4.17-stable review patch. If anyone has any objections, please let me know.
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From: Will Deacon will.deacon@arm.com
[ Upstream commit 429388682dc266e7a693f9c27e3aabd341d55343 ]
The implementation of flush_icache_range() includes instruction sequences which are themselves patched at runtime, so it is not safe to call from the patching framework.
This patch reworks the alternatives cache-flushing code so that it rolls its own internal D-cache maintenance using DC CIVAC before invalidating the entire I-cache after all alternatives have been applied at boot. Modules don't cause any issues, since flush_icache_range() is safe to call by the time they are loaded.
Acked-by: Mark Rutland mark.rutland@arm.com Reported-by: Rohit Khanna rokhanna@nvidia.com Cc: Alexander Van Brunt avanbrunt@nvidia.com Signed-off-by: Will Deacon will.deacon@arm.com Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/include/asm/alternative.h | 7 ++++ arch/arm64/kernel/alternative.c | 51 ++++++++++++++++++++++++++++++----- arch/arm64/kernel/module.c | 5 +-- 3 files changed, 52 insertions(+), 11 deletions(-)
--- a/arch/arm64/include/asm/alternative.h +++ b/arch/arm64/include/asm/alternative.h @@ -28,7 +28,12 @@ typedef void (*alternative_cb_t)(struct __le32 *origptr, __le32 *updptr, int nr_inst);
void __init apply_alternatives_all(void); -void apply_alternatives(void *start, size_t length); + +#ifdef CONFIG_MODULES +void apply_alternatives_module(void *start, size_t length); +#else +static inline void apply_alternatives_module(void *start, size_t length) { } +#endif
#define ALTINSTR_ENTRY(feature,cb) \ " .word 661b - .\n" /* label */ \ --- a/arch/arm64/kernel/alternative.c +++ b/arch/arm64/kernel/alternative.c @@ -122,7 +122,30 @@ static void patch_alternative(struct alt } }
-static void __apply_alternatives(void *alt_region, bool use_linear_alias) +/* + * We provide our own, private D-cache cleaning function so that we don't + * accidentally call into the cache.S code, which is patched by us at + * runtime. + */ +static void clean_dcache_range_nopatch(u64 start, u64 end) +{ + u64 cur, d_size, ctr_el0; + + ctr_el0 = read_sanitised_ftr_reg(SYS_CTR_EL0); + d_size = 4 << cpuid_feature_extract_unsigned_field(ctr_el0, + CTR_DMINLINE_SHIFT); + cur = start & ~(d_size - 1); + do { + /* + * We must clean+invalidate to the PoC in order to avoid + * Cortex-A53 errata 826319, 827319, 824069 and 819472 + * (this corresponds to ARM64_WORKAROUND_CLEAN_CACHE) + */ + asm volatile("dc civac, %0" : : "r" (cur) : "memory"); + } while (cur += d_size, cur < end); +} + +static void __apply_alternatives(void *alt_region, bool is_module) { struct alt_instr *alt; struct alt_region *region = alt_region; @@ -145,7 +168,7 @@ static void __apply_alternatives(void *a pr_info_once("patching kernel code\n");
origptr = ALT_ORIG_PTR(alt); - updptr = use_linear_alias ? lm_alias(origptr) : origptr; + updptr = is_module ? origptr : lm_alias(origptr); nr_inst = alt->orig_len / AARCH64_INSN_SIZE;
if (alt->cpufeature < ARM64_CB_PATCH) @@ -155,8 +178,20 @@ static void __apply_alternatives(void *a
alt_cb(alt, origptr, updptr, nr_inst);
- flush_icache_range((uintptr_t)origptr, - (uintptr_t)(origptr + nr_inst)); + if (!is_module) { + clean_dcache_range_nopatch((u64)origptr, + (u64)(origptr + nr_inst)); + } + } + + /* + * The core module code takes care of cache maintenance in + * flush_module_icache(). + */ + if (!is_module) { + dsb(ish); + __flush_icache_all(); + isb(); } }
@@ -178,7 +213,7 @@ static int __apply_alternatives_multi_st isb(); } else { BUG_ON(alternatives_applied); - __apply_alternatives(®ion, true); + __apply_alternatives(®ion, false); /* Barriers provided by the cache flushing */ WRITE_ONCE(alternatives_applied, 1); } @@ -192,12 +227,14 @@ void __init apply_alternatives_all(void) stop_machine(__apply_alternatives_multi_stop, NULL, cpu_online_mask); }
-void apply_alternatives(void *start, size_t length) +#ifdef CONFIG_MODULES +void apply_alternatives_module(void *start, size_t length) { struct alt_region region = { .begin = start, .end = start + length, };
- __apply_alternatives(®ion, false); + __apply_alternatives(®ion, true); } +#endif --- a/arch/arm64/kernel/module.c +++ b/arch/arm64/kernel/module.c @@ -448,9 +448,8 @@ int module_finalize(const Elf_Ehdr *hdr, const char *secstrs = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
for (s = sechdrs, se = sechdrs + hdr->e_shnum; s < se; s++) { - if (strcmp(".altinstructions", secstrs + s->sh_name) == 0) { - apply_alternatives((void *)s->sh_addr, s->sh_size); - } + if (strcmp(".altinstructions", secstrs + s->sh_name) == 0) + apply_alternatives_module((void *)s->sh_addr, s->sh_size); #ifdef CONFIG_ARM64_MODULE_PLTS if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && !strcmp(".text.ftrace_trampoline", secstrs + s->sh_name))