From ec6347bb43395cb92126788a1a5b25302543f815 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 5 Oct 2020 20:40:16 -0700 Subject: x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user, kernel}() In reaction to a proposal to introduce a memcpy_mcsafe_fast() implementation Linus points out that memcpy_mcsafe() is poorly named relative to communicating the scope of the interface. Specifically what addresses are valid to pass as source, destination, and what faults / exceptions are handled. Of particular concern is that even though x86 might be able to handle the semantics of copy_mc_to_user() with its common copy_user_generic() implementation other archs likely need / want an explicit path for this case: On Fri, May 1, 2020 at 11:28 AM Linus Torvalds wrote: > > On Thu, Apr 30, 2020 at 6:21 PM Dan Williams wrote: > > > > However now I see that copy_user_generic() works for the wrong reason. > > It works because the exception on the source address due to poison > > looks no different than a write fault on the user address to the > > caller, it's still just a short copy. So it makes copy_to_user() work > > for the wrong reason relative to the name. > > Right. > > And it won't work that way on other architectures. On x86, we have a > generic function that can take faults on either side, and we use it > for both cases (and for the "in_user" case too), but that's an > artifact of the architecture oddity. > > In fact, it's probably wrong even on x86 - because it can hide bugs - > but writing those things is painful enough that everybody prefers > having just one function. Replace a single top-level memcpy_mcsafe() with either copy_mc_to_user(), or copy_mc_to_kernel(). Introduce an x86 copy_mc_fragile() name as the rename for the low-level x86 implementation formerly named memcpy_mcsafe(). It is used as the slow / careful backend that is supplanted by a fast copy_mc_generic() in a follow-on patch. One side-effect of this reorganization is that separating copy_mc_64.S to its own file means that perf no longer needs to track dependencies for its memcpy_64.S benchmarks. [ bp: Massage a bit. ] Signed-off-by: Dan Williams Signed-off-by: Borislav Petkov Reviewed-by: Tony Luck Acked-by: Michael Ellerman Cc: Link: http://lore.kernel.org/r/CAHk-=wjSqtXAqfUJxFtWNwmguFASTgB0dz1dT3V-78Quiezqbg@mail.gmail.com Link: https://lkml.kernel.org/r/160195561680.2163339.11574962055305783722.stgit@dwillia2-desk3.amr.corp.intel.com --- tools/arch/x86/include/asm/mcsafe_test.h | 13 --- tools/arch/x86/lib/memcpy_64.S | 115 --------------------- tools/objtool/check.c | 4 +- tools/perf/bench/Build | 1 - tools/perf/bench/mem-memcpy-x86-64-lib.c | 24 ----- tools/testing/nvdimm/test/nfit.c | 49 ++++----- .../testing/selftests/powerpc/copyloops/.gitignore | 2 +- tools/testing/selftests/powerpc/copyloops/Makefile | 6 +- .../selftests/powerpc/copyloops/copy_mc_64.S | 1 + .../selftests/powerpc/copyloops/memcpy_mcsafe_64.S | 1 - 10 files changed, 32 insertions(+), 184 deletions(-) delete mode 100644 tools/arch/x86/include/asm/mcsafe_test.h delete mode 100644 tools/perf/bench/mem-memcpy-x86-64-lib.c create mode 120000 tools/testing/selftests/powerpc/copyloops/copy_mc_64.S delete mode 120000 tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S (limited to 'tools') diff --git a/tools/arch/x86/include/asm/mcsafe_test.h b/tools/arch/x86/include/asm/mcsafe_test.h deleted file mode 100644 index 2ccd588fbad4..000000000000 --- a/tools/arch/x86/include/asm/mcsafe_test.h +++ /dev/null @@ -1,13 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ -#ifndef _MCSAFE_TEST_H_ -#define _MCSAFE_TEST_H_ - -.macro MCSAFE_TEST_CTL -.endm - -.macro MCSAFE_TEST_SRC reg count target -.endm - -.macro MCSAFE_TEST_DST reg count target -.endm -#endif /* _MCSAFE_TEST_H_ */ diff --git a/tools/arch/x86/lib/memcpy_64.S b/tools/arch/x86/lib/memcpy_64.S index 45f8e1b02241..0b5b8ae56bd9 100644 --- a/tools/arch/x86/lib/memcpy_64.S +++ b/tools/arch/x86/lib/memcpy_64.S @@ -4,7 +4,6 @@ #include #include #include -#include #include #include @@ -187,117 +186,3 @@ SYM_FUNC_START(memcpy_orig) SYM_FUNC_END(memcpy_orig) .popsection - -#ifndef CONFIG_UML - -MCSAFE_TEST_CTL - -/* - * __memcpy_mcsafe - memory copy with machine check exception handling - * Note that we only catch machine checks when reading the source addresses. - * Writes to target are posted and don't generate machine checks. - */ -SYM_FUNC_START(__memcpy_mcsafe) - cmpl $8, %edx - /* Less than 8 bytes? Go to byte copy loop */ - jb .L_no_whole_words - - /* Check for bad alignment of source */ - testl $7, %esi - /* Already aligned */ - jz .L_8byte_aligned - - /* Copy one byte at a time until source is 8-byte aligned */ - movl %esi, %ecx - andl $7, %ecx - subl $8, %ecx - negl %ecx - subl %ecx, %edx -.L_read_leading_bytes: - movb (%rsi), %al - MCSAFE_TEST_SRC %rsi 1 .E_leading_bytes - MCSAFE_TEST_DST %rdi 1 .E_leading_bytes -.L_write_leading_bytes: - movb %al, (%rdi) - incq %rsi - incq %rdi - decl %ecx - jnz .L_read_leading_bytes - -.L_8byte_aligned: - movl %edx, %ecx - andl $7, %edx - shrl $3, %ecx - jz .L_no_whole_words - -.L_read_words: - movq (%rsi), %r8 - MCSAFE_TEST_SRC %rsi 8 .E_read_words - MCSAFE_TEST_DST %rdi 8 .E_write_words -.L_write_words: - movq %r8, (%rdi) - addq $8, %rsi - addq $8, %rdi - decl %ecx - jnz .L_read_words - - /* Any trailing bytes? */ -.L_no_whole_words: - andl %edx, %edx - jz .L_done_memcpy_trap - - /* Copy trailing bytes */ - movl %edx, %ecx -.L_read_trailing_bytes: - movb (%rsi), %al - MCSAFE_TEST_SRC %rsi 1 .E_trailing_bytes - MCSAFE_TEST_DST %rdi 1 .E_trailing_bytes -.L_write_trailing_bytes: - movb %al, (%rdi) - incq %rsi - incq %rdi - decl %ecx - jnz .L_read_trailing_bytes - - /* Copy successful. Return zero */ -.L_done_memcpy_trap: - xorl %eax, %eax -.L_done: - ret -SYM_FUNC_END(__memcpy_mcsafe) -EXPORT_SYMBOL_GPL(__memcpy_mcsafe) - - .section .fixup, "ax" - /* - * Return number of bytes not copied for any failure. Note that - * there is no "tail" handling since the source buffer is 8-byte - * aligned and poison is cacheline aligned. - */ -.E_read_words: - shll $3, %ecx -.E_leading_bytes: - addl %edx, %ecx -.E_trailing_bytes: - mov %ecx, %eax - jmp .L_done - - /* - * For write fault handling, given the destination is unaligned, - * we handle faults on multi-byte writes with a byte-by-byte - * copy up to the write-protected page. - */ -.E_write_words: - shll $3, %ecx - addl %edx, %ecx - movl %ecx, %edx - jmp mcsafe_handle_tail - - .previous - - _ASM_EXTABLE_FAULT(.L_read_leading_bytes, .E_leading_bytes) - _ASM_EXTABLE_FAULT(.L_read_words, .E_read_words) - _ASM_EXTABLE_FAULT(.L_read_trailing_bytes, .E_trailing_bytes) - _ASM_EXTABLE(.L_write_leading_bytes, .E_leading_bytes) - _ASM_EXTABLE(.L_write_words, .E_write_words) - _ASM_EXTABLE(.L_write_trailing_bytes, .E_trailing_bytes) -#endif diff --git a/tools/objtool/check.c b/tools/objtool/check.c index e034a8f24f46..893f021fec63 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -548,8 +548,8 @@ static const char *uaccess_safe_builtin[] = { "__ubsan_handle_shift_out_of_bounds", /* misc */ "csum_partial_copy_generic", - "__memcpy_mcsafe", - "mcsafe_handle_tail", + "copy_mc_fragile", + "copy_mc_fragile_handle_tail", "ftrace_likely_update", /* CONFIG_TRACE_BRANCH_PROFILING */ NULL }; diff --git a/tools/perf/bench/Build b/tools/perf/bench/Build index dd68a40a790c..878db6a59a41 100644 --- a/tools/perf/bench/Build +++ b/tools/perf/bench/Build @@ -13,7 +13,6 @@ perf-y += synthesize.o perf-y += kallsyms-parse.o perf-y += find-bit-bench.o -perf-$(CONFIG_X86_64) += mem-memcpy-x86-64-lib.o perf-$(CONFIG_X86_64) += mem-memcpy-x86-64-asm.o perf-$(CONFIG_X86_64) += mem-memset-x86-64-asm.o diff --git a/tools/perf/bench/mem-memcpy-x86-64-lib.c b/tools/perf/bench/mem-memcpy-x86-64-lib.c deleted file mode 100644 index 4130734dde84..000000000000 --- a/tools/perf/bench/mem-memcpy-x86-64-lib.c +++ /dev/null @@ -1,24 +0,0 @@ -/* - * From code in arch/x86/lib/usercopy_64.c, copied to keep tools/ copy - * of the kernel's arch/x86/lib/memcpy_64.s used in 'perf bench mem memcpy' - * happy. - */ -#include - -unsigned long __memcpy_mcsafe(void *dst, const void *src, size_t cnt); -unsigned long mcsafe_handle_tail(char *to, char *from, unsigned len); - -unsigned long mcsafe_handle_tail(char *to, char *from, unsigned len) -{ - for (; len; --len, to++, from++) { - /* - * Call the assembly routine back directly since - * memcpy_mcsafe() may silently fallback to memcpy. - */ - unsigned long rem = __memcpy_mcsafe(to, from, 1); - - if (rem) - break; - } - return len; -} diff --git a/tools/testing/nvdimm/test/nfit.c b/tools/testing/nvdimm/test/nfit.c index a1a5dc645b40..2ac0fff6dad8 100644 --- a/tools/testing/nvdimm/test/nfit.c +++ b/tools/testing/nvdimm/test/nfit.c @@ -23,7 +23,8 @@ #include "nfit_test.h" #include "../watermark.h" -#include +#include +#include /* * Generate an NFIT table to describe the following topology: @@ -3283,7 +3284,7 @@ static struct platform_driver nfit_test_driver = { .id_table = nfit_test_id, }; -static char mcsafe_buf[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE))); +static char copy_mc_buf[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE))); enum INJECT { INJECT_NONE, @@ -3291,7 +3292,7 @@ enum INJECT { INJECT_DST, }; -static void mcsafe_test_init(char *dst, char *src, size_t size) +static void copy_mc_test_init(char *dst, char *src, size_t size) { size_t i; @@ -3300,7 +3301,7 @@ static void mcsafe_test_init(char *dst, char *src, size_t size) src[i] = (char) i; } -static bool mcsafe_test_validate(unsigned char *dst, unsigned char *src, +static bool copy_mc_test_validate(unsigned char *dst, unsigned char *src, size_t size, unsigned long rem) { size_t i; @@ -3321,12 +3322,12 @@ static bool mcsafe_test_validate(unsigned char *dst, unsigned char *src, return true; } -void mcsafe_test(void) +void copy_mc_test(void) { char *inject_desc[] = { "none", "source", "destination" }; enum INJECT inj; - if (IS_ENABLED(CONFIG_MCSAFE_TEST)) { + if (IS_ENABLED(CONFIG_COPY_MC_TEST)) { pr_info("%s: run...\n", __func__); } else { pr_info("%s: disabled, skip.\n", __func__); @@ -3344,31 +3345,31 @@ void mcsafe_test(void) switch (inj) { case INJECT_NONE: - mcsafe_inject_src(NULL); - mcsafe_inject_dst(NULL); - dst = &mcsafe_buf[2048]; - src = &mcsafe_buf[1024 - i]; + copy_mc_inject_src(NULL); + copy_mc_inject_dst(NULL); + dst = ©_mc_buf[2048]; + src = ©_mc_buf[1024 - i]; expect = 0; break; case INJECT_SRC: - mcsafe_inject_src(&mcsafe_buf[1024]); - mcsafe_inject_dst(NULL); - dst = &mcsafe_buf[2048]; - src = &mcsafe_buf[1024 - i]; + copy_mc_inject_src(©_mc_buf[1024]); + copy_mc_inject_dst(NULL); + dst = ©_mc_buf[2048]; + src = ©_mc_buf[1024 - i]; expect = 512 - i; break; case INJECT_DST: - mcsafe_inject_src(NULL); - mcsafe_inject_dst(&mcsafe_buf[2048]); - dst = &mcsafe_buf[2048 - i]; - src = &mcsafe_buf[1024]; + copy_mc_inject_src(NULL); + copy_mc_inject_dst(©_mc_buf[2048]); + dst = ©_mc_buf[2048 - i]; + src = ©_mc_buf[1024]; expect = 512 - i; break; } - mcsafe_test_init(dst, src, 512); - rem = __memcpy_mcsafe(dst, src, 512); - valid = mcsafe_test_validate(dst, src, 512, expect); + copy_mc_test_init(dst, src, 512); + rem = copy_mc_fragile(dst, src, 512); + valid = copy_mc_test_validate(dst, src, 512, expect); if (rem == expect && valid) continue; pr_info("%s: copy(%#lx, %#lx, %d) off: %d rem: %ld %s expect: %ld\n", @@ -3380,8 +3381,8 @@ void mcsafe_test(void) } } - mcsafe_inject_src(NULL); - mcsafe_inject_dst(NULL); + copy_mc_inject_src(NULL); + copy_mc_inject_dst(NULL); } static __init int nfit_test_init(void) @@ -3392,7 +3393,7 @@ static __init int nfit_test_init(void) libnvdimm_test(); acpi_nfit_test(); device_dax_test(); - mcsafe_test(); + copy_mc_test(); dax_pmem_test(); dax_pmem_core_test(); #ifdef CONFIG_DEV_DAX_PMEM_COMPAT diff --git a/tools/testing/selftests/powerpc/copyloops/.gitignore b/tools/testing/selftests/powerpc/copyloops/.gitignore index ddaf140b8255..994b11af765c 100644 --- a/tools/testing/selftests/powerpc/copyloops/.gitignore +++ b/tools/testing/selftests/powerpc/copyloops/.gitignore @@ -12,4 +12,4 @@ memcpy_p7_t1 copyuser_64_exc_t0 copyuser_64_exc_t1 copyuser_64_exc_t2 -memcpy_mcsafe_64 +copy_mc_64 diff --git a/tools/testing/selftests/powerpc/copyloops/Makefile b/tools/testing/selftests/powerpc/copyloops/Makefile index 0917983a1c78..3095b1f1c02b 100644 --- a/tools/testing/selftests/powerpc/copyloops/Makefile +++ b/tools/testing/selftests/powerpc/copyloops/Makefile @@ -12,7 +12,7 @@ ASFLAGS = $(CFLAGS) -Wa,-mpower4 TEST_GEN_PROGS := copyuser_64_t0 copyuser_64_t1 copyuser_64_t2 \ copyuser_p7_t0 copyuser_p7_t1 \ memcpy_64_t0 memcpy_64_t1 memcpy_64_t2 \ - memcpy_p7_t0 memcpy_p7_t1 memcpy_mcsafe_64 \ + memcpy_p7_t0 memcpy_p7_t1 copy_mc_64 \ copyuser_64_exc_t0 copyuser_64_exc_t1 copyuser_64_exc_t2 EXTRA_SOURCES := validate.c ../harness.c stubs.S @@ -45,9 +45,9 @@ $(OUTPUT)/memcpy_p7_t%: memcpy_power7.S $(EXTRA_SOURCES) -D SELFTEST_CASE=$(subst memcpy_p7_t,,$(notdir $@)) \ -o $@ $^ -$(OUTPUT)/memcpy_mcsafe_64: memcpy_mcsafe_64.S $(EXTRA_SOURCES) +$(OUTPUT)/copy_mc_64: copy_mc_64.S $(EXTRA_SOURCES) $(CC) $(CPPFLAGS) $(CFLAGS) \ - -D COPY_LOOP=test_memcpy_mcsafe \ + -D COPY_LOOP=test_copy_mc_generic \ -o $@ $^ $(OUTPUT)/copyuser_64_exc_t%: copyuser_64.S exc_validate.c ../harness.c \ diff --git a/tools/testing/selftests/powerpc/copyloops/copy_mc_64.S b/tools/testing/selftests/powerpc/copyloops/copy_mc_64.S new file mode 120000 index 000000000000..dcbe06d500fb --- /dev/null +++ b/tools/testing/selftests/powerpc/copyloops/copy_mc_64.S @@ -0,0 +1 @@ +../../../../../arch/powerpc/lib/copy_mc_64.S \ No newline at end of file diff --git a/tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S b/tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S deleted file mode 120000 index f0feef3062f6..000000000000 --- a/tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S +++ /dev/null @@ -1 +0,0 @@ -../../../../../arch/powerpc/lib/memcpy_mcsafe_64.S \ No newline at end of file -- cgit v1.2.3