vdso: 208 nsec/call clock-getres-monotonic: vdso: 129 nsec/call clock-gettime-monotonic: vdso: 274 nsec/call On an 8321E at 333 MHz, vdsotest with the C VDSO: gettimeofday: vdso: 272 nsec/call clock-getres-realtime-coarse: vdso: 160 nsec/call clock-gettime-realtime-coarse: vdso: 184 nsec/call clock-getres-realtime: vdso: 166 nsec/call clock-gettime-realtime: vdso: 281 nsec/call clock-getres-monotonic-coarse: vdso: 160 nsec/call clock-gettime-monotonic-coarse: vdso: 184 nsec/call clock-getres-monotonic: vdso: 169 nsec/call clock-gettime-monotonic: vdso: 275 nsec/call On a Power9 Nimbus DD2.2 at 3.8GHz, with the ASM VDSO: clock-gettime-monotonic: vdso: 35 nsec/call clock-getres-monotonic: vdso: 16 nsec/call clock-gettime-monotonic-coarse: vdso: 18 nsec/call clock-getres-monotonic-coarse: vdso: 522 nsec/call clock-gettime-monotonic-raw: vdso: 598 nsec/call clock-getres-monotonic-raw: vdso: 520 nsec/call clock-gettime-realtime: vdso: 34 nsec/call clock-getres-realtime: vdso: 16 nsec/call clock-gettime-realtime-coarse: vdso: 18 nsec/call clock-getres-realtime-coarse: vdso: 517 nsec/call getcpu: vdso: 8 nsec/call gettimeofday: vdso: 25 nsec/call And with the C VDSO: clock-gettime-monotonic: vdso: 37 nsec/call clock-getres-monotonic: vdso: 20 nsec/call clock-gettime-monotonic-coarse: vdso: 21 nsec/call clock-getres-monotonic-coarse: vdso: 19 nsec/call clock-gettime-monotonic-raw: vdso: 38 nsec/call clock-getres-monotonic-raw: vdso: 20 nsec/call clock-gettime-realtime: vdso: 37 nsec/call clock-getres-realtime: vdso: 20 nsec/call clock-gettime-realtime-coarse: vdso: 20 nsec/call clock-getres-realtime-coarse: vdso: 19 nsec/call getcpu: vdso: 8 nsec/call gettimeofday: vdso: 28 nsec/call Signed-off-by:
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Christophe Leroy authored
On PPC64, the TOC pointer needs to be saved and restored. Suggested-by:
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Christophe Leroy authored
Prepare for switching VDSO to generic C implementation in following patch. Here, we: - Prepare the helpers to call the C VDSO functions - Prepare the required callbacks for the C VDSO functions - Prepare the clocksource.h files to define VDSO_ARCH_CLOCKMODES - Add the C trampolines to the generic C VDSO functions powerpc is a bit special for VDSO as well as system calls in the way that it requires setting CR SO bit which cannot be done in C. Therefore, entry/exit needs to be performed in ASM. Implementing __arch_get_vdso_data() would clobber the link register, requiring the caller to save it. As the ASM calling function already has to set a stack frame and saves the link register before calling the C vdso function, retriving the vdso data pointer there is lighter. Implement __arch_vdso_capable() and always return true. Provide vdso_shift_ns(), as the generic x >> s gives the following bad result: 18: 35 25 ff e0 addic. r9,r5,-32 1c: 41 80 00 10 blt 2c <shift+0x14> 20: 7c 64 4c 30 srw r4,r3,r9 24: 38 60 00 00 li r3,0 ... 2c: 54 69 08 3c rlwinm r9,r3,1,0,30 30: 21 45 00 1f subfic r10,r5,31 34: 7c 84 2c 30 srw r4,r4,r5 38: 7d 29 50 30 slw r9,r9,r10 3c: 7c 63 2c 30 srw r3,r3,r5 40: 7d 24 23 78 or r4,r9,r4 In our case the shift is always <= 32. In addition, the upper 32 bits of the result are likely nul. Lets GCC know it, it also optimises the following calculations. With the patch, we get: 0: 21 25 00 20 subfic r9,r5,32 4: 7c 69 48 30 slw r9,r3,r9 8: 7c 84 2c 30 srw r4,r4,r5 c: 7d 24 23 78 or r4,r9,r4 10: 7c 63 2c 30 srw r3,r3,r5 Signed-off-by:
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Michael Ellerman authored
Currently we use ifdef __powerpc64__ in barrier.h to decide if we should use lwsync or eieio for SMPWMB which is then used by __smp_wmb(). That means when we are building the compat VDSO we will use eieio, because it's 32-bit code, even though we're building a 64-bit kernel for a 64-bit CPU. Although eieio should work, it would be cleaner if we always used the same barrier, even for the 32-bit VDSO. So change the ifdef to CONFIG_PPC64, so that the selection is made based on the bitness of the kernel we're building for, not the current compilation unit. Signed-off-by:
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Michael Ellerman authored
When we're building the compat VDSO we are building 32-bit code but in the context of a 64-bit kernel configuration. To make this work we need to be careful in some places when using ifdefs to differentiate between CONFIG_PPC64 and __powerpc64__. CONFIG_PPC64 indicates the kernel we're building is 64-bit, but it doesn't tell us that we're currently building 64-bit code - we could be building 32-bit code for the compat VDSO. On the other hand __powerpc64__ tells us that we are currently building 64-bit code (and therefore we must also be building a 64-bit kernel). In the case of get_tb() we want to use the 32-bit code sequence regardless of whether the kernel we're building for is 64-bit or 32-bit, what matters is the word size of the current object. So we need to check __powerpc64__ to decide if we use mftb() or the mftbu()/mftb() sequence. For mftb() the logic for CPU_FTR_CELL_TB_BUG only makes sense if we're building 64-bit code, so guard that with a __powerpc64__ check. Signed-off-by:
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Christophe Leroy authored
In order to easily use get_tb() from C VDSO, move timebase functions into a new header named asm/vdso/timebase.h Signed-off-by:
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Christophe Leroy authored
cpu_relax() need to be in asm/vdso/processor.h to be used by the C VDSO generic library. Move it there. Signed-off-by:
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Christophe Leroy authored
In order to build VDSO32 for PPC64, we need to have CPU_FTRS_POSSIBLE and CPU_FTRS_ALWAYS independant of whether we are building the 32 bits VDSO or the 64 bits VDSO. Use #ifdef CONFIG_PPC64 instead of #ifdef __powerpc64__ Signed-off-by:
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Michael Ellerman authored
Update the NUMA Kconfig description to match other architectures, and add some help text. Shamelessly borrowed from x86/arm64. Signed-off-by:
Randy Dunlap <rdunlap@infradead.org> Link: https://lore.kernel.org/r/20201124120547.1940635-3-mpe@ellerman.id.au
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Michael Ellerman authored
Our NUMA option is default y for pseries, but not powernv. The bulk of powernv systems are NUMA, so make NUMA default y for powernv also. Signed-off-by:
Srikar Dronamraju <srikar@linux.vnet.ibm.com> Link: https://lore.kernel.org/r/20201124120547.1940635-2-mpe@ellerman.id.au
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Michael Ellerman authored
Our Kconfig allows NUMA to be enabled without SMP, but none of our defconfigs use that combination. This means it can easily be broken inadvertently by code changes, which has happened recently. Although it's theoretically possible to have a machine with a single CPU and multiple memory nodes, I can't think of any real systems where that's the case. Even so if such a system exists, it can just run an SMP kernel anyway. So to avoid the need to add extra #ifdefs and/or build breaks, make NUMA depend on SMP. Reported-by:
kernel test robot <lkp@intel.com> Reported-by:
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Christophe Leroy authored
ioreadXX()/ioreadXXbe() accessors are equivalent to ppc in_leXX()/in_be16() accessors but they are not inlined. Since commit 0eb57368 ("powerpc/kerenl: Enable EEH for IO accessors"), the 'le' versions are equivalent to the ones defined in asm-generic/io.h, allthough the ones there are inlined. Include asm-generic/io.h to get them. Keep ppc versions of the 'be' ones as they are optimised, but make them inline in ppc io.h. This reduces the size of ppc64e_defconfig build by 3 kbytes: text data bss dec hex filename 10160733 4343422 562972 15067127 e5e7f7 vmlinux.before 10159239 4341590 562972 15063801 e5daf9 vmlinux.after A typical function using ioread and iowrite before the change: c00000000066a3c4 <.ata_bmdma_stop>: c00000000066a3c4: 7c 08 02 a6 mflr r0 c00000000066a3c8: fb c1 ff f0 std r30,-16(r1) c00000000066a3cc: f8 01 00 10 std r0,16(r1) c00000000066a3d0: fb e1 ff f8 std r31,-8(r1) c00000000066a3d4: f8 21 ff 81 stdu r1,-128(r1) c00000000066a3d8: eb e3 00 00 ld r31,0(r3) c00000000066a3dc: eb df 00 98 ld r30,152(r31) c00000000066a3e0: 7f c3 f3 78 mr r3,r30 c00000000066a3e4: 4b 9b 6f 7d bl c000000000021360 <.ioread8> c00000000066a3e8: 60 00 00 00 nop c00000000066a3ec: 7f c4 f3 78 mr r4,r30 c00000000066a3f0: 54 63 06 3c rlwinm r3,r3,0,24,30 c00000000066a3f4: 4b 9b 70 4d bl c000000000021440 <.iowrite8> c00000000066a3f8: 60 00 00 00 nop c00000000066a3fc: 7f e3 fb 78 mr r3,r31 c00000000066a400: 38 21 00 80 addi r1,r1,128 c00000000066a404: e8 01 00 10 ld r0,16(r1) c00000000066a408: eb c1 ff f0 ld r30,-16(r1) c00000000066a40c: 7c 08 03 a6 mtlr r0 c00000000066a410: eb e1 ff f8 ld r31,-8(r1) c00000000066a414: 4b ff ff 8c b c00000000066a3a0 <.ata_sff_dma_pause> The same function with this patch: c000000000669cb4 <.ata_bmdma_stop>: c000000000669cb4: e8 63 00 00 ld r3,0(r3) c000000000669cb8: e9 43 00 98 ld r10,152(r3) c000000000669cbc: 7c 00 04 ac hwsync c000000000669cc0: 89 2a 00 00 lbz r9,0(r10) c000000000669cc4: 0c 09 00 00 twi 0,r9,0 c000000000669cc8: 4c 00 01 2c isync c000000000669ccc: 55 29 06 3c rlwinm r9,r9,0,24,30 c000000000669cd0: 7c 00 04 ac hwsync c000000000669cd4: 99 2a 00 00 stb r9,0(r10) c000000000669cd8: a1 4d 06 f0 lhz r10,1776(r13) c000000000669cdc: 2c 2a 00 00 cmpdi r10,0 c000000000669ce0: 41 c2 00 08 beq- c000000000669ce8 <.ata_bmdma_stop+0x34> c000000000669ce4: b1 4d 06 f2 sth r10,1778(r13) c000000000669ce8: 4b ff ff a8 b c000000000669c90 <.ata_sff_dma_pause> Signed-off-by:
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Athira Rajeev authored
On systems without any specific PMU driver support registered, running 'perf record' with —intr-regs will crash ( perf record -I <workload> ). The relevant portion from crash logs and Call Trace: Unable to handle kernel paging request for data at address 0x00000068 Faulting instruction address: 0xc00000000013eb18 Oops: Kernel access of bad area, sig: 11 [#1] CPU: 2 PID: 13435 Comm: kill Kdump: loaded Not tainted 4.18.0-193.el8.ppc64le #1 NIP: c00000000013eb18 LR: c000000000139f2c CTR: c000000000393d80 REGS: c0000004a07ab4f0 TRAP: 0300 Not tainted (4.18.0-193.el8.ppc64le) NIP [c00000000013eb18] is_sier_available+0x18/0x30 LR [c000000000139f2c] perf_reg_value+0x6c/0xb0 Call Trace: [c0000004a07ab770] [c0000004a07ab7c8] 0xc0000004a07ab7c8 (unreliable) [c0000004a07ab7a0] [c0000000003aa77c] perf_output_sample+0x60c/0xac0 [c0000004a07ab840] [c0000000003ab3f0] perf_event_output_forward+0x70/0xb0 [c0000004a07ab8c0] [c00000000039e208] __perf_event_overflow+0x88/0x1a0 [c0000004a07ab910] [c00000000039e42c] perf_swevent_hrtimer+0x10c/0x1d0 [c0000004a07abc50] [c000000000228b9c] __hrtimer_run_queues+0x17c/0x480 [c0000004a07abcf0] [c00000000022aaf4] hrtimer_interrupt+0x144/0x520 [c0000004a07abdd0] [c00000000002a864] timer_interrupt+0x104/0x2f0 [c0000004a07abe30] [c0000000000091c4] decrementer_common+0x114/0x120 When perf record session is started with "-I" option, capturing registers on each sample calls is_sier_available() to check for the SIER (Sample Instruction Event Register) availability in the platform. This function in core-book3s accesses 'ppmu->flags'. If a platform specific PMU driver is not registered, ppmu is set to NULL and accessing its members results in a crash. Fix the crash by returning false in is_sier_available() if ppmu is not set. Fixes: 333804dc ("powerpc/perf: Update perf_regs structure to include SIER") Reported-by:
Sachin Sant <sachinp@linux.vnet.ibm.com> Signed-off-by:
Athira Rajeev <atrajeev@linux.vnet.ibm.com> Signed-off-by:
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Alan Modra authored
Use bcl 20,31,0f rather than plain bl to avoid unbalancing the link stack. Update the code to use REL16 relocs, available for ppc64 in 2009 (and ppc32 in 2005). Signed-off-by:
Alan Modra <amodra@gmail.com> [mpe: Incorporate more detail into the change log] Signed-off-by:
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- 26 Nov, 2020 7 commits
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Bill Wendling authored
The clang toolchain treats inline assembly a bit differently than straight assembly code. In particular, inline assembly doesn't have the complete context available to resolve expressions. This is intentional to avoid divergence in the resulting assembly code. We can work around this issue by borrowing a workaround done for ARM, i.e. not directly testing the labels themselves, but by moving the current output pointer by a value that should always be zero. If this value is not null, then we will trigger a backward move, which is explicitly forbidden. Signed-off-by:
Bill Wendling <morbo@google.com> [mpe: Put it in a macro and only do the workaround for clang] Signed-off-by:
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Bill Wendling authored
The gcc compiler may not be available if CC is clang. Signed-off-by:
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Bill Wendling authored
The "-z notext" flag disables reporting an error if DT_TEXTREL is set. ld.lld: error: can't create dynamic relocation R_PPC64_ADDR64 against symbol: _start in readonly segment; recompile object files with -fPIC or pass '-Wl,-z,notext' to allow text relocations in the output >>> defined in >>> referenced by crt0.o:(.text+0x8) in archive arch/powerpc/boot/wrapper.a The BFD linker disables this by default (though it's configurable in current versions). LLD enables this by default. So we add the flag to keep LLD from emitting the error. Signed-off-by: -
Bill Wendling authored
Normally all read-only sections precede SHF_WRITE sections. .dynamic and .got have the SHF_WRITE flag; .dynamic probably because of DT_DEBUG. LLD emits an error when this happens, so use "-z rodynamic" to mark .dynamic as read-only. Signed-off-by:
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Bill Wendling authored
Both .dynamic and .got are RELRO sections and should be placed together, and LLD emits an error: ld.lld: error: section: .got is not contiguous with other relro sections Place them together to avoid this. Signed-off-by:
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Oleg Nesterov authored
The commit a8a4b03a ("powerpc: Hard wire PT_SOFTE value to 1 in ptrace & signals") changed ptrace_get_reg(PT_SOFTE) to report 0x1, but PTRACE_GETREGS still copies pt_regs->softe as is. This is not consistent and this breaks the user-regs-peekpoke test from https://sourceware.org/systemtap/wiki/utrace/tests/Reported-by:
Jan Kratochvil <jan.kratochvil@redhat.com> Signed-off-by:
Oleg Nesterov <oleg@redhat.com> Signed-off-by:
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Oleg Nesterov authored
gpr_get() does membuf_write() twice to override pt_regs->msr in between. We can call membuf_write() once and change ->msr in the kernel buffer, this simplifies the code and the next fix. The patch adds a new simple helper, membuf_at(offs), it returns the new membuf which can be safely used after membuf_write(). Signed-off-by:
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- 25 Nov, 2020 1 commit
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Michael Ellerman authored
Merge our fixes branch, in particular to bring in the changes for the entry/uaccess flush.
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- 23 Nov, 2020 2 commits
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Stephen Rothwell authored
Using DECLARE_STATIC_KEY_FALSE needs linux/jump_table.h. Otherwise the build fails with eg: arch/powerpc/include/asm/book3s/64/kup-radix.h:66:1: warning: data definition has no type or storage class 66 | DECLARE_STATIC_KEY_FALSE(uaccess_flush_key); Fixes: 9a32a7e7 ("powerpc/64s: flush L1D after user accesses") Signed-off-by:Stephen Rothwell <sfr@canb.auug.org.au> [mpe: Massage change log] Signed-off-by:
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Michael Ellerman authored
From Daniel's cover letter: IBM Power9 processors can speculatively operate on data in the L1 cache before it has been completely validated, via a way-prediction mechanism. It is not possible for an attacker to determine the contents of impermissible memory using this method, since these systems implement a combination of hardware and software security measures to prevent scenarios where protected data could be leaked. However these measures don't address the scenario where an attacker induces the operating system to speculatively execute instructions using data that the attacker controls. This can be used for example to speculatively bypass "kernel user access prevention" techniques, as discovered by Anthony Steinhauser of Google's Safeside Project. This is not an attack by itself, but there is a possibility it could be used in conjunction with side-channels or other weaknesses in the privileged code to construct an attack. This issue can be mitigated by flushing the L1 cache between privilege boundaries of concern. This patch series flushes the L1 cache on kernel entry (patch 2) and after the kernel performs any user accesses (patch 3). It also adds a self-test and performs some related cleanups.
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- 19 Nov, 2020 15 commits
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Daniel Axtens authored
pseries|pnv_setup_rfi_flush already does the count cache flush setup, and we just added entry and uaccess flushes. So the name is not very accurate any more. In both platforms we then also immediately setup the STF flush. Rename them to _setup_security_mitigations and fold the STF flush in. Signed-off-by:
Daniel Axtens <dja@axtens.net> Signed-off-by:
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Daniel Axtens authored
For simplicity in backporting, the original entry_flush test contained a lot of duplicated code from the rfi_flush test. De-duplicate that code. Signed-off-by:
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Daniel Axtens authored
Add a test modelled on the RFI flush test which counts the number of L1D misses doing a simple syscall with the entry flush on and off. For simplicity of backporting, this test duplicates a lot of code from rfi_flush. We clean that up in the next patch. Signed-off-by:
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Michael Ellerman authored
In kup.h we currently include kup-radix.h for all 64-bit builds, which includes Book3S and Book3E. The latter doesn't make sense, Book3E never uses the Radix MMU. This has worked up until now, but almost by accident, and the recent uaccess flush changes introduced a build breakage on Book3E because of the bad structure of the code. So disentangle things so that we only use kup-radix.h for Book3S. This requires some more stubs in kup.h and fixing an include in syscall_64.c. Signed-off-by: -
Nicholas Piggin authored
IBM Power9 processors can speculatively operate on data in the L1 cache before it has been completely validated, via a way-prediction mechanism. It is not possible for an attacker to determine the contents of impermissible memory using this method, since these systems implement a combination of hardware and software security measures to prevent scenarios where protected data could be leaked. However these measures don't address the scenario where an attacker induces the operating system to speculatively execute instructions using data that the attacker controls. This can be used for example to speculatively bypass "kernel user access prevention" techniques, as discovered by Anthony Steinhauser of Google's Safeside Project. This is not an attack by itself, but there is a possibility it could be used in conjunction with side-channels or other weaknesses in the privileged code to construct an attack. This issue can be mitigated by flushing the L1 cache between privilege boundaries of concern. This patch flushes the L1 cache after user accesses. This is part of the fix for CVE-2020-4788. Signed-off-by:
Nicholas Piggin <npiggin@gmail.com> Signed-off-by:
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Nicholas Piggin authored
IBM Power9 processors can speculatively operate on data in the L1 cache before it has been completely validated, via a way-prediction mechanism. It is not possible for an attacker to determine the contents of impermissible memory using this method, since these systems implement a combination of hardware and software security measures to prevent scenarios where protected data could be leaked. However these measures don't address the scenario where an attacker induces the operating system to speculatively execute instructions using data that the attacker controls. This can be used for example to speculatively bypass "kernel user access prevention" techniques, as discovered by Anthony Steinhauser of Google's Safeside Project. This is not an attack by itself, but there is a possibility it could be used in conjunction with side-channels or other weaknesses in the privileged code to construct an attack. This issue can be mitigated by flushing the L1 cache between privilege boundaries of concern. This patch flushes the L1 cache on kernel entry. This is part of the fix for CVE-2020-4788. Signed-off-by:
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Russell Currey authored
We are about to add an entry flush. The rfi (exit) flush test measures the number of L1D flushes over a syscall with the RFI flush enabled and disabled. But if the entry flush is also enabled, the effect of enabling and disabling the RFI flush is masked. If there is a debugfs entry for the entry flush, disable it during the RFI flush and restore it later. Reported-by:
Spoorthy S <spoorts2@in.ibm.com> Signed-off-by:
Russell Currey <ruscur@russell.cc> Signed-off-by:
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David Hildenbrand authored
Let's use alloc_contig_pages() for allocating memory and remove the linear mapping manually via arch_remove_linear_mapping(). Mark all pages PG_offline, such that they will definitely not get touched - e.g., when hibernating. When freeing memory, try to revert what we did. The original idea was discussed in: https://lkml.kernel.org/r/48340e96-7e6b-736f-9e23-d3111b915b6e@redhat.com This is similar to CONFIG_DEBUG_PAGEALLOC handling on other architectures, whereby only single pages are unmapped from the linear mapping. Let's mimic what memory hot(un)plug would do with the linear mapping. We now need MEMORY_HOTPLUG and CONTIG_ALLOC as dependencies. Add a TODO that we want to use __GFP_ZERO for clearing once alloc_contig_pages() understands that. Tested with in QEMU/TCG with 10 GiB of main memory: [root@localhost ~]# echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 105.903043][ T1080] memtrace: Allocated trace memory on node 0 at 0x0000000080000000 [root@localhost ~]# echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 145.042493][ T1080] radix-mmu: Mapped 0x0000000080000000-0x00000000c0000000 with 64.0 KiB pages [ 145.049019][ T1080] memtrace: Freed trace memory back on node 0 [ 145.333960][ T1080] memtrace: Allocated trace memory on node 0 at 0x0000000080000000 [root@localhost ~]# echo 0x80000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 213.606916][ T1080] radix-mmu: Mapped 0x0000000080000000-0x00000000c0000000 with 64.0 KiB pages [ 213.613855][ T1080] memtrace: Freed trace memory back on node 0 [ 214.185094][ T1080] memtrace: Allocated trace memory on node 0 at 0x0000000080000000 [root@localhost ~]# echo 0x100000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 234.874872][ T1080] radix-mmu: Mapped 0x0000000080000000-0x0000000100000000 with 64.0 KiB pages [ 234.886974][ T1080] memtrace: Freed trace memory back on node 0 [ 234.890153][ T1080] memtrace: Failed to allocate trace memory on node 0 [root@localhost ~]# echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 259.490196][ T1080] memtrace: Allocated trace memory on node 0 at 0x0000000080000000 I also made sure allocated memory is properly zeroed. Note 1: We currently won't be allocating from ZONE_MOVABLE - because our pages are not movable. However, as we don't run with any memory hot(un)plug mechanism around, we could make an exception to increase the chance of allocations succeeding. Note 2: PG_reserved isn't sufficient. E.g., kernel_page_present() used along PG_reserved in hibernation code will always return "true" on powerpc, resulting in the pages getting touched. It's too generic - e.g., indicates boot allocations. Note 3: For now, we keep using memory_block_size_bytes() as minimum granularity. Suggested-by:
Michal Hocko <mhocko@kernel.org> Signed-off-by:
David Hildenbrand <david@redhat.com> Reviewed-by:
Oscar Salvador <osalvador@suse.de> Signed-off-by:
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David Hildenbrand authored
Let's revert what we did in case something goes wrong and we return an error - as already done on arm64 and s390x. Signed-off-by:
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David Hildenbrand authored
The single caller (arch_remove_linear_mapping()) prints a proper warning when this function fails. No need to eventually crash the kernel - let's drop this WARN_ON. Suggested-by:
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David Hildenbrand authored
Let's print a warning similar to in arch_add_linear_mapping() instead of WARN_ON_ONCE() and eventually crashing the kernel. Signed-off-by:
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David Hildenbrand authored
This code currently relies on mem_hotplug_begin()/mem_hotplug_done() - create_section_mapping()/remove_section_mapping() implementations cannot tollerate getting called concurrently. Let's prepare for callers (memtrace) not holding any such locks (and don't force them to mess with memory hotplug locks). Other parts in these functions don't seem to rely on external locking. Signed-off-by:
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David Hildenbrand authored
We want to stop abusing memory hotplug infrastructure in memtrace code to perform allocations and remove the linear mapping. Instead we will use alloc_contig_pages() and remove the linear mapping manually. Let's factor out creating/removing the linear mapping into arch_create_linear_mapping() / arch_remove_linear_mapping() - so in the future, we might be able to have whole arch_add_memory() / arch_remove_memory() be implemented in common code. Signed-off-by:
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David Hildenbrand authored
It's very easy to crash the kernel right now by simply trying to enable memtrace concurrently, hammering on the "enable" interface loop.sh: #!/bin/bash dmesg --console-off while true; do echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable done [root@localhost ~]# loop.sh & [root@localhost ~]# loop.sh & Resulting quickly in a kernel crash. Let's properly protect using a mutex. Fixes: 9d5171a8 ("powerpc/powernv: Enable removal of memory for in memory tracing") Cc: stable@vger.kernel.org# v4.14+ Signed-off-by: -
David Hildenbrand authored
We currently leak kernel memory to user space, because memory offlining doesn't do any implicit clearing of memory and we are missing explicit clearing of memory. Let's keep it simple and clear pages before removing the linear mapping. Reproduced in QEMU/TCG with 10 GiB of main memory: [root@localhost ~]# dd obs=9G if=/dev/urandom of=/dev/null [... wait until "free -m" used counter no longer changes and cancel] 19665802+0 records in 1+0 records out 9663676416 bytes (9.7 GB, 9.0 GiB) copied, 135.548 s, 71.3 MB/s [root@localhost ~]# cat /sys/devices/system/memory/block_size_bytes 40000000 [root@localhost ~]# echo 0x40000000 > /sys/kernel/debug/powerpc/memtrace/enable [ 402.978663][ T1086] page:000000001bc4bc74 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x24900 [ 402.980063][ T1086] flags: 0x7ffff000001000(reserved) [ 402.980415][ T1086] raw: 007ffff000001000 c00c000000924008 c00c000000924008 0000000000000000 [ 402.980627][ T1086] raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000 [ 402.980845][ T1086] page dumped because: unmovable page [ 402.989608][ T1086] Offlined Pages 16384 [ 403.324155][ T1086] memtrace: Allocated trace memory on node 0 at 0x0000000200000000 Before this patch: [root@localhost ~]# hexdump -C /sys/kernel/debug/powerpc/memtrace/00000000/trace | head 00000000 c8 25 72 51 4d 26 36 c5 5c c2 56 15 d5 1a cd 10 |.%rQM&6.\.V.....| 00000010 19 b9 50 b2 cb e3 60 b8 ec 0a f3 ec 4b 3c 39 f0 |..P...`.....K<9.|$ 00000020 4e 5a 4c cf bd 26 19 ff 37 79 13 67 24 b7 b8 57 |NZL..&..7y.g$..W|$ 00000030 98 3e f5 be 6f 14 6a bd a4 52 bc 6e e9 e0 c1 5d |.>..o.j..R.n...]|$ 00000040 76 b3 ae b5 88 d7 da e3 64 23 85 2c 10 88 07 b6 |v.......d#.,....|$ 00000050 9a d8 91 de f7 50 27 69 2e 64 9c 6f d3 19 45 79 |.....P'i.d.o..Ey|$ 00000060 6a 6f 8a 61 71 19 1f c7 f1 df 28 26 ca 0f 84 55 |jo.aq.....(&...U|$ 00000070 01 3f be e4 e2 e1 da ff 7b 8c 8e 32 37 b4 24 53 |.?......{..27.$S|$ 00000080 1b 70 30 45 56 e6 8c c4 0e b5 4c fb 9f dd 88 06 |.p0EV.....L.....|$ 00000090 ef c4 18 79 f1 60 b1 5c 79 59 4d f4 36 d7 4a 5c |...y.`.\yYM.6.J\|$ After this patch: [root@localhost ~]# hexdump -C /sys/kernel/debug/powerpc/memtrace/00000000/trace | head 00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 40000000 Fixes: 9d5171a8 ("powerpc/powernv: Enable removal of memory for in memory tracing") Cc: stable@vger.kernel.org # v4.14+ Reported-by:
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