diff mbox series

[bpf-next,v3,2/3] riscv: implement a memset like function for text

Message ID 20230828165958.1714079-3-puranjay12@gmail.com (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series bpf, riscv: use BPF prog pack allocator in BPF JIT | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf-next-VM_Test-26 success Logs for test_verifier on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-28 success Logs for veristat
bpf/vmtest-bpf-next-VM_Test-24 success Logs for test_verifier on aarch64 with gcc
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 9 this patch: 9
netdev/cc_maintainers warning 1 maintainers not CCed: bjorn@rivosinc.com
netdev/build_clang success Errors and warnings before: 9 this patch: 9
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 9 this patch: 9
netdev/checkpatch warning CHECK: Please use a blank line after function/struct/union/enum declarations WARNING: line length of 100 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
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bpf/vmtest-bpf-next-VM_Test-15 success Logs for test_progs_no_alu32 on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-11 success Logs for test_progs on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-0 success Logs for ${{ matrix.test }} on ${{ matrix.arch }} with ${{ matrix.toolchain_full }}
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Commit Message

Puranjay Mohan Aug. 28, 2023, 4:59 p.m. UTC 
The BPF JIT needs to write invalid instructions to RX regions of memory to
invalidate removed BPF programs. This needs a function like memset() that
can work with RX memory.

Implement patch_text_set_nosync() which is similar to text_poke_set() of
x86.

Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
---
 arch/riscv/include/asm/patch.h |  1 +
 arch/riscv/kernel/patch.c      | 77 ++++++++++++++++++++++++++++++++++
 2 files changed, 78 insertions(+)

Comments

Pu Lehui Aug. 29, 2023, 2:49 a.m. UTC | #1 
On 2023/8/29 0:59, Puranjay Mohan wrote:
> The BPF JIT needs to write invalid instructions to RX regions of memory to
> invalidate removed BPF programs. This needs a function like memset() that
> can work with RX memory.
> 
> Implement patch_text_set_nosync() which is similar to text_poke_set() of
> x86.
> 
> Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
> ---
>   arch/riscv/include/asm/patch.h |  1 +
>   arch/riscv/kernel/patch.c      | 77 ++++++++++++++++++++++++++++++++++
>   2 files changed, 78 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/patch.h b/arch/riscv/include/asm/patch.h
> index 63c98833d510..e88b52d39eac 100644
> --- a/arch/riscv/include/asm/patch.h
> +++ b/arch/riscv/include/asm/patch.h
> @@ -7,6 +7,7 @@
>   #define _ASM_RISCV_PATCH_H
>   
>   int patch_text_nosync(void *addr, const void *insns, size_t len);
> +int patch_text_set_nosync(void *addr, u8 c, size_t len);
>   int patch_text(void *addr, u32 *insns, int ninsns);
>   
>   extern int riscv_patch_in_stop_machine;
> diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
> index 2c97e246f4dc..13ee7bf589a1 100644
> --- a/arch/riscv/kernel/patch.c
> +++ b/arch/riscv/kernel/patch.c
> @@ -6,6 +6,7 @@
>   #include <linux/spinlock.h>
>   #include <linux/mm.h>
>   #include <linux/memory.h>
> +#include <linux/string.h>
>   #include <linux/uaccess.h>
>   #include <linux/stop_machine.h>
>   #include <asm/kprobes.h>
> @@ -53,6 +54,39 @@ static void patch_unmap(int fixmap)
>   }
>   NOKPROBE_SYMBOL(patch_unmap);
>   
> +static int __patch_insn_set(void *addr, u8 c, size_t len)
> +{
> +	void *waddr = addr;
> +	bool across_pages = (((uintptr_t)addr & ~PAGE_MASK) + len) > PAGE_SIZE;
> +
> +	/*
> +	 * 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
> +	 * ensure that it was safe between each cores.
> +	 */
> +	lockdep_assert_held(&text_mutex);
> +
> +	if (across_pages)
> +		patch_map(addr + PAGE_SIZE, FIX_TEXT_POKE1);
> +
> +	waddr = patch_map(addr, FIX_TEXT_POKE0);
> +
> +	memset(waddr, c, len);
> +
> +	patch_unmap(FIX_TEXT_POKE0);
> +
> +	if (across_pages)
> +		patch_unmap(FIX_TEXT_POKE1);
> +
> +	return 0;
> +}
> +NOKPROBE_SYMBOL(__patch_insn_set);
> +
>   static int __patch_insn_write(void *addr, const void *insn, size_t len)
>   {
>   	void *waddr = addr;
> @@ -95,6 +129,14 @@ static int __patch_insn_write(void *addr, const void *insn, size_t len)
>   }
>   NOKPROBE_SYMBOL(__patch_insn_write);
>   #else
> +static int __patch_insn_set(void *addr, u8 c, size_t len)
> +{
> +	memset(addr, c, len);
> +
> +	return 0;
> +}
> +NOKPROBE_SYMBOL(__patch_insn_set);
> +
>   static int __patch_insn_write(void *addr, const void *insn, size_t len)
>   {
>   	return copy_to_kernel_nofault(addr, insn, len);
> @@ -102,6 +144,41 @@ static int __patch_insn_write(void *addr, const void *insn, size_t len)
>   NOKPROBE_SYMBOL(__patch_insn_write);
>   #endif /* CONFIG_MMU */
>   
> +static int patch_insn_set(void *addr, u8 c, size_t len)
> +{
> +	size_t patched = 0;
> +	size_t size;
> +	int ret = 0;
> +
> +	/*
> +	 * __patch_insn_set() can only work on 2 pages at a time so call it in a
> +	 * loop with 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_set(addr + patched, c, size);
> +
> +		patched += size;
> +	}
> +
> +	return ret;
> +}
> +NOKPROBE_SYMBOL(patch_insn_set);
> +
> +int patch_text_set_nosync(void *addr, u8 c, size_t len)
> +{
> +	u32 *tp = addr;
> +	int ret;
> +
> +	ret = patch_insn_set(tp, c, len);
> +
> +	if (!ret)
> +		flush_icache_range((uintptr_t)tp, (uintptr_t)tp + len);
> +
> +	return ret;
> +}
> +NOKPROBE_SYMBOL(patch_text_set_nosync);
> +
>   static int patch_insn_write(void *addr, const void *insn, size_t len)
>   {
>   	size_t patched = 0;

Reviewed-by: Pu Lehui <pulehui@huawei.com>
diff mbox series

Patch

diff --git a/arch/riscv/include/asm/patch.h b/arch/riscv/include/asm/patch.h
index 63c98833d510..e88b52d39eac 100644
--- a/arch/riscv/include/asm/patch.h
+++ b/arch/riscv/include/asm/patch.h
@@ -7,6 +7,7 @@ 
 #define _ASM_RISCV_PATCH_H
 
 int patch_text_nosync(void *addr, const void *insns, size_t len);
+int patch_text_set_nosync(void *addr, u8 c, size_t len);
 int patch_text(void *addr, u32 *insns, int ninsns);
 
 extern int riscv_patch_in_stop_machine;
diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
index 2c97e246f4dc..13ee7bf589a1 100644
--- a/arch/riscv/kernel/patch.c
+++ b/arch/riscv/kernel/patch.c
@@ -6,6 +6,7 @@ 
 #include <linux/spinlock.h>
 #include <linux/mm.h>
 #include <linux/memory.h>
+#include <linux/string.h>
 #include <linux/uaccess.h>
 #include <linux/stop_machine.h>
 #include <asm/kprobes.h>
@@ -53,6 +54,39 @@  static void patch_unmap(int fixmap)
 }
 NOKPROBE_SYMBOL(patch_unmap);
 
+static int __patch_insn_set(void *addr, u8 c, size_t len)
+{
+	void *waddr = addr;
+	bool across_pages = (((uintptr_t)addr & ~PAGE_MASK) + len) > PAGE_SIZE;
+
+	/*
+	 * 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
+	 * ensure that it was safe between each cores.
+	 */
+	lockdep_assert_held(&text_mutex);
+
+	if (across_pages)
+		patch_map(addr + PAGE_SIZE, FIX_TEXT_POKE1);
+
+	waddr = patch_map(addr, FIX_TEXT_POKE0);
+
+	memset(waddr, c, len);
+
+	patch_unmap(FIX_TEXT_POKE0);
+
+	if (across_pages)
+		patch_unmap(FIX_TEXT_POKE1);
+
+	return 0;
+}
+NOKPROBE_SYMBOL(__patch_insn_set);
+
 static int __patch_insn_write(void *addr, const void *insn, size_t len)
 {
 	void *waddr = addr;
@@ -95,6 +129,14 @@  static int __patch_insn_write(void *addr, const void *insn, size_t len)
 }
 NOKPROBE_SYMBOL(__patch_insn_write);
 #else
+static int __patch_insn_set(void *addr, u8 c, size_t len)
+{
+	memset(addr, c, len);
+
+	return 0;
+}
+NOKPROBE_SYMBOL(__patch_insn_set);
+
 static int __patch_insn_write(void *addr, const void *insn, size_t len)
 {
 	return copy_to_kernel_nofault(addr, insn, len);
@@ -102,6 +144,41 @@  static int __patch_insn_write(void *addr, const void *insn, size_t len)
 NOKPROBE_SYMBOL(__patch_insn_write);
 #endif /* CONFIG_MMU */
 
+static int patch_insn_set(void *addr, u8 c, size_t len)
+{
+	size_t patched = 0;
+	size_t size;
+	int ret = 0;
+
+	/*
+	 * __patch_insn_set() can only work on 2 pages at a time so call it in a
+	 * loop with 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_set(addr + patched, c, size);
+
+		patched += size;
+	}
+
+	return ret;
+}
+NOKPROBE_SYMBOL(patch_insn_set);
+
+int patch_text_set_nosync(void *addr, u8 c, size_t len)
+{
+	u32 *tp = addr;
+	int ret;
+
+	ret = patch_insn_set(tp, c, len);
+
+	if (!ret)
+		flush_icache_range((uintptr_t)tp, (uintptr_t)tp + len);
+
+	return ret;
+}
+NOKPROBE_SYMBOL(patch_text_set_nosync);
+
 static int patch_insn_write(void *addr, const void *insn, size_t len)
 {
 	size_t patched = 0;