Rework code-patching with STRICT_KERNEL_RWX to prepare for a later 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 <[email protected]> --- v6: * Remove the pr_warn() message from unmap_patch_area(). v5: * New to series. --- arch/powerpc/lib/code-patching.c | 35 ++++++++++++++++---------------- 1 file changed, 17 insertions(+), 18 deletions(-) diff --git a/arch/powerpc/lib/code-patching.c b/arch/powerpc/lib/code-patching.c index 8d61a7d35b89..8d0bb86125d5 100644 --- a/arch/powerpc/lib/code-patching.c +++ b/arch/powerpc/lib/code-patching.c @@ -102,6 +102,7 @@ static inline void stop_using_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); static int text_area_cpu_up(unsigned int cpu) { @@ -114,6 +115,7 @@ 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; } @@ -139,7 +141,7 @@ 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; @@ -149,17 +151,20 @@ 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; @@ -199,11 +204,9 @@ static inline int unmap_patch_area(unsigned long addr) 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 @@ -215,24 +218,20 @@ 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_addr = (u32 *)(__this_cpu_read(cpu_patching_addr) | offset_in_page(addr)); + rc = __patch_instruction(addr, instr, patch_addr); - __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 */ -- 2.32.0
