Re: [PATCH] objtool: Detect assembly code falling through to INT3 padding

2018-05-19 Thread hpa
On May 18, 2018 10:51:36 AM PDT, Alexey Dobriyan wrote: >On Fri, May 18, 2018 at 09:18:14AM +0200, Ingo Molnar wrote: >> The concept of built-in kernel tooling working at the machine code >level is just >> so powerful - we should have added our own KCC compiler 20 years ago. > >...for two very se

Re: [PATCH] objtool: Detect assembly code falling through to INT3 padding

2018-05-18 Thread Alexey Dobriyan
On Fri, May 18, 2018 at 09:18:14AM +0200, Ingo Molnar wrote: > The concept of built-in kernel tooling working at the machine code level is > just > so powerful - we should have added our own KCC compiler 20 years ago. ...for two very serious reasons * C as a language moves very slowly, last hel

Re: [PATCH] objtool: Detect assembly code falling through to INT3 padding

2018-05-18 Thread Borislav Petkov
On Fri, May 18, 2018 at 12:27:15AM -0700, H. Peter Anvin wrote: > On 05/18/18 00:18, Ingo Molnar wrote: > > > > Ok, this is cool, it addresses the robustness problem that INT3 padding > > introduced > > very nicely. > > > > The concept of built-in kernel tooling working at the machine code leve

Re: [PATCH] objtool: Detect assembly code falling through to INT3 padding

2018-05-18 Thread Ingo Molnar
* Ingo Molnar wrote: > > * Josh Poimboeuf wrote: > > > With the following commit: > > > > 51bad67ffbce ("x86/asm: Pad assembly functions with INT3 instructions") > > > > ... asm function alignments are padded with INT3, so it's no longer safe > > to fall through to an aligned function. M

Re: [PATCH] objtool: Detect assembly code falling through to INT3 padding

2018-05-18 Thread H. Peter Anvin
On 05/18/18 00:18, Ingo Molnar wrote: > > Ok, this is cool, it addresses the robustness problem that INT3 padding > introduced > very nicely. > > The concept of built-in kernel tooling working at the machine code level is > just > so powerful - we should have added our own KCC compiler 20 yea

Re: [PATCH] objtool: Detect assembly code falling through to INT3 padding

2018-05-18 Thread Ingo Molnar
* Peter Zijlstra wrote: > On Thu, May 17, 2018 at 08:49:34AM -0500, Josh Poimboeuf wrote: > > With the following commit: > > > > 51bad67ffbce ("x86/asm: Pad assembly functions with INT3 instructions") > > > > ... asm function alignments are padded with INT3, so it's no longer safe > > to fal

Re: [PATCH] objtool: Detect assembly code falling through to INT3 padding

2018-05-18 Thread Ingo Molnar
* Josh Poimboeuf wrote: > With the following commit: > > 51bad67ffbce ("x86/asm: Pad assembly functions with INT3 instructions") > > ... asm function alignments are padded with INT3, so it's no longer safe > to fall through to an aligned function. Make sure we catch any such > cases with ob

Re: [PATCH] objtool: Detect assembly code falling through to INT3 padding

2018-05-17 Thread Peter Zijlstra
On Thu, May 17, 2018 at 08:49:34AM -0500, Josh Poimboeuf wrote: > With the following commit: > > 51bad67ffbce ("x86/asm: Pad assembly functions with INT3 instructions") > > ... asm function alignments are padded with INT3, so it's no longer safe > to fall through to an aligned function. Make s

[PATCH] objtool: Detect assembly code falling through to INT3 padding

2018-05-17 Thread Josh Poimboeuf
With the following commit: 51bad67ffbce ("x86/asm: Pad assembly functions with INT3 instructions") ... asm function alignments are padded with INT3, so it's no longer safe to fall through to an aligned function. Make sure we catch any such cases with objtool. Note this only adds checking for