From: Roland McGrath Date: Wed, 30 Jan 2008 12:30:52 +0000 (+0100) Subject: x86: x86-32 ptrace debugreg cleanup X-Git-Tag: v2.6.25-rc1~1143^2~693 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d9771e8c50020bb1b4ca9eca9c188874ff126aa4;p=linux-2.6 x86: x86-32 ptrace debugreg cleanup This cleans up the 32-bit ptrace code to separate the guts of the debug register access from the implementation of PTRACE_PEEKUSR and PTRACE_POKEUSR. The new functions ptrace_[gs]et_debugreg match the new 64-bit entry points for parity, but they don't need to be global. Signed-off-by: Roland McGrath Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/kernel/ptrace_32.c b/arch/x86/kernel/ptrace_32.c index a1425e9ad0..512f8412b7 100644 --- a/arch/x86/kernel/ptrace_32.c +++ b/arch/x86/kernel/ptrace_32.c @@ -118,6 +118,72 @@ static unsigned long getreg(struct task_struct *child, unsigned long regno) return retval; } +/* + * This function is trivial and will be inlined by the compiler. + * Having it separates the implementation details of debug + * registers from the interface details of ptrace. + */ +static unsigned long ptrace_get_debugreg(struct task_struct *child, int n) +{ + return child->thread.debugreg[n]; +} + +static int ptrace_set_debugreg(struct task_struct *child, + int n, unsigned long data) +{ + if (unlikely(n == 4 || n == 5)) + return -EIO; + + if (n < 4 && unlikely(data >= TASK_SIZE - 3)) + return -EIO; + + if (n == 7) { + /* + * Sanity-check data. Take one half-byte at once with + * check = (val >> (16 + 4*i)) & 0xf. It contains the + * R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits + * 2 and 3 are LENi. Given a list of invalid values, + * we do mask |= 1 << invalid_value, so that + * (mask >> check) & 1 is a correct test for invalid + * values. + * + * R/Wi contains the type of the breakpoint / + * watchpoint, LENi contains the length of the watched + * data in the watchpoint case. + * + * The invalid values are: + * - LENi == 0x10 (undefined), so mask |= 0x0f00. + * - R/Wi == 0x10 (break on I/O reads or writes), so + * mask |= 0x4444. + * - R/Wi == 0x00 && LENi != 0x00, so we have mask |= + * 0x1110. + * + * Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54. + * + * See the Intel Manual "System Programming Guide", + * 15.2.4 + * + * Note that LENi == 0x10 is defined on x86_64 in long + * mode (i.e. even for 32-bit userspace software, but + * 64-bit kernel), so the x86_64 mask value is 0x5454. + * See the AMD manual no. 24593 (AMD64 System Programming) + */ + int i; + data &= ~DR_CONTROL_RESERVED; + for (i = 0; i < 4; i++) + if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1) + return -EIO; + if (data) + set_tsk_thread_flag(child, TIF_DEBUG); + else + clear_tsk_thread_flag(child, TIF_DEBUG); + } + + child->thread.debugreg[n] = data; + + return 0; +} + /* * Called by kernel/ptrace.c when detaching.. * @@ -158,7 +224,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data) addr <= (long) &dummy->u_debugreg[7]){ addr -= (long) &dummy->u_debugreg[0]; addr = addr >> 2; - tmp = child->thread.debugreg[addr]; + tmp = ptrace_get_debugreg(child, addr); } ret = put_user(tmp, datap); break; @@ -188,56 +254,9 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data) ret = -EIO; if(addr >= (long) &dummy->u_debugreg[0] && addr <= (long) &dummy->u_debugreg[7]){ - - if(addr == (long) &dummy->u_debugreg[4]) break; - if(addr == (long) &dummy->u_debugreg[5]) break; - if(addr < (long) &dummy->u_debugreg[4] && - ((unsigned long) data) >= TASK_SIZE-3) break; - - /* Sanity-check data. Take one half-byte at once with - * check = (val >> (16 + 4*i)) & 0xf. It contains the - * R/Wi and LENi bits; bits 0 and 1 are R/Wi, and bits - * 2 and 3 are LENi. Given a list of invalid values, - * we do mask |= 1 << invalid_value, so that - * (mask >> check) & 1 is a correct test for invalid - * values. - * - * R/Wi contains the type of the breakpoint / - * watchpoint, LENi contains the length of the watched - * data in the watchpoint case. - * - * The invalid values are: - * - LENi == 0x10 (undefined), so mask |= 0x0f00. - * - R/Wi == 0x10 (break on I/O reads or writes), so - * mask |= 0x4444. - * - R/Wi == 0x00 && LENi != 0x00, so we have mask |= - * 0x1110. - * - * Finally, mask = 0x0f00 | 0x4444 | 0x1110 == 0x5f54. - * - * See the Intel Manual "System Programming Guide", - * 15.2.4 - * - * Note that LENi == 0x10 is defined on x86_64 in long - * mode (i.e. even for 32-bit userspace software, but - * 64-bit kernel), so the x86_64 mask value is 0x5454. - * See the AMD manual no. 24593 (AMD64 System - * Programming)*/ - - if(addr == (long) &dummy->u_debugreg[7]) { - data &= ~DR_CONTROL_RESERVED; - for(i=0; i<4; i++) - if ((0x5f54 >> ((data >> (16 + 4*i)) & 0xf)) & 1) - goto out_tsk; - if (data) - set_tsk_thread_flag(child, TIF_DEBUG); - else - clear_tsk_thread_flag(child, TIF_DEBUG); - } addr -= (long) &dummy->u_debugreg; addr = addr >> 2; - child->thread.debugreg[addr] = data; - ret = 0; + ret = ptrace_set_debugreg(child, addr, data); } break; @@ -335,7 +354,7 @@ long arch_ptrace(struct task_struct *child, long request, long addr, long data) ret = ptrace_request(child, request, addr, data); break; } - out_tsk: + return ret; }