From 9721873c3c023254f04138bbb21d539b4f0f0ad6 Mon Sep 17 00:00:00 2001 From: Puranjay Mohan Date: Thu, 31 Aug 2023 13:12:27 +0000 Subject: riscv: extend patch_text_nosync() for multiple pages MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch_insn_write() function currently doesn't work for multiple pages of instructions, therefore patch_text_nosync() will fail with a page fault if called with lengths spanning multiple pages. This commit extends the patch_insn_write() function to support multiple pages by copying at max 2 pages at a time in a loop. This implementation is similar to text_poke_copy() function of x86. Signed-off-by: Puranjay Mohan Reviewed-by: Pu Lehui Reviewed-by: Björn Töpel Tested-by: Björn Töpel Acked-by: Daniel Borkmann Link: https://lore.kernel.org/r/20230831131229.497941-3-puranjay12@gmail.com Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/patch.c | 37 ++++++++++++++++++++++++++++++++----- 1 file changed, 32 insertions(+), 5 deletions(-) (limited to 'arch/riscv') diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c index 575e71d6c8ae..2c97e246f4dc 100644 --- a/arch/riscv/kernel/patch.c +++ b/arch/riscv/kernel/patch.c @@ -53,12 +53,18 @@ 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_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 @@ -74,7 +80,7 @@ static int patch_insn_write(void *addr, const void *insn, size_t len) 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); @@ -87,15 +93,36 @@ 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_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_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; -- cgit