Rework code-patching with STRICT_KERNEL_RWX to prepare for the next
patch which uses a temporary mm for patching under the Book3s64 Radix
MMU. Make improvements by adding a WARN_ON when the patchsite doesn't
match after patching and return the error from __patch_instruction()
properly.
Signed-off-by: Christopher M. Riedl <c...@linux.ibm.com>
---
v5: * New to series.
---
arch/powerpc/lib/code-patching.c | 51 +++++++++++++++++---------------
1 file changed, 27 insertions(+), 24 deletions(-)
diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c
index 3122d8e4cc013..9f2eba9b70ee4 100644
--- a/arch/powerpc/lib/code-patching.c
+++ b/arch/powerpc/lib/code-patching.c
@@ -102,11 +102,12 @@ static inline void unuse_temporary_mm(struct temp_mm
*temp_mm)
}
static DEFINE_PER_CPU(struct vm_struct *, text_poke_area);
+static DEFINE_PER_CPU(unsigned long, cpu_patching_addr);
#if IS_BUILTIN(CONFIG_LKDTM)
unsigned long read_cpu_patching_addr(unsigned int cpu)
{
- return (unsigned long)(per_cpu(text_poke_area, cpu))->addr;
+ return per_cpu(cpu_patching_addr, cpu);
}
#endif
@@ -121,6 +122,7 @@ static int text_area_cpu_up(unsigned int cpu)
return -1;
}
this_cpu_write(text_poke_area, area);
+ this_cpu_write(cpu_patching_addr, (unsigned long)area->addr);
return 0;
}
@@ -146,7 +148,7 @@ void __init poking_init(void)
/*
* This can be called for kernel text or a module.
*/
-static int map_patch_area(void *addr, unsigned long text_poke_addr)
+static int map_patch_area(void *addr)
{
unsigned long pfn;
int err;
@@ -156,17 +158,20 @@ static int map_patch_area(void *addr, unsigned long
text_poke_addr)
else
pfn = __pa_symbol(addr) >> PAGE_SHIFT;
- err = map_kernel_page(text_poke_addr, (pfn << PAGE_SHIFT), PAGE_KERNEL);
+ err = map_kernel_page(__this_cpu_read(cpu_patching_addr),
+ (pfn << PAGE_SHIFT), PAGE_KERNEL);
- pr_devel("Mapped addr %lx with pfn %lx:%d\n", text_poke_addr, pfn, err);
+ pr_devel("Mapped addr %lx with pfn %lx:%d\n",
+ __this_cpu_read(cpu_patching_addr), pfn, err);
if (err)
return -1;
return 0;
}
-static inline int unmap_patch_area(unsigned long addr)
+static inline int unmap_patch_area(void)
{
+ unsigned long addr = __this_cpu_read(cpu_patching_addr);
pte_t *ptep;
pmd_t *pmdp;
pud_t *pudp;
@@ -175,23 +180,23 @@ static inline int unmap_patch_area(unsigned long addr)
pgdp = pgd_offset_k(addr);
if (unlikely(!pgdp))
- return -EINVAL;
+ goto out_err;
p4dp = p4d_offset(pgdp, addr);
if (unlikely(!p4dp))
- return -EINVAL;
+ goto out_err;
pudp = pud_offset(p4dp, addr);
if (unlikely(!pudp))
- return -EINVAL;
+ goto out_err;
pmdp = pmd_offset(pudp, addr);
if (unlikely(!pmdp))
- return -EINVAL;
+ goto out_err;
ptep = pte_offset_kernel(pmdp, addr);
if (unlikely(!ptep))
- return -EINVAL;
+ goto out_err;
pr_devel("clearing mm %p, pte %p, addr %lx\n", &init_mm, ptep, addr);
@@ -202,15 +207,17 @@ static inline int unmap_patch_area(unsigned long addr)
flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
return 0;
+
+out_err:
+ pr_warn("failed to unmap %lx\n", addr);
+ return -EINVAL;
}
static int do_patch_instruction(u32 *addr, struct ppc_inst instr)
{
- int err;
+ int err, rc = 0;
u32 *patch_addr = NULL;
unsigned long flags;
- unsigned long text_poke_addr;
- unsigned long kaddr = (unsigned long)addr;
/*
* During early early boot patch_instruction is called
@@ -222,24 +229,20 @@ static int do_patch_instruction(u32 *addr, struct
ppc_inst instr)
local_irq_save(flags);
- text_poke_addr = (unsigned long)__this_cpu_read(text_poke_area)->addr;
- if (map_patch_area(addr, text_poke_addr)) {
- err = -1;
+ err = map_patch_area(addr);
+ if (err)
goto out;
- }
-
- patch_addr = (u32 *)(text_poke_addr + (kaddr & ~PAGE_MASK));
- __patch_instruction(addr, instr, patch_addr);
+ patch_addr = (u32 *)(__this_cpu_read(cpu_patching_addr) |
offset_in_page(addr));
+ rc = __patch_instruction(addr, instr, patch_addr);
- err = unmap_patch_area(text_poke_addr);
- if (err)
- pr_warn("failed to unmap %lx\n", text_poke_addr);
+ err = unmap_patch_area();
out:
local_irq_restore(flags);
+ WARN_ON(!ppc_inst_equal(ppc_inst_read(addr), instr));
- return err;
+ return rc ? rc : err;
}
#else /* !CONFIG_STRICT_KERNEL_RWX */
--
2.26.1
