AcoSail/kernel_optimize_test
8
0
Fork 0
forked from luck/tmp_suning_uos_patched
Code Pull Requests Activity

arm64: Avoid flush_icache_range() in alternatives patching code

Browse Source 
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>
This commit is contained in:
Will Deacon 2018-06-22 09:31:15 +01:00 committed by Catalin Marinas
parent 7838306f5a
commit 429388682d
3 changed files with 52 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/arm64/include/asm/alternative.h
View File

@ -28,7 +28,12 @@ typedef void (*alternative_cb_t)(struct alt_instr *alt,
__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 */ \

51
arch/arm64/kernel/alternative.c
View File

@ -122,7 +122,30 @@ static void patch_alternative(struct alt_instr *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 *alt_region, bool use_linear_alias)
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 *alt_region, bool use_linear_alias)
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_stop(void *unused)
isb();
} else {
BUG_ON(alternatives_applied);
__apply_alternatives(&region, true);
__apply_alternatives(&region, 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(&region, false);
__apply_alternatives(&region, true);
}
#endif

5
arch/arm64/kernel/module.c
View File

@ -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))