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riscv: extend patch_text_nosync() for multiple pages

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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 <puranjay12@gmail.com>
Reviewed-by: Pu Lehui <pulehui@huawei.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20230831131229.497941-3-puranjay12@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Puranjay Mohan 2023-08-31 13:12:27 +00:00 committed by Palmer Dabbelt
parent 20e490adea
commit 9721873c3c
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GPG key ID: 2E1319F35FBB1889
1 changed files with 32 additions and 5 deletions
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37
arch/riscv/kernel/patch.c
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@ -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;