arm64 fixes for 5.19-rc3:

- Revert the moving of the jump labels initialisation before
   setup_machine_fdt(). The bug was fixed in drivers/char/random.c.
 
 - Ftrace fixes: branch range check and consistent handling of PLTs.
 
 - Clean rather than invalidate FROM_DEVICE buffers at start of DMA
   transfer (safer if such buffer is mapped in user space). A cache
   invalidation is done already at the end of the transfer.
 
 - A couple of clean-ups (unexport symbol, remove unused label).
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Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 fixes from Catalin Marinas:

 - Revert the moving of the jump labels initialisation before
   setup_machine_fdt(). The bug was fixed in drivers/char/random.c.

 - Ftrace fixes: branch range check and consistent handling of PLTs.

 - Clean rather than invalidate FROM_DEVICE buffers at start of DMA
   transfer (safer if such buffer is mapped in user space). A cache
   invalidation is done already at the end of the transfer.

 - A couple of clean-ups (unexport symbol, remove unused label).

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: mm: Don't invalidate FROM_DEVICE buffers at start of DMA transfer
  arm64/cpufeature: Unexport set_cpu_feature()
  arm64: ftrace: remove redundant label
  arm64: ftrace: consistently handle PLTs.
  arm64: ftrace: fix branch range checks
  Revert "arm64: Initialize jump labels before setup_machine_fdt()"
This commit is contained in:
Linus Torvalds 2022-06-17 13:55:19 -05:00
commit ef06e68290
5 changed files with 76 additions and 86 deletions

View file

@ -3101,7 +3101,6 @@ void cpu_set_feature(unsigned int num)
WARN_ON(num >= MAX_CPU_FEATURES);
elf_hwcap |= BIT(num);
}
EXPORT_SYMBOL_GPL(cpu_set_feature);
bool cpu_have_feature(unsigned int num)
{

View file

@ -102,7 +102,6 @@ SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
* x19-x29 per the AAPCS, and we created frame records upon entry, so we need
* to restore x0-x8, x29, and x30.
*/
ftrace_common_return:
/* Restore function arguments */
ldp x0, x1, [sp]
ldp x2, x3, [sp, #S_X2]

View file

@ -77,6 +77,66 @@ static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr)
return NULL;
}
/*
* Find the address the callsite must branch to in order to reach '*addr'.
*
* Due to the limited range of 'BL' instructions, modules may be placed too far
* away to branch directly and must use a PLT.
*
* Returns true when '*addr' contains a reachable target address, or has been
* modified to contain a PLT address. Returns false otherwise.
*/
static bool ftrace_find_callable_addr(struct dyn_ftrace *rec,
struct module *mod,
unsigned long *addr)
{
unsigned long pc = rec->ip;
long offset = (long)*addr - (long)pc;
struct plt_entry *plt;
/*
* When the target is within range of the 'BL' instruction, use 'addr'
* as-is and branch to that directly.
*/
if (offset >= -SZ_128M && offset < SZ_128M)
return true;
/*
* When the target is outside of the range of a 'BL' instruction, we
* must use a PLT to reach it. We can only place PLTs for modules, and
* only when module PLT support is built-in.
*/
if (!IS_ENABLED(CONFIG_ARM64_MODULE_PLTS))
return false;
/*
* 'mod' is only set at module load time, but if we end up
* dealing with an out-of-range condition, we can assume it
* is due to a module being loaded far away from the kernel.
*
* NOTE: __module_text_address() must be called with preemption
* disabled, but we can rely on ftrace_lock to ensure that 'mod'
* retains its validity throughout the remainder of this code.
*/
if (!mod) {
preempt_disable();
mod = __module_text_address(pc);
preempt_enable();
}
if (WARN_ON(!mod))
return false;
plt = get_ftrace_plt(mod, *addr);
if (!plt) {
pr_err("ftrace: no module PLT for %ps\n", (void *)*addr);
return false;
}
*addr = (unsigned long)plt;
return true;
}
/*
* Turn on the call to ftrace_caller() in instrumented function
*/
@ -84,40 +144,9 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned long pc = rec->ip;
u32 old, new;
long offset = (long)pc - (long)addr;
if (offset < -SZ_128M || offset >= SZ_128M) {
struct module *mod;
struct plt_entry *plt;
if (!IS_ENABLED(CONFIG_ARM64_MODULE_PLTS))
return -EINVAL;
/*
* On kernels that support module PLTs, the offset between the
* branch instruction and its target may legally exceed the
* range of an ordinary relative 'bl' opcode. In this case, we
* need to branch via a trampoline in the module.
*
* NOTE: __module_text_address() must be called with preemption
* disabled, but we can rely on ftrace_lock to ensure that 'mod'
* retains its validity throughout the remainder of this code.
*/
preempt_disable();
mod = __module_text_address(pc);
preempt_enable();
if (WARN_ON(!mod))
return -EINVAL;
plt = get_ftrace_plt(mod, addr);
if (!plt) {
pr_err("ftrace: no module PLT for %ps\n", (void *)addr);
return -EINVAL;
}
addr = (unsigned long)plt;
}
if (!ftrace_find_callable_addr(rec, NULL, &addr))
return -EINVAL;
old = aarch64_insn_gen_nop();
new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);
@ -132,6 +161,11 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
unsigned long pc = rec->ip;
u32 old, new;
if (!ftrace_find_callable_addr(rec, NULL, &old_addr))
return -EINVAL;
if (!ftrace_find_callable_addr(rec, NULL, &addr))
return -EINVAL;
old = aarch64_insn_gen_branch_imm(pc, old_addr,
AARCH64_INSN_BRANCH_LINK);
new = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);
@ -181,54 +215,15 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
unsigned long addr)
{
unsigned long pc = rec->ip;
bool validate = true;
u32 old = 0, new;
long offset = (long)pc - (long)addr;
if (offset < -SZ_128M || offset >= SZ_128M) {
u32 replaced;
if (!IS_ENABLED(CONFIG_ARM64_MODULE_PLTS))
return -EINVAL;
/*
* 'mod' is only set at module load time, but if we end up
* dealing with an out-of-range condition, we can assume it
* is due to a module being loaded far away from the kernel.
*/
if (!mod) {
preempt_disable();
mod = __module_text_address(pc);
preempt_enable();
if (WARN_ON(!mod))
return -EINVAL;
}
/*
* The instruction we are about to patch may be a branch and
* link instruction that was redirected via a PLT entry. In
* this case, the normal validation will fail, but we can at
* least check that we are dealing with a branch and link
* instruction that points into the right module.
*/
if (aarch64_insn_read((void *)pc, &replaced))
return -EFAULT;
if (!aarch64_insn_is_bl(replaced) ||
!within_module(pc + aarch64_get_branch_offset(replaced),
mod))
return -EINVAL;
validate = false;
} else {
old = aarch64_insn_gen_branch_imm(pc, addr,
AARCH64_INSN_BRANCH_LINK);
}
if (!ftrace_find_callable_addr(rec, mod, &addr))
return -EINVAL;
old = aarch64_insn_gen_branch_imm(pc, addr, AARCH64_INSN_BRANCH_LINK);
new = aarch64_insn_gen_nop();
return ftrace_modify_code(pc, old, new, validate);
return ftrace_modify_code(pc, old, new, true);
}
void arch_ftrace_update_code(int command)

View file

@ -303,14 +303,13 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
early_fixmap_init();
early_ioremap_init();
/*
* Initialise the static keys early as they may be enabled by the
* cpufeature code, early parameters, and DT setup.
*/
jump_label_init();
setup_machine_fdt(__fdt_pointer);
/*
* Initialise the static keys early as they may be enabled by the
* cpufeature code and early parameters.
*/
jump_label_init();
parse_early_param();
/*

View file

@ -218,8 +218,6 @@ SYM_FUNC_ALIAS(__dma_flush_area, __pi___dma_flush_area)
*/
SYM_FUNC_START(__pi___dma_map_area)
add x1, x0, x1
cmp w2, #DMA_FROM_DEVICE
b.eq __pi_dcache_inval_poc
b __pi_dcache_clean_poc
SYM_FUNC_END(__pi___dma_map_area)
SYM_FUNC_ALIAS(__dma_map_area, __pi___dma_map_area)