The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From b89ddf4cca43f1269093942cf5c4e457fd45c335 Mon Sep 17 00:00:00 2001 From: Russell King russell.king@oracle.com Date: Fri, 5 Nov 2021 16:50:45 +0000 Subject: [PATCH] arm64/bpf: Remove 128MB limit for BPF JIT programs
Commit 91fc957c9b1d ("arm64/bpf: don't allocate BPF JIT programs in module memory") restricts BPF JIT program allocation to a 128MB region to ensure BPF programs are still in branching range of each other. However this restriction should not apply to the aarch64 JIT, since BPF_JMP | BPF_CALL are implemented as a 64-bit move into a register and then a BLR instruction - which has the effect of being able to call anything without proximity limitation.
The practical reason to relax this restriction on JIT memory is that 128MB of JIT memory can be quickly exhausted, especially where PAGE_SIZE is 64KB - one page is needed per program. In cases where seccomp filters are applied to multiple VMs on VM launch - such filters are classic BPF but converted to BPF - this can severely limit the number of VMs that can be launched. In a world where we support BPF JIT always on, turning off the JIT isn't always an option either.
Fixes: 91fc957c9b1d ("arm64/bpf: don't allocate BPF JIT programs in module memory") Suggested-by: Ard Biesheuvel ard.biesheuvel@linaro.org Signed-off-by: Russell King russell.king@oracle.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Tested-by: Alan Maguire alan.maguire@oracle.com Link: https://lore.kernel.org/bpf/1636131046-5982-2-git-send-email-alan.maguire@or...
diff --git a/arch/arm64/include/asm/extable.h b/arch/arm64/include/asm/extable.h index 8b300dd28def..72b0e71cc3de 100644 --- a/arch/arm64/include/asm/extable.h +++ b/arch/arm64/include/asm/extable.h @@ -33,15 +33,6 @@ do { \ (b)->data = (tmp).data; \ } while (0)
-static inline bool in_bpf_jit(struct pt_regs *regs) -{ - if (!IS_ENABLED(CONFIG_BPF_JIT)) - return false; - - return regs->pc >= BPF_JIT_REGION_START && - regs->pc < BPF_JIT_REGION_END; -} - #ifdef CONFIG_BPF_JIT bool ex_handler_bpf(const struct exception_table_entry *ex, struct pt_regs *regs); diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index 1b9a1e242612..0af70d9abede 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -44,11 +44,8 @@ #define _PAGE_OFFSET(va) (-(UL(1) << (va))) #define PAGE_OFFSET (_PAGE_OFFSET(VA_BITS)) #define KIMAGE_VADDR (MODULES_END) -#define BPF_JIT_REGION_START (_PAGE_END(VA_BITS_MIN)) -#define BPF_JIT_REGION_SIZE (SZ_128M) -#define BPF_JIT_REGION_END (BPF_JIT_REGION_START + BPF_JIT_REGION_SIZE) #define MODULES_END (MODULES_VADDR + MODULES_VSIZE) -#define MODULES_VADDR (BPF_JIT_REGION_END) +#define MODULES_VADDR (_PAGE_END(VA_BITS_MIN)) #define MODULES_VSIZE (SZ_128M) #define VMEMMAP_START (-(UL(1) << (VA_BITS - VMEMMAP_SHIFT))) #define VMEMMAP_END (VMEMMAP_START + VMEMMAP_SIZE) diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 7b21213a570f..e8986e6067a9 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -994,7 +994,7 @@ static struct break_hook bug_break_hook = { static int reserved_fault_handler(struct pt_regs *regs, unsigned int esr) { pr_err("%s generated an invalid instruction at %pS!\n", - in_bpf_jit(regs) ? "BPF JIT" : "Kernel text patching", + "Kernel text patching", (void *)instruction_pointer(regs));
/* We cannot handle this */ diff --git a/arch/arm64/mm/ptdump.c b/arch/arm64/mm/ptdump.c index 1c403536c9bb..9bc4066c5bf3 100644 --- a/arch/arm64/mm/ptdump.c +++ b/arch/arm64/mm/ptdump.c @@ -41,8 +41,6 @@ static struct addr_marker address_markers[] = { { 0 /* KASAN_SHADOW_START */, "Kasan shadow start" }, { KASAN_SHADOW_END, "Kasan shadow end" }, #endif - { BPF_JIT_REGION_START, "BPF start" }, - { BPF_JIT_REGION_END, "BPF end" }, { MODULES_VADDR, "Modules start" }, { MODULES_END, "Modules end" }, { VMALLOC_START, "vmalloc() area" }, diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 3a8a7140a9bf..86c9dc0681cc 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1141,15 +1141,12 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
u64 bpf_jit_alloc_exec_limit(void) { - return BPF_JIT_REGION_SIZE; + return VMALLOC_END - VMALLOC_START; }
void *bpf_jit_alloc_exec(unsigned long size) { - return __vmalloc_node_range(size, PAGE_SIZE, BPF_JIT_REGION_START, - BPF_JIT_REGION_END, GFP_KERNEL, - PAGE_KERNEL, 0, NUMA_NO_NODE, - __builtin_return_address(0)); + return vmalloc(size); }
void bpf_jit_free_exec(void *addr)