diff options
Diffstat (limited to 'arch/riscv/kernel/patch.c')
-rw-r--r-- | arch/riscv/kernel/patch.c | 172 |
1 files changed, 156 insertions, 16 deletions
diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c index 765004b60513..37e87fdcf6a0 100644 --- a/arch/riscv/kernel/patch.c +++ b/arch/riscv/kernel/patch.c @@ -6,20 +6,34 @@ #include <linux/spinlock.h> #include <linux/mm.h> #include <linux/memory.h> +#include <linux/string.h> #include <linux/uaccess.h> #include <linux/stop_machine.h> #include <asm/kprobes.h> #include <asm/cacheflush.h> #include <asm/fixmap.h> +#include <asm/ftrace.h> #include <asm/patch.h> +#include <asm/sections.h> struct patch_insn { void *addr; - u32 insn; + u32 *insns; + int ninsns; atomic_t cpu_count; }; +int riscv_patch_in_stop_machine = false; + #ifdef CONFIG_MMU + +static inline bool is_kernel_exittext(uintptr_t addr) +{ + return system_state < SYSTEM_RUNNING && + addr >= (uintptr_t)__exittext_begin && + addr < (uintptr_t)__exittext_end; +} + /* * The fix_to_virt(, idx) needs a const value (not a dynamic variable of * reg-a0) or BUILD_BUG_ON failed with "idx >= __end_of_fixed_addresses". @@ -30,7 +44,7 @@ static __always_inline void *patch_map(void *addr, const unsigned int fixmap) uintptr_t uintaddr = (uintptr_t) addr; struct page *page; - if (core_kernel_text(uintaddr)) + if (core_kernel_text(uintaddr) || is_kernel_exittext(uintaddr)) page = phys_to_page(__pa_symbol(addr)); else if (IS_ENABLED(CONFIG_STRICT_MODULE_RWX)) page = vmalloc_to_page(addr); @@ -49,21 +63,67 @@ static void patch_unmap(int fixmap) } NOKPROBE_SYMBOL(patch_unmap); -static int patch_insn_write(void *addr, const void *insn, size_t len) +static int __patch_insn_set(void *addr, u8 c, size_t len) +{ + void *waddr = addr; + bool across_pages = (((uintptr_t)addr & ~PAGE_MASK) + len) > PAGE_SIZE; + + /* + * Only two pages can be mapped at a time for writing. + */ + if (len + offset_in_page(addr) > 2 * PAGE_SIZE) + return -EINVAL; + /* + * Before reaching here, it was expected to lock the text_mutex + * already, so we don't need to give another lock here and could + * ensure that it was safe between each cores. + */ + lockdep_assert_held(&text_mutex); + + if (across_pages) + patch_map(addr + PAGE_SIZE, FIX_TEXT_POKE1); + + waddr = patch_map(addr, FIX_TEXT_POKE0); + + memset(waddr, c, len); + + patch_unmap(FIX_TEXT_POKE0); + + if (across_pages) + patch_unmap(FIX_TEXT_POKE1); + + return 0; +} +NOKPROBE_SYMBOL(__patch_insn_set); + +static int __patch_insn_write(void *addr, const void *insn, size_t len) { void *waddr = addr; bool across_pages = (((uintptr_t) addr & ~PAGE_MASK) + len) > PAGE_SIZE; int ret; /* + * Only two pages can be mapped at a time for writing. + */ + if (len + offset_in_page(addr) > 2 * PAGE_SIZE) + return -EINVAL; + + /* * Before reaching here, it was expected to lock the text_mutex * already, so we don't need to give another lock here and could * ensure that it was safe between each cores. + * + * We're currently using stop_machine() for ftrace & kprobes, and while + * that ensures text_mutex is held before installing the mappings it + * does not ensure text_mutex is held by the calling thread. That's + * safe but triggers a lockdep failure, so just elide it for that + * specific case. */ - lockdep_assert_held(&text_mutex); + if (!riscv_patch_in_stop_machine) + lockdep_assert_held(&text_mutex); if (across_pages) - patch_map(addr + len, FIX_TEXT_POKE1); + patch_map(addr + PAGE_SIZE, FIX_TEXT_POKE1); waddr = patch_map(addr, FIX_TEXT_POKE0); @@ -76,15 +136,79 @@ static int patch_insn_write(void *addr, const void *insn, size_t len) return ret; } -NOKPROBE_SYMBOL(patch_insn_write); +NOKPROBE_SYMBOL(__patch_insn_write); #else -static int patch_insn_write(void *addr, const void *insn, size_t len) +static int __patch_insn_set(void *addr, u8 c, size_t len) +{ + memset(addr, c, len); + + return 0; +} +NOKPROBE_SYMBOL(__patch_insn_set); + +static int __patch_insn_write(void *addr, const void *insn, size_t len) { return copy_to_kernel_nofault(addr, insn, len); } -NOKPROBE_SYMBOL(patch_insn_write); +NOKPROBE_SYMBOL(__patch_insn_write); #endif /* CONFIG_MMU */ +static int patch_insn_set(void *addr, u8 c, size_t len) +{ + size_t patched = 0; + size_t size; + int ret = 0; + + /* + * __patch_insn_set() can only work on 2 pages at a time so call it in a + * loop with len <= 2 * PAGE_SIZE. + */ + while (patched < len && !ret) { + size = min_t(size_t, PAGE_SIZE * 2 - offset_in_page(addr + patched), len - patched); + ret = __patch_insn_set(addr + patched, c, size); + + patched += size; + } + + return ret; +} +NOKPROBE_SYMBOL(patch_insn_set); + +int patch_text_set_nosync(void *addr, u8 c, size_t len) +{ + u32 *tp = addr; + int ret; + + ret = patch_insn_set(tp, c, len); + + if (!ret) + flush_icache_range((uintptr_t)tp, (uintptr_t)tp + len); + + return ret; +} +NOKPROBE_SYMBOL(patch_text_set_nosync); + +static int patch_insn_write(void *addr, const void *insn, size_t len) +{ + size_t patched = 0; + size_t size; + int ret = 0; + + /* + * Copy the instructions to the destination address, two pages at a time + * because __patch_insn_write() can only handle len <= 2 * PAGE_SIZE. + */ + while (patched < len && !ret) { + size = min_t(size_t, PAGE_SIZE * 2 - offset_in_page(addr + patched), len - patched); + ret = __patch_insn_write(addr + patched, insn + patched, size); + + patched += size; + } + + return ret; +} +NOKPROBE_SYMBOL(patch_insn_write); + int patch_text_nosync(void *addr, const void *insns, size_t len) { u32 *tp = addr; @@ -102,12 +226,15 @@ NOKPROBE_SYMBOL(patch_text_nosync); static int patch_text_cb(void *data) { struct patch_insn *patch = data; - int ret = 0; + unsigned long len; + int i, ret = 0; if (atomic_inc_return(&patch->cpu_count) == num_online_cpus()) { - ret = - patch_text_nosync(patch->addr, &patch->insn, - GET_INSN_LENGTH(patch->insn)); + for (i = 0; ret == 0 && i < patch->ninsns; i++) { + len = GET_INSN_LENGTH(patch->insns[i]); + ret = patch_text_nosync(patch->addr + i * len, + &patch->insns[i], len); + } atomic_inc(&patch->cpu_count); } else { while (atomic_read(&patch->cpu_count) <= num_online_cpus()) @@ -119,15 +246,28 @@ static int patch_text_cb(void *data) } NOKPROBE_SYMBOL(patch_text_cb); -int patch_text(void *addr, u32 insn) +int patch_text(void *addr, u32 *insns, int ninsns) { + int ret; struct patch_insn patch = { .addr = addr, - .insn = insn, + .insns = insns, + .ninsns = ninsns, .cpu_count = ATOMIC_INIT(0), }; - return stop_machine_cpuslocked(patch_text_cb, - &patch, cpu_online_mask); + /* + * kprobes takes text_mutex, before calling patch_text(), but as we call + * calls stop_machine(), the lockdep assertion in patch_insn_write() + * gets confused by the context in which the lock is taken. + * Instead, ensure the lock is held before calling stop_machine(), and + * set riscv_patch_in_stop_machine to skip the check in + * patch_insn_write(). + */ + lockdep_assert_held(&text_mutex); + riscv_patch_in_stop_machine = true; + ret = stop_machine_cpuslocked(patch_text_cb, &patch, cpu_online_mask); + riscv_patch_in_stop_machine = false; + return ret; } NOKPROBE_SYMBOL(patch_text); |