ruby-changes:69006
From: Maxime <ko1@a...>
Date: Thu, 21 Oct 2021 08:19:40 +0900 (JST)
Subject: [ruby-changes:69006] cf2b508375 (master): Try to alloc executable memory within rel32 range on Linux machines (#12)
https://git.ruby-lang.org/ruby.git/commit/?id=cf2b508375 From cf2b508375c0b1d3c67f108861afb454a5110790 Mon Sep 17 00:00:00 2001 From: Maxime Chevalier-Boisvert <maximechevalierb@g...> Date: Tue, 27 Apr 2021 11:37:06 -0400 Subject: Try to alloc executable memory within rel32 range on Linux machines (#12) * Use INT32_MIN, INT32_MAX, etc. constants in yjit_asm.c * Print warning on stderr when code past rel32 jump range * Fix preprocessor snafu * Move rel32 warning into --yjit-stats * Try to allocate within rel32 offset on Linux machines * Update yjit_asm.c Co-authored-by: Alan Wu <XrXr@u...> * On Linux, use sysconf to get the page size Co-authored-by: Alan Wu <XrXr@u...> --- yjit_asm.c | 101 ++++++++++++++++++++++++++++++++++++++++++++--------------- yjit_iface.c | 7 +++++ 2 files changed, 82 insertions(+), 26 deletions(-) diff --git a/yjit_asm.c b/yjit_asm.c index 658468f02c..c47e1fd274 100644 --- a/yjit_asm.c +++ b/yjit_asm.c @@ -5,10 +5,12 @@ https://github.com/ruby/ruby/blob/trunk/yjit_asm.c#L5 #include <stdlib.h> #include <string.h> #include <stdarg.h> +#include <stdint.h> #include <assert.h> +// For mmapp(), sysconf() #ifndef _WIN32 -// For mmapp() +#include <unistd.h> #include <sys/mman.h> #endif @@ -18,11 +20,11 @@ https://github.com/ruby/ruby/blob/trunk/yjit_asm.c#L20 uint32_t sig_imm_size(int64_t imm) { // Compute the smallest size this immediate fits in - if (imm >= -128 && imm <= 127) + if (imm >= INT8_MIN && imm <= INT8_MAX) return 8; - if (imm >= -32768 && imm <= 32767) + if (imm >= INT16_MIN && imm <= INT16_MAX) return 16; - if (imm >= -2147483648 && imm <= 2147483647) + if (imm >= INT32_MIN && imm <= INT32_MAX) return 32; return 64; @@ -32,11 +34,11 @@ uint32_t sig_imm_size(int64_t imm) https://github.com/ruby/ruby/blob/trunk/yjit_asm.c#L34 uint32_t unsig_imm_size(uint64_t imm) { // Compute the smallest size this immediate fits in - if (imm <= 255) + if (imm <= UINT8_MAX) return 8; - else if (imm <= 65535) + else if (imm <= UINT16_MAX) return 16; - else if (imm <= 4294967295) + else if (imm <= UINT32_MAX) return 32; return 64; @@ -124,23 +126,73 @@ x86opnd_t const_ptr_opnd(const void *ptr) https://github.com/ruby/ruby/blob/trunk/yjit_asm.c#L126 return opnd; } +// Align the current write position to a multiple of bytes +static uint8_t* align_ptr(uint8_t* ptr, uint32_t multiple) +{ + // Compute the pointer modulo the given alignment boundary + uint32_t rem = ((uint32_t)(uintptr_t)ptr) % multiple; + + // If the pointer is already aligned, stop + if (rem == 0) + return ptr; + + // Pad the pointer by the necessary amount to align it + uint32_t pad = multiple - rem; + + return ptr + pad; +} + // Allocate a block of executable memory uint8_t* alloc_exec_mem(uint32_t mem_size) { #ifndef _WIN32 - // Map the memory as executable - uint8_t* mem_block = (uint8_t*)mmap( - (void*)&alloc_exec_mem, - mem_size, - PROT_READ | PROT_WRITE | PROT_EXEC, - MAP_PRIVATE | MAP_ANONYMOUS, - -1, - 0 - ); + uint8_t* mem_block; + + // On Linux + #if defined(MAP_FIXED_NOREPLACE) && defined(_SC_PAGESIZE) + // Align the requested address to page size + uint32_t page_size = (uint32_t)sysconf(_SC_PAGESIZE); + uint8_t* req_addr = align_ptr((uint8_t*)&alloc_exec_mem, page_size); + + while (req_addr < (uint8_t*)&alloc_exec_mem + INT32_MAX) + { + // Try to map a chunk of memory as executable + mem_block = (uint8_t*)mmap( + (void*)req_addr, + mem_size, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED_NOREPLACE, + -1, + 0 + ); + // If we succeeded, stop + if (mem_block != MAP_FAILED) { + break; + } + + // +4MB + req_addr += 4 * 1024 * 1024; + } + + // On MacOS and other platforms + #else + // Try to map a chunk of memory as executable + mem_block = (uint8_t*)mmap( + (void*)alloc_exec_mem, + mem_size, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_PRIVATE | MAP_ANONYMOUS, + -1, + 0 + ); + #endif + + // Fallback if (mem_block == MAP_FAILED) { + // Try again without the address hint (e.g., valgrind) mem_block = (uint8_t*)mmap( - NULL, // try again without the address hint (e.g., valgrind) + NULL, mem_size, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS, @@ -161,6 +213,7 @@ uint8_t* alloc_exec_mem(uint32_t mem_size) https://github.com/ruby/ruby/blob/trunk/yjit_asm.c#L213 return mem_block; #else + // Windows not supported for now return NULL; #endif } @@ -180,15 +233,11 @@ void cb_align_pos(codeblock_t* cb, uint32_t multiple) https://github.com/ruby/ruby/blob/trunk/yjit_asm.c#L233 { // Compute the pointer modulo the given alignment boundary uint8_t* ptr = &cb->mem_block[cb->write_pos]; - uint32_t rem = ((uint32_t)(uintptr_t)ptr) % multiple; - - // If the pointer is already aligned, stop - if (rem == 0) - return; + uint8_t* aligned_ptr = align_ptr(ptr, multiple); // Pad the pointer by the necessary amount to align it - uint32_t pad = multiple - rem; - cb->write_pos += pad; + ptrdiff_t pad = aligned_ptr - ptr; + cb->write_pos += (int32_t)pad; } // Set the current write position @@ -818,7 +867,7 @@ void cb_write_jcc_ptr(codeblock_t* cb, const char* mnem, uint8_t op0, uint8_t op https://github.com/ruby/ruby/blob/trunk/yjit_asm.c#L867 // Compute the jump offset int64_t rel64 = (int64_t)(dst_ptr - end_ptr); - assert (rel64 >= -2147483648 && rel64 <= 2147483647); + assert (rel64 >= INT32_MIN && rel64 <= INT32_MAX); // Write the relative 32-bit jump offset cb_write_int(cb, (int32_t)rel64, 32); @@ -901,7 +950,7 @@ void call_ptr(codeblock_t* cb, x86opnd_t scratch_reg, uint8_t* dst_ptr) https://github.com/ruby/ruby/blob/trunk/yjit_asm.c#L950 int64_t rel64 = (int64_t)(dst_ptr - end_ptr); // If the offset fits in 32-bit - if (rel64 >= -2147483648 && rel64 <= 2147483647) + if (rel64 >= INT32_MIN && rel64 <= INT32_MAX) { call_rel32(cb, (int32_t)rel64); return; diff --git a/yjit_iface.c b/yjit_iface.c index afd9b774cb..a84cf0d323 100644 --- a/yjit_iface.c +++ b/yjit_iface.c @@ -896,6 +896,13 @@ print_yjit_stats(void) https://github.com/ruby/ruby/blob/trunk/yjit_iface.c#L896 return; } + // Warn if the executable code block is out of the relative + // 32-bit jump range away from compiled C code + ptrdiff_t start_diff = (cb->mem_block + cb->mem_size) - (uint8_t*)&print_yjit_stats; + if (start_diff < INT32_MIN || start_diff > INT32_MAX) { + fprintf(stderr, "WARNING: end of code block past rel32 offset range from C code\n"); + } + // Compute the total exit count int64_t total_exit_count = calc_total_exit_count(); -- cgit v1.2.1 -- ML: ruby-changes@q... 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