Re: [PATCH] Semihosting ctr0 typo (adr/ldr)?
Richard Earnshaw via Newlib <[email protected]>
| Newsgroups | gmane.comp.lib.newlib |
|---|---|
| Message-ID | <[email protected]> |
On 17/02/2021 10:01, Corinna Vinschen wrote: > On Feb 16 22:56, iNvEr7 via Newlib wrote: >> >> --- >> libgloss/arm/crt0.S | 2 +- >> newlib/libc/sys/arm/crt0.S | 2 +- >> 2 files changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/libgloss/arm/crt0.S b/libgloss/arm/crt0.S >> index 8490bde2f..b8bbcee18 100644 >> --- a/libgloss/arm/crt0.S >> +++ b/libgloss/arm/crt0.S >> @@ -283,7 +283,7 @@ >> #ifdef ARM_RDI_MONITOR >> /* Issue Angel SWI to read stack info. */ >> movs r0, #AngelSWI_Reason_HeapInfo >> - adr r1, .LC0 /* Point at ptr to 4 words to receive data. */ >> + ldr r1, .LC0 /* Point at ptr to 4 words to receive data. */ >> #ifdef THUMB_VXM >> bkpt AngelSWI >> #elif defined(__thumb2__) >> diff --git a/newlib/libc/sys/arm/crt0.S b/newlib/libc/sys/arm/crt0.S >> index 5e677a23c..3c5771229 100644 >> --- a/newlib/libc/sys/arm/crt0.S >> +++ b/newlib/libc/sys/arm/crt0.S >> @@ -270,7 +270,7 @@ >> #ifdef ARM_RDI_MONITOR >> /* Issue Angel SWI to read stack info. */ >> movs r0, #AngelSWI_Reason_HeapInfo >> - adr r1, .LC0 /* Point at ptr to 4 words to receive data. */ >> + ldr r1, .LC0 /* Point at ptr to 4 words to receive data. */ >> #ifdef THUMB_VXM >> bkpt AngelSWI >> #elif defined(__thumb2__) >> -- >> 2.29.2 > > I'm a bit suprised that this problem hasn't been noticed for the > last 10 years. I'm not familiar with the ARM stuff at all, so maybe > somebody from ARM can chime in here? > > > Thanks, > Corinna > No, I don't think that is right, but it took some digging to be sure. The specification for the HeapInfo syscall is here: https://developer.arm.com/documentation/100863/0300/Semihosting-operations/SYS-HEAPINFO--0x16-?lang=en and it says that the parameter is the /address of a pointer/ to the 4-word block. In other words, it is not the address of the block itself. It's odd that it is defined this way, but I think the code is doing what the specification says. Certainly the comments in the code seem to reflect this. R.