From 072d23eef6003386d05424411522578fa75b6814 Mon Sep 17 00:00:00 2001 From: Gavin Shan Date: Tue, 28 Apr 2020 09:57:00 +1000 Subject: arm64/kernel: Fix range on invalidating dcache for boot page tables [ Upstream commit 9d2d75ede59bc1edd8561f2ee9d4702a5ea0ae30 ] Prior to commit 8eb7e28d4c642c31 ("arm64/mm: move runtime pgds to rodata"), idmap_pgd_dir, tramp_pg_dir, reserved_ttbr0, swapper_pg_dir, and init_pg_dir were contiguous at the end of the kernel image. The maintenance at the end of __create_page_tables assumed these were contiguous, and affected everything from the start of idmap_pg_dir to the end of init_pg_dir. That commit moved all but init_pg_dir into the .rodata section, with other data placed between idmap_pg_dir and init_pg_dir, but did not update the maintenance. Hence the maintenance is performed on much more data than necessary (but as the bootloader previously made this clean to the PoC there is no functional problem). As we only alter idmap_pg_dir, and init_pg_dir, we only need to perform maintenance for these. As the other dirs are in .rodata, the bootloader will have initialised them as expected and cleaned them to the PoC. The kernel will initialize them as necessary after enabling the MMU. This patch reworks the maintenance to only cover the idmap_pg_dir and init_pg_dir to avoid this unnecessary work. Signed-off-by: Gavin Shan Reviewed-by: Mark Rutland Link: https://lore.kernel.org/r/20200427235700.112220-1-gshan@redhat.com Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/kernel/vmlinux.lds.S | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm64/kernel/vmlinux.lds.S') diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index aa76f7259668..e1af25dbc57e 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -142,6 +142,7 @@ SECTIONS . = ALIGN(PAGE_SIZE); idmap_pg_dir = .; . += IDMAP_DIR_SIZE; + idmap_pg_end = .; #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 tramp_pg_dir = .; -- cgit v1.2.3 From a8f13826f9c69ca7f0c34fba5d1ff2382e38aae4 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 30 Jun 2020 10:19:21 +0200 Subject: arm64/alternatives: use subsections for replacement sequences [ Upstream commit f7b93d42945cc71e1346dd5ae07c59061d56745e ] When building very large kernels, the logic that emits replacement sequences for alternatives fails when relative branches are present in the code that is emitted into the .altinstr_replacement section and patched in at the original site and fixed up. The reason is that the linker will insert veneers if relative branches go out of range, and due to the relative distance of the .altinstr_replacement from the .text section where its branch targets usually live, veneers may be emitted at the end of the .altinstr_replacement section, with the relative branches in the sequence pointed at the veneers instead of the actual target. The alternatives patching logic will attempt to fix up the branch to point to its original target, which will be the veneer in this case, but given that the patch site is likely to be far away as well, it will be out of range and so patching will fail. There are other cases where these veneers are problematic, e.g., when the target of the branch is in .text while the patch site is in .init.text, in which case putting the replacement sequence inside .text may not help either. So let's use subsections to emit the replacement code as closely as possible to the patch site, to ensure that veneers are only likely to be emitted if they are required at the patch site as well, in which case they will be in range for the replacement sequence both before and after it is transported to the patch site. This will prevent alternative sequences in non-init code from being released from memory after boot, but this is tolerable given that the entire section is only 512 KB on an allyesconfig build (which weighs in at 500+ MB for the entire Image). Also, note that modules today carry the replacement sequences in non-init sections as well, and any of those that target init code will be emitted into init sections after this change. This fixes an early crash when booting an allyesconfig kernel on a system where any of the alternatives sequences containing relative branches are activated at boot (e.g., ARM64_HAS_PAN on TX2) Signed-off-by: Ard Biesheuvel Cc: Suzuki K Poulose Cc: James Morse Cc: Andre Przywara Cc: Dave P Martin Link: https://lore.kernel.org/r/20200630081921.13443-1-ardb@kernel.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/kernel/vmlinux.lds.S | 3 --- 1 file changed, 3 deletions(-) (limited to 'arch/arm64/kernel/vmlinux.lds.S') diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index e1af25dbc57e..8d0374ffdd2d 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -172,9 +172,6 @@ SECTIONS *(.altinstructions) __alt_instructions_end = .; } - .altinstr_replacement : { - *(.altinstr_replacement) - } . = ALIGN(PAGE_SIZE); __inittext_end = .; -- cgit v1.2.3 From 1744237ca0473a7df6ffa9b108d027ea87835653 Mon Sep 17 00:00:00 2001 From: James Morse Date: Fri, 21 Aug 2020 15:07:05 +0100 Subject: KVM: arm64: Add kvm_extable for vaxorcism code commit e9ee186bb735bfc17fa81dbc9aebf268aee5b41e upstream. KVM has a one instruction window where it will allow an SError exception to be consumed by the hypervisor without treating it as a hypervisor bug. This is used to consume asynchronous external abort that were caused by the guest. As we are about to add another location that survives unexpected exceptions, generalise this code to make it behave like the host's extable. KVM's version has to be mapped to EL2 to be accessible on nVHE systems. The SError vaxorcism code is a one instruction window, so has two entries in the extable. Because the KVM code is copied for VHE and nVHE, we end up with four entries, half of which correspond with code that isn't mapped. Cc: # 5.4.x Signed-off-by: James Morse Reviewed-by: Marc Zyngier Signed-off-by: Catalin Marinas Signed-off-by: Andre Przywara Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/vmlinux.lds.S | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch/arm64/kernel/vmlinux.lds.S') diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 8d0374ffdd2d..4f77de8ce138 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -24,6 +24,13 @@ ENTRY(_text) jiffies = jiffies_64; + +#define HYPERVISOR_EXTABLE \ + . = ALIGN(SZ_8); \ + __start___kvm_ex_table = .; \ + *(__kvm_ex_table) \ + __stop___kvm_ex_table = .; + #define HYPERVISOR_TEXT \ /* \ * Align to 4 KB so that \ @@ -39,6 +46,7 @@ jiffies = jiffies_64; __hyp_idmap_text_end = .; \ __hyp_text_start = .; \ *(.hyp.text) \ + HYPERVISOR_EXTABLE \ __hyp_text_end = .; #define IDMAP_TEXT \ -- cgit v1.2.3 From 3283bd6d19cdc38ae553367a68578741cc01e0e4 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Mon, 2 Dec 2019 16:11:07 +0000 Subject: arm64: insn: consistently handle exit text [ Upstream commit ca2ef4ffabbef25644e02a98b0f48869f8be0375 ] A kernel built with KASAN && FTRACE_WITH_REGS && !MODULES, produces a boot-time splat in the bowels of ftrace: | [ 0.000000] ftrace: allocating 32281 entries in 127 pages | [ 0.000000] ------------[ cut here ]------------ | [ 0.000000] WARNING: CPU: 0 PID: 0 at kernel/trace/ftrace.c:2019 ftrace_bug+0x27c/0x328 | [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.4.0-rc3-00008-g7f08ae53a7e3 #13 | [ 0.000000] Hardware name: linux,dummy-virt (DT) | [ 0.000000] pstate: 60000085 (nZCv daIf -PAN -UAO) | [ 0.000000] pc : ftrace_bug+0x27c/0x328 | [ 0.000000] lr : ftrace_init+0x640/0x6cc | [ 0.000000] sp : ffffa000120e7e00 | [ 0.000000] x29: ffffa000120e7e00 x28: ffff00006ac01b10 | [ 0.000000] x27: ffff00006ac898c0 x26: dfffa00000000000 | [ 0.000000] x25: ffffa000120ef290 x24: ffffa0001216df40 | [ 0.000000] x23: 000000000000018d x22: ffffa0001244c700 | [ 0.000000] x21: ffffa00011bf393c x20: ffff00006ac898c0 | [ 0.000000] x19: 00000000ffffffff x18: 0000000000001584 | [ 0.000000] x17: 0000000000001540 x16: 0000000000000007 | [ 0.000000] x15: 0000000000000000 x14: ffffa00010432770 | [ 0.000000] x13: ffff940002483519 x12: 1ffff40002483518 | [ 0.000000] x11: 1ffff40002483518 x10: ffff940002483518 | [ 0.000000] x9 : dfffa00000000000 x8 : 0000000000000001 | [ 0.000000] x7 : ffff940002483519 x6 : ffffa0001241a8c0 | [ 0.000000] x5 : ffff940002483519 x4 : ffff940002483519 | [ 0.000000] x3 : ffffa00011780870 x2 : 0000000000000001 | [ 0.000000] x1 : 1fffe0000d591318 x0 : 0000000000000000 | [ 0.000000] Call trace: | [ 0.000000] ftrace_bug+0x27c/0x328 | [ 0.000000] ftrace_init+0x640/0x6cc | [ 0.000000] start_kernel+0x27c/0x654 | [ 0.000000] random: get_random_bytes called from print_oops_end_marker+0x30/0x60 with crng_init=0 | [ 0.000000] ---[ end trace 0000000000000000 ]--- | [ 0.000000] ftrace faulted on writing | [ 0.000000] [] _GLOBAL__sub_D_65535_0___tracepoint_initcall_level+0x4/0x28 | [ 0.000000] Initializing ftrace call sites | [ 0.000000] ftrace record flags: 0 | [ 0.000000] (0) | [ 0.000000] expected tramp: ffffa000100b3344 This is due to an unfortunate combination of several factors. Building with KASAN results in the compiler generating anonymous functions to register/unregister global variables against the shadow memory. These functions are placed in .text.startup/.text.exit, and given mangled names like _GLOBAL__sub_{I,D}_65535_0_$OTHER_SYMBOL. The kernel linker script places these in .init.text and .exit.text respectively, which are both discarded at runtime as part of initmem. Building with FTRACE_WITH_REGS uses -fpatchable-function-entry=2, which also instruments KASAN's anonymous functions. When these are discarded with the rest of initmem, ftrace removes dangling references to these call sites. Building without MODULES implicitly disables STRICT_MODULE_RWX, and causes arm64's patch_map() function to treat any !core_kernel_text() symbol as something that can be modified in-place. As core_kernel_text() is only true for .text and .init.text, with the latter depending on system_state < SYSTEM_RUNNING, we'll treat .exit.text as something that can be patched in-place. However, .exit.text is mapped read-only. Hence in this configuration the ftrace init code blows up while trying to patch one of the functions generated by KASAN. We could try to filter out the call sites in .exit.text rather than initializing them, but this would be inconsistent with how we handle .init.text, and requires hooking into core bits of ftrace. The behaviour of patch_map() is also inconsistent today, so instead let's clean that up and have it consistently handle .exit.text. This patch teaches patch_map() to handle .exit.text at init time, preventing the boot-time splat above. The flow of patch_map() is reworked to make the logic clearer and minimize redundant conditionality. Fixes: 3b23e4991fb66f6d ("arm64: implement ftrace with regs") Signed-off-by: Mark Rutland Cc: Amit Daniel Kachhap Cc: Ard Biesheuvel Cc: Torsten Duwe Cc: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Sasha Levin --- arch/arm64/kernel/vmlinux.lds.S | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/arm64/kernel/vmlinux.lds.S') diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 4f77de8ce138..0bab37b1acbe 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -170,9 +170,12 @@ SECTIONS __inittext_begin = .; INIT_TEXT_SECTION(8) + + __exittext_begin = .; .exit.text : { ARM_EXIT_KEEP(EXIT_TEXT) } + __exittext_end = .; . = ALIGN(4); .altinstructions : { -- cgit v1.2.3